Generic Declarative Expression Builder in PHP - php

Folks,
I'm looking to build a piece of PHP5 UI that I'm pretty sure is common to a bunch of applications. Basically, it's an expression builder that allows users to specify expressions combined through logical operators (AND/OR), like this:
FieldX > 3 AND FieldY = 5
FieldY = "bob" and FieldZ is not null
FieldX > '5/23/2007' OR (FieldY = 5 AND FieldY is not null)
Ideally, a system like that would allow me as a programmer to specify the list of parameters that the user can pick (columns) and the data type for each. It would also provide a nice, user-friendly interface for defining expressions like that - I'm imagining something like a table, where each row has several pickers:
[Column] [Condition] [Value] [AND/OR]
[Column] [Condition] [Value] [AND/OR]
...
Do you know of an open-source component that does something like that? Or maybe a part of this kind of functionality?

A word of caution. These types of generic expression builders are commonly thought of as excellent solutions to a variety of user problems. The thinking tends to go along these lines:
The user wants all these different reports
There's no way we're giving them SQL access (even if they could understand it)
We don't have time to write all these custom reports
Therefore, I'll make an easy way for them to write queries without having to know specific syntax, tables and fields.
This is not necessarily a bad idea, but what we have found at my company is that non-techie users have surprising difficulty understanding and building expressions more complex than a group of ANDS or a group of ORS. This is hard for us programmers to grasp, as most of us probably had an intuitive understanding of boolean logic even before we learned to program.
I would recommend that you not try to give them complete flexibility to create whatever expression they want, and instead you put together a UI that lets you the programmer define something more complicated on the back-end but gives the user simple choices on the front-end. This is easier said than done, obviously.
Remember - sometimes the difficulty for end users isn't the fact that they don't know the right syntax to express their idea in. More often it's because they don't even know how to formulate their thoughts in an unambiguous way, even if they were provided an easy way to do so.
NOTE: I'm not saying the end users are always morons - just that their minds may work differently from us crazy developers.

This isn't exactly a component, but you might take a look at the Conditions tab of the Shopping Cart rule builder in Magento for a solid PHP implementation of this type of functionality. It is customized towards e-commerce, so it is not a generic database overlay, but it does have a great condition builder interface.

I think this is a very interesting idea. Are you planning on working on this project for personal use or through work?
If you are planning on working on this project personally, maybe you should write it yourself and turn it into an open source project. It looks like there is already some interest in this area and it would be a good learning experience.
Otherwise, I can see how a company could find value in something like this. It would give the programmers another utility that could help them do their job a little bit easier and pay dividends in the long run.
Either way, this project is win. You will learn alot, and create something that other people find useful.

Check this out: http://www.codeproject.com/KB/custom-controls/SqlWhereBuilder.aspx
Download the client side JavaScript Library version of the component and customize it to your needs. Cheers.

I'd start by creating an object oriented query model. Eg. Criteria-objects. The next step is then to write a UI which allows manipulation of this model structure.

I've recently done such functionality by myself and, IMHO, it's easier to write your own implementation.

I think this is more related to UI than PHP in general. You'd better retag your question. Maybe you just want to parse these definitions in PHP, in this case I'd suggest using preg_replace_callback.

why dont try using smarty which is a template engine that. you just need to get and parse the user input.
Now that I'm thinking, do this in any way will need you checking the user input to avoid injections.

Related

Could I please get some help correcting my little beginners project?

This is my first time posting something like this. I'm a complete n00b at programming/php. I was trying to grasp all the tutorials out there and wanted to create a sort of framework to base projects off of for web db/applications. I came up with a few files for crud operations that I know must really be horrible code. I was wondering if I could get some advice in advancing this 'framework' to the next level. I'm not great at OO, but I understand the concepts, so I went more functional instead. I'm aware that the songs are gross, I don't need help recognizing that.
I would like some help on the database calls. I understand I should be using PDO (to help with injection), but I'm not sure how to convert this code to that structure. I also realize that at the least I should be using mysqli functions. Again, n00b.
I am also aware of validating and sanitizing data, but again, being so new to this, I don't know where to begin. Especially if I wish to keep it tight and small. The comments are funny from a programmers aspect, but hey, you work with what you got. I'm trying to grasp MVC and be able to tie in AJAX and templates/skins, but the crux of it is to work with databases.
I do like how there is one config file that works with all the other files, and how that results in small files for index, read and delete. The others get a little longer. Not that including files is makes me cool or anything.
I think I fail horribly at understanding MVC and structuring the project so that maintaining it and adapting it is easier. I also realize that there is a lot of html in those php files which is a no-no too. How do I fill in the gaps from what I do know (I know what every line of every file is doing) to what I should know.
The code can be found here (probably not sourceforge worthy, but I want to help others learn as I do).
https://sourceforge.net/projects/eleete/files/
Building such a thing takes a good amount of time, before you go doing so I would suggest looking into open source CMSs such as Wordpress to see if they would suit you better than putting in hours of work creating something yourself, the reason I say this is because to begin with you may think it won't be too hard to create one for yourself, but as you get into it you will realize there are many avenues that need to be explored in terms of security and features.
However, if you still want to build something the most important thing is to be creating reusable, and easily understandable code. For example if you want to create db entries for things like pages, you'll want to create functions to do so, to which you can pass variables such as titles etc. A good way to begin is to create functions for collecting data from your db, for example siteinfo() could be a function that returns an array full of site info. To make sure every file has access to such functions you will need a global file like functions.php for example which you will need to include in each of your other files.
Remember, building a framework is hard work, but if you do it properly and thouraghly you should increase your productivity a good amount - this is something you need to consider when building it, make sure you're not doing things in a roundabout way. Make it simple, make it reusable, and make it powerful.
First off, welcome to the community! I hope you find here people who are excited to bring your more into the programming fold. It's an exciting place to be.
I get the impression you're biting off quite a bit. I fear you're also under the assumption you can write the perfect program from the get-go, which is a flat-out myth no matter how long you've been in the industry.
As to the former observation, my recommendation would be to pick a simple problem and try to solve it. My favorite recommendation here are simple card games - blackjack, for instance. Dice games like craps also make for short, achievable, and interesting programs. The intent of these projects will be not to build a code framework as much as your skills in dissecting problems and turning them into a solution the computer can understand and solve for you- your code.
Starting small will keep you from getting overwhelmed early. Starting fun will keep you motivated through the inevitable snags that will tempt you to throw your computer out of a closed window.
All that said, we're still here to help! Specific questions to specific problems tend to get the best feedback here, as well as questions that demonstrate you've done at least some homework on your own in terms of trying to solve it. The Stack Overflow community will be happy to give you a hand up, but not a handout. Good luck!
You're going to be much better off using a clean, simple framework. As you're so new with this stuff, I'd recommend CodeIgniter for sheer simplicity and speed. It helps enforce the MVC framework you're not totally familiar with yet, has all the built-ins you're likely looking for, and has a decent community. Being a Zend guy, I should probably suggest that, but it's definitely not the easiest to get started with.
MVC and OO are concepts you really should learn well out of the gate before going forward. This tutorial rocks. There are dozens of MVC primers out there, but in essence it boils down to separating your data layer, view layer, and the like.
PDO is not necessary to be safe, you just need to escape your sql with Mysql_escape_string or the like. I'm actually not a fan of PDO due to the monkey wrenches it throws into debugging.
Since you're new, I'd also recommend Xdebug on your server for troubleshooting. It cuts down debug time immensely.
In my experience, unless you've had to fix the shortfalls in someone else's attempt at a framework, you won't really understand how to build one yourself.
One of the key qualities of any sort of API or framework is the concept of abstraction. In a nutshell, as you find yourself repeating code, look for where the repetition could be abstracted away. The trick about this when you're building a framework is to do it in an extensible, usable fashion so that you have pieces that build on each other. In other words, abstractions can hide other abstractions. For example, It's all very well to abstract away the job of assembling an SQL UPDATE statement from a list of fields, but why does the application page have to check the list of fields is correct? Put that behind another layer that can be taught what the valid fields are for a certain object.
Another key quality that comes up at this point is refactoring. The phrase "be prepared to throw the first one away" is sometimes bandied about in programming circles. What it really means is that you should always be open to the idea of re-writing code because you've thought of a better way to do it. Even if you have to rebuild the code that calls it.

How do I design a simple web application?

I have basic knowledge of PHP and had done a few small personal projects before. Since my programs were small and usually consisted of less than five classes, I jumped into coding right away -- thinking of my database tables and user interface design as I went along. The problem was that I often found myself lost in my own ideas at the middle of my project. Hence, I thought that some form of formal planning would be practical to begin with.
I have been reading several software engineering books lately. One book said that, in web engineering, agile processes such as extreme programming and scrum should be used. I was introduced to tools such as use cases, CRC cards, and UML -- all I believe are too complicated and impractical for the simple projects I have in mind.
On the other hand, a web article I read simply suggested a rough sketch of the UI, a sitemap, and a simple workflow diagram. They seemed practical but too rudimentary and informal.
What would be a practical but formal approach to building a simple web application?
Don't be so quick to discard use cases, or some similar concept, e.g. 'user stories'. The benefit these tools bring is to make you think about what the site needs to do. That can guide all the further technical work, and help you focus on what's important instead of getting lost in interesting but low-value work.
Think about the top n things the site needs to do, and for each of these list out:
the ultimate goal for the user in this particular case
the kinds of people and other systems involved (actors, in use-case terminology)
what needs to be in place before starting this activity (the preconditions)
the basic steps the primary actor needs to perform to successfully achieve the goal
what should happen if one of those steps can't be completed
what the system looks like if the case is successfully completed (the postconditions)
what the system should look like if there were errors along the way
With a handful of these use cases, you can get an overall feel for what needs to be built to fulfill the goals. If it starts to look like too much work, you can look at which goals are of greater or lesser importance, and cut or defer those that provide less value. And if you think of new things the site should do, the existing use cases either:
provide a home for that feature, so modify the appropriate use case to incorporate the feature,
don't provide a home, indicating you missed a use case or discovered a new one, so you should elaborate on it as described above, or
don't provide a home, and therefore indicate the isn't necessary and so you shouldn't spend time on it.
The trick is to pick the proper level of abstraction and formality. Work at a high level, write informally, and you can knock these out quickly. When they're no longer useful (you have most of the application sketched out and are now heads-down working on details), put them aside. When you think of new things, see if they fit. Lather, rinse, repeat.
You have to ask yourself a few simple questions first:
1) Do I want to re-use and extend this code later?
If so, it may be a good idea to use some basic pattern such as MVC (Model-View-Controller) or use one of the many PHP frameworks available. The already established frameworks are more format in their design and how you use it. You could always use them as a basis to design your own as well.
2) Is the site you are making going to grow or change frequently? If the site isn't going to change much you could probably make something very simple and not worry too much about good design principles.
3) Do you want to learn and apply some of the techniques you mentioned? If so, then go to town and try the different techniques and see which ones appeal to you.
These kinds of questions will help you decide how you want to decide you build your website.
Start small, mock up a few simple screens, their database structure, etc. Use whatever method works for you - if that is UML diagrams, then fine. Get something finished, evaluate, and iterate from there.
This may not be quite what you are looking for, but also do yourself a favor and choose a framework such as CodeIgniter to make your life easier writing your server-side code. And similarly, consider using a client-side framework such as jQuery. This will make it easier for you when you are ready to actually sit down and write the code.
The Bare Essentials
I find there is a (roughly) four-step process that make application development a lot easier, and helps me avoid getting lost along the way. I make no pretense about using agile development methods. This is just the way I work.
Decide what the application needs to do. By "need", I mean, absolutely must do and nothing else. If it's a "nice to have" feature, write it down and come back to it later.
Figure out what data you need to keep track of to make everything work. Slugs, titles, datetimes, etc. Design the database. (I use MySQL Workbench for this.)
With your feature shortlist, prototype a user-interface with Balsamiq. Remember to add only the features you need right now.
You might consider doing HTML / CSS templates in this step.
Now that you have the data model and the UI, connect them. Business logic should focus on two things:
Abstract away from the data model so you can easily retrieve and store information from step 2.
Make the UI work exactly as you designed in step 3. Don't get fancy.
Focus on Small Goals
There are two keys to the process. The first is to to separate the design of various components. You don't want to be thinking about implementation details when designing the UI, etc. The second key is to iterate. Focus on exactly what you need to add right now and ignore everything else.
Once you're done, you can iterate and tweak, repeat steps 1-4, etc. But don't get stuck in any step for too long. You can always iterate again later if things don't turn out exactly as you like. (I think agile calls the iteration "sprints", but I'm not up on the theory.)
Practical Considerations
It helps if you have a light framework (at minimum) to assist with 4.1 (ORM, like Propel) and 4.2 (JQuery, etc.). You want to keep both the UI and data access as modular and compartmentalized as possible so it's easy to change later.
If you mix everything into one chunk of code, then you'll have to change every part of the program just to (for instance) add a new column to the database or add a new button to your app. You've had some experience, so you should have an idea of pitfalls to avoid.

Building cms for my bachelor degree and need some advice

I'm currently starting to write my own CMS in php from ground up using CakePHP (or should i use something else?) for my bachelors degree. And i'm thinking about various stuff that will be needed to do.
One of the things i can not figure out is if i should use a single file (for example, index.php will handle everything, and will include everything) or i should break up my cms into a few smaller files.
so my main questions are
is cakePHP a good choice?
use one file for everything or use multiple files?
do you have any good general advice on building more complex websites using php or any best-practices advice (i don't really understand why they don't teach us this in school)
Using a single entry point or multiple entry points becomes a moot point if you are using most frameworks. CakePHP for instance has an index.php file and all you end up doing is defining models, views, and controllers for different parts of your project. I would imagine that most frameworks these days work this way.
Alternatively, if you choose to roll your own framework and system for managing this, which given this is for a bachelor's degree may be (1) a lot of extra work but (2) more revealing and more instructive, I can speak from experience that I found having a single entry point to be useful.
It enables you to have a common code path for set-up stuff: things like enabling E_STRICT, E_NOTICE, etc. for debugging and reliability purposes. Things like sanitizing form inputs to work around the magic-quotes setting. Yes you can do that from an include 'globals.php' but:
Putting everything in one place also lets you come up with a standard file-naming convention and an __autoload handler that will help remove any include or require directives except for perhaps one. Means you can add classes and such without having to also remember to update a master file.
And this is entirely subjective, but I have found that it's easier to create simpler URLs using this. Instead of /volunteers/communities.php?id=Hedrick_Summit I can do /volunteers/communities/Hedrick_Summit which is more pleasing to me.
As for the choice of CakePHP, I have briefly toyed around with that framework. What I don't like about frameworks in general is they often have to be too general, to the point it results in extra cruft and slower page rendering. And the moment you have to do something that pushes the boundaries of the framework, and you will, you end up fighting the framework.
But to be fair, CakePHP seems to be adequate and generally well-designed. I personally took issue with the ORM layer but that was me striving for perfection and actually trying to do work in the SQL query. It has a reputation for being slow, but unless you're trying to build the next Facebook you should be fine.
Using a single file "entry point" gives you more flexibility when it comes to routing requests to various logic - you'll only ever have to worry about filtering one spot in a request chain.
These are really subjective questions.
I, once, wrote a CMS in php from ground up for my 3rd year project.
What I did was basically:
Checking how other people did it (Plume CMS and CMSmadesimple were a good start)
I didn't use any framework (that was a requirement)
and Yes, I used index.php with multiple params to handle different pages.
Answer is yes use multiple files in multiple directories, it makes all difference in the world when you need to debug or scale.
I would advise you to keep in mind the MVC (Model-View-Controller) pattern.
It is one of the most commonly used (and often misused) patterns in the CMS field.
Also, don't be afraid about looking what other people are doing. Read the code from Joomla, Drupal and other open source CMS. Have a look to language different from PHP to have a comprehensive glance about the possibilities.
Don't try to simply re-invent the wheel. Even if this is simply a Uni assignment, try to put something new on your CMS. Something that would push me to use yours instead of other CMS.
is cakePHP a good choice?
That's a highly subjective question and as such unanswerable. Though, if you want to experiment with architecture (eg. compare front controllers to page controllers), you probably should build more from scratch, as a lot of those decisions have already been made by the writers of said framework (And a lot of other frameworks, for the matter).
use one file for everything or use multiple files?
It's called a front controller (single entrypoint) or page controllers (multiple entry points). Get a copy of Patterns of Enterprise Application Architecture by M. Fowler.
do you have any good general advice on building more complex websites using php or any best-practices advice (i don't really understand why they don't teach us this in school)
There are billions of CMS's. Find some of them and analyse them to find out what they did and how they differ from each other. Trying to categorise the different approaches and compare their strenghts/weaknesses could make for a good paper.

Fully Object Oriented framework in PHP

I want to create a 100% object oriented framework in PHP with no procedural programming at all, and where everything is an object. Much like Java except it will be done in PHP.
Any pointers at what features this thing should have, should it use any of the existing design patterns such as MVC? How creating objects for every table in the database would be possible, and how displaying of HTML templates etc would be done?
Please don't link to an existing framework because I want to do this on my own mainly as a learning excercise. You will be downvoted for linking to an existing framework as your answer and saying 'this does what you want'.
Some features I'd like to have are:
Very easy CRUD page generation
AJAX based pagination
Ajax based form validation if possible, or very easy form validation
Sortable tables
Ability to edit HTML templates using PHP
I've gone through many of problems on your list, so let me spec out how I handle it. I am also OOP addict and find object techniques extremely flexible and powerful yet elegant (if done correctly).
MVC - yes, hands down, MVC is a standard for web applications. It is well documented and understandable model. Furthermore, it does on application level what OOP does on class level, that is, it keeps things separated. Nice addition to MVC is Intercepting Filter pattern. It helps to attach filters for pre- and post-processing request and response. Common use is logging requests, benchmarking, access checking, caching, etc.
OOP representation of database tables/rows is also possible. I use DAO or ActiveRecord on daily basis. Another approach to ORM issues is Row Data Gateway and Table Data Gateway. Here's example implementation of TDG utilising ArrayAccess interface.
HTML templates also can be represented as objects. I use View objects in conjunction with Smarty template engine. I find this technique EXTREMELY flexible, quick, and easy to use. Object representing view should implement __set method so every property gets propagated into Smarty template. Additionally __toString method should be implemented to support views nesting. See example:
$s = new View();
$s->template = 'view/status-bar.tpl';
$s->username = "John Doe";
$page = new View();
$page->template = 'view/page.tpl';
$page->statusBar = $s;
echo $page;
Contents of view/status-bar.tpl:
<div id="status-bar"> Hello {$username} </div>
Contents of view/page.tpl:
<html>
<head>....</head>
<body>
<ul id="main-menu">.....</ul>
{$statusBar}
... rest of the page ...
</body>
</html>
This way you only need to echo $page and inner view (status bar) will be automatically transformed into HTML. Look at complete implementation here. By the way, using one of Intercepting Filters you can wrap the returned view with HTML footer and header, so you don't have to worry about returning complete page from your controller.
The question of whether to use Ajax or not should not be important at time of design. The framework should be flexible enough to support Ajax natively.
Form validation is definitely the thing that could be done in OO manner. Build complex validator object using Composite pattern. Composite validator should iterate through form fields and assigned simple validators and give you Yes/No answer. It also should return error messages so you can update the form (via Ajax or page reload).
Another handy element is automatic translation class for changing data in db to be suitable for user interface. For example, if you have INT(1) field in db representing boolean state and use checkbox in HTML that results in empty string or "on" in _POST or _GET array you cannot just assign one into another. Having translation service that alters the data to be suitable for View or for db is a clean way of sanitizing data. Also, complexity of translation class does not litter your controller code even during very complex transformations (like the one converting Wiki syntax into HTML).
Also i18n problems can be solved using object oriented techniques. I like using __ function (double underscore) to get localised messages. The function instead of performing a lookup and returning message gives me a Proxy object and pre-registers message for later lookup. Once Proxy object is pushed into View AND View is being converted into HTML, i18n backend does look up for all pre-registered messages. This way only one query is run that returns all requested messages.
Access controll issues can be addressed using Business Delegate pattern. I described it in my other Stackoverflow answer.
Finally, if you would like to play with existing code that is fully object oriented, take look at Tigermouse framework. There are some UML diagrams on the page that may help you understand how things work. Please feel free to take over further development of this project, as I have no more time to work on it.
Have a nice hacking!
Now at the risk of being downvoted, whilst at the same time being someone who is developing their own framework, I feel compelled to tell you to at least get some experience using existing frameworks. It doesn't have to be a vast amount of experience maybe do some beginner tutorials for each of the popular ones.
Considering the amount of time it takes to build a good framework, taking the time to look into what you like and loathe about existing solutions will pale in comparison. You don't even need to just look at php frameworks. Rails, Django etc are all popular for a reason.
Building a framework is rewarding, but you need a clear plan and understanding of the task at hand, which is where research comes in.
Some answers to your questions:
Yes, it should probably use MVC as the model view controller paradigm translates well into the world of web applications.
For creating models from records in tables in your database, look into ORM's and the Active Record pattern. Existing implementations to research that I know of include Doctrine, more can be found by searching on here.
For anything AJAX related I suggest using jQuery as a starting point as it makes AJAX very easy to get up and running.
Creating your own framework is a good way to gain an appreciation for some of the things that might be going on under the hood of other frameworks. If you're a perfectionist like me, it gives you a good excuse to agonize over every little detail (e.g. is should that object be called X or Y, should I use a static method or an instance method for this).
I wrote my own (almost completely OO framework a while ago), so here's my advice:
If you've worked with other frameworks before, consider what you liked/didn't like and make sure yours gives you exactly what you want.
I personally love the MVC pattern, I wouldn't dream of doing a project without it. If you like MVC, do it, if you don't don't bother.
If you want to do JavaScript/AJAX stuff, do use a JavaScript library. Coding all your own JavaScript from scratch teaches you a bit about the DOM and JavaScript in general, but ultimately its a waste of time, focus on making your app/framework better instead.
If you don't want to adopt another framework wholesale, take a look at whether there are other open source components you like and might want to use, such as Propel, Smarty, ADOdb, or PEAR components. Writing your own framework doesn't necessarily mean writing everything from scratch.
Use design patterns where they make sense (e.g. singletons for database access perhaps), but don't obsess over them. Ultimately do whatever you think produces the neatest code.
Lastly, I learned a lot by delving into a bit of Ruby on Rails philosophy, You may never use RoR (I didn't), but some of the concepts (especially Convention over Configuration) really resonated with me and really influenced my thinking.
Ultimately, unless your needs are special most people will be more productive if they adopt an existing framework. But reinventing the wheel does teach you more about wheels.
At the risk of sounding glib, this seems to me like any other software project, in this sense:
You need to define your requirements clearly, including motivation and priorities:
WHY do this? What are the key benefits you hope to realize? If the answer is "speed" you might do one thing, if it's "ease of coding" you might do another, if it's "learning experience" you might do a thid
what are the main problems you're trying to solve? And which are most important? Security? Easy UI generation? Scalability?
The answer to "what features it should have" really depends on answers to questions like those above.
Here are my suggestions:
Stop what you're doing.
It's already been done to death.
Click this Zend Framework or that CakePHP or maybe even this Recess Framework.
Now, my reasons:
... if you've worked with developers at all, you've worked with developers that love reinventing the wheel for no good reason. This is a very, very common failure pattern.
... they would go off and write hundreds and thousands of the crappiest languages you could possibly imagine ...
... "Oh, I'm gonna create my own framework, create my own everything," and it's all gonna be crappier than stuff you could just go out and get ...
from StackOverflow Podcast # 3.
So, save yourself some time, and work on something that solves a problem for people like a web app that lets people automatically update Twitter when their cat's litter box needs cleaning. The problem of "Object Oriented PHP Framework" is done. Whatever framework you slap together will never be as reliable or useful or feature rich as any of the freely available, fully supported frameworks available TODAY.
This doesn't mean you can't have a learning experience, but why do it in the dark, creating a framework that will grow into a useless blob of code, leaving you without anything to show for your time? Develop a web app, something for people to use and enjoy, I think you'll find the experience incredibly rewarding and EDUCATIONAL.
Like Jim OHalloran said, writing your own framework gives you a very good insight into how other frameworks do things.
That said, I've written a data-access layer before that almost completely abstracted away any SQL. Application code could request the relevant object and the abstraction layer did lots of magic to fetch the data only when it was needed, didn't needlessly re-fetch, saved only when it was changed, and supported putting some objects on different databases. It also supported replicated databases, and respected replication lag, and had an intelligent collection object. It was also highly extensible: the core was parameter driven and I could add a whole new object with about 15 lines of code - and got all the magic for free.
I've also written a CRUD layout engine which was used for a considerable percentage of a site. The core was parameter driven so it could run list and edit pages for anything, once you wrote a parameter list. It automatically did pagination, save-new-delete support etc etc, leveraging the object layer above. It wasn't object-oriented in and of itself, but it could have been made so.
In other words, a object-oriented framework in PHP is not only possible, it can be very efficient. This was all in PHP 4, BTW, and I bumped up against what was possible with PHP 4 objects a couple of times. :-)
I never got as far as a central dispatch that called objects, but I wasn't far away. I've worked with several frameworks that do that, though, and the file layout can get hairy quickly. For that reason, I would go for a dispatch system that is only as complex as it needs to be and no more. A simple action/view (which is almost MVC anyway) should get you more than far enough.
I initially started creating my own framework with similar ideals to your own. However, after a couple of months I realised I was re-creating work that had been done many times over. In the end I found an open source framework which was easily extendable and used it as a basis for my own development.
The features I implemented myself:
MVC Architecture
Authentication object
Database access class
URL rewriting config
Pagination class
Email class
Encryption
The features I looked at and thought, forget it! I'll build on top of someone elses:
Caching class
Form validation class
FTP class
Plugin-ability classes
Of course, writing a framework that outperforms the open source options is possible, but why would you bother?
It's true that some developers reinvent the wheel for no good reason. But because there are already good frameworks around doesn't mean that it's a waste of time doing one yourself. I started on one a while ago with no intention of using it for anything more than an exercise. I highly recommend doing it.
I've got the perfect link for you my friend: http://nettuts.com/tutorials/php/creating-a-php5-framework-part-1/. This is an awesome tutorial I have looked at, and its not too overwhelming. Plus look around the PHP section of that site I saw an article on CRUD. As for the AJAX look elsewhere, but you have to start somewhere, and this tutorial is awesome.
Note: this tutorial has 3 parts and I think it brings up MVC in the second instalment, but starts the first part using other methods.
The one, huge selling point I would look for in a new framework is that it would make writing testable code easy.
We typically work with Zend Framework, and it's mostly awesome, but trying to unit test/test drive ZF-based code is not far short of masochism.
If you could provide a framework that replaces the MVC parts of ZF with something that allows us to write testable code, whilst still allowing us to use the library parts of ZF, I will - quite literally - buy you a beer.
I'll buy you two beers if you ditch the AJAX. There's a huge gulf between an OO PHP framework and a JavaScript framework.
Please don't link to an existing framework
I will not, I started writing my own for learning purposes, and took a peek into some of the mainstream frameworks, and even with my limited knowledge see so many mistakes and bad ideas in them.
They're built by hardcore developers, not end users.
I'm in no way saying I could write better than the "big boys" but I (along with most of you I imagine) could point out why some things they do are bad, even if just because they're not end user/non-developer friendly...
I wonder how your framework is doing, some 6 years on?
Are you still working on it? Did you stop?
Should You Write Your Own Framework
This is probably a little late for you, but for anyone else, writing your own framework is a fantastic thing to do for learning purposes.
If, however, you are wanting to write one other than learning purposes, because you cannot work out the one you are using, or because it's too bloated, then do not!
Believe me, and don't be insulted, you would not be here contemplating it if you are a knowledgeable enough developer to do so successfully!
Last year I wanted to learn OOP/classes, and more advanced PHP.
And writing my own framework was the best thing I did (am actually still doing), as I have learned so much more than I anticipated.
Along the way I've learned (to name a few):
OOP/Classes many best practices which come with it - such as
Dependency Injection, SRP
Design patterns, which help you write code and structure your system
in such a way that it makes many things logical and easy. For an
example see Wiki - SOLID
Namespaces
PHP Error Handling and all of the functionality which that provides
A more robust (and better) understanding of MVC, and how to apply it
appropriately (as there is no clear cut way to use it, just guides
and best practices).
Autoloading (of classes for OOP)
Better code writing style and more structured layout, and better
commenting skills
Naming conventions (it's fun making your own, even if based on
common practices).
And many other basic PHP things which you invariably come across accidentally from reading something.
All of this not only vastly improved my grasp of PHP and things which come with it, to a more advanced level, but also some of the commercially/widely used methods and principles.
And this all boosted my confidence in using PHP in general, which in turns makes it easier to learn.
Why Write a Framework To Learn All of This
When you start out, you learn the basics - A (variables), then B (how to write a basic function), etc.
But it doesn't take long when you're trying to learn more advanced things, that to learn and use D and E, you also have to learn and understand F, G, H, and J, and to know those you have to know K, L, and M, and to know parts of L and M you first need to understand N and O...
It becomes a minefield as trying to learn one thing brings the need to first learn a few other things, and those other things often bring a need to understand various other things.
And you end up a mile away from where you started, your mind tingling and shooting sparks from it, and about 20 tabs open all with various advanced PHP things, none of which you are 100% comfortable with.
But over time, with practice and most certainly dedication, it will all fit into place, and you'll look back at code, even a collection of files/classes, and think "Did I write that.."?
Writing a framework helped greatly with this "minefield" because:
I had specific tasks to do, which brought about the need to learn and
implement other things, but specific things. This allowed me to focus
on less things at once, and even when something branches off to
various other things, you can reel it back in to where you started
because you are working on something specific. You can do this with
any learning, but if you do not have some goal, or specific task you
are focusing on, you can easily get distracted and lost in the ether
of things to learn.
I had something practical to work with. Often reading tutorials about
an animal class, and how cat and dog classes extend animal etc,
can be confusing. When you have a real life task in your own
framework, such as how do I manage XYZ, then you can learn how
classes work easier because you have trial and error and a solid
requirement which you understand, because you created the
requirement! Not just theory-like reading which means nothing
usually.
I could put it down when my mind was blown, although as it was my
framework (my Frankenstein's monster in the beginning :P) I wanted to
press on, because it was interesting, and a personal goal to learn
and sort the next stage, to resolve an issue I was stuck with, etc.
You can do it how you want. It might not be best practice, but as long as you are trying to learn best practice, over time you will improve, and likely easier than just reading tutorials, because you are in control of what and how you do something.
Wait, I Shouldn't Re-invent the Wheel Though
Well, firstly, you cannot reinvent the wheel, it is impossible, as you will just make a wheel.
When people say "Don't reinvent the wheel", they of course mean "there are already frameworks out there", and to be fair, they are written by skilled developers.
That's not to say the frameworks don't have problems or issues, but in general they are pretty solid, secure and well written.
But the statement is nonsensical in relation to writing your own framework!
Writing your own framework for learning purposes is really useful.
Even if you plan to use it commercially, or for your own website, you haven't just "re-invented the wheel", you've made something else.
Your framework won't be like the others, it won't have many features and functionality, which might be a major advantage to you!
As long as you understand about best security practices etc, because you can think you are writing a great system, which is super fast and without all the bloat other frameworks have, but in fact you have holes in places which someone could crawl into...
But a project for learning which you don't use on the internet is ideal - or use it, eventually, when you are advanced enough to know it's secure!
With all that said, you should write your own framework IF:
You are not needing it any time soon! It takes a lot of time as
there are so many aspects to consider, learn, and trial and error
leads to refactoring (a lot at first!)
You are willing to read, code, test, change, read, code, and read
some more. There is a lot of good advice on the internet for advanced
PHP, most of it mind blowing at first, like reading all the design
patterns. But they eventually make sense, and end up helping you
resolve problems you face, and how to do things within your
framework.
Willing to put the time in, and keep trying to improve, and head
towards best practice, especially with security. Speed issues shouldn't be an issue with a small framework, and besides, if you have a fairly decent system, you can usually refactor and make speed improvements. usually if you have significant speed issues it means you've chosen intensive operations, which can usually be addressed by doing it a different way.
.
Without previous experience, or an advanced knowledge of PHP, you will likely spend some time writing a framework, further reading and knowledge will show you that your approach is skewed, and so you might delete everything and start again.
Don't be disheartened by this.
I did exactly that, as I learned so much advanced patterns and ways of doing things along the way in the first month, I ended up where refactoring was no good, and a blank canvas with a whole new approach was the only option.
However, this was quite pleasing, as I saw a much better structure take form, and I could see not only a better framework foundation start to take place, but realised it was because I had a better understanding of advanced PHP.
Just do it! Just make sure you have a plan of what you want it to do before you even write some code.
Seriously, write down on paper how you are going to load error checking, are you going to have auto loading, or include files when needed? Are you going to have a centralised loading mechanism, which instantiates classes when you need them, or some other method?
Whatever you do, and whatever stage you are at, if you are heading into new territory, plan it first. You'll be glad of it when you hit a brick wall, can go back to your plans, and realise a slight deviation to your plans will resolve it.
Otherwise you just end up with a mess and no plan or way to re-deign it to resolve the current problem or requirement you face.
You are looking to build exactly same thing I've worked on for a few years and the result is Agile Toolkit.
Very easy CRUD page generation
$page->add('CRUD')->setModel('User');
AJAX based pagination
All pagination and many other things are implemented through a native support for AJAX and Object Reloading. Below code shows a themed button with random label. Button is reloaded if clicked showing new number.
$b=$page->add('Button')->setLabel(rand(1,50));
$b->js('click')->reload();
Ajax based form validation if possible, or very easy form validation
All form validations is AJAX based. Response from server is a JavaScript chain which instructs browser to either highlight and display error message or to redirect to a next page or perform any other javascript action.
Sortable tables
Table sorting and pagination has a very intuitive and simple implementation when you can really on object reloading.
Ability to edit HTML templates using PHP
This seems out of place and a wrong thing to do. Templates are better of in the VCS.

Outlook-style rule engine

I am trying to construct a rule-based system for interpreting data. However, I am having issues deciding on a way to construct the logic for storing and interpreting rules.
Currently, there is a database structure that quite complex, but will deal with all aspects of storing the rule data. The idea is that the system will be able to mimic the way that MS Outlook allows a user to add rules.
My problems are as follows:
What pattern should I be using to store these rules inside objects?
Should I use eval() or proper object orientation to execute the rules?
And example rule might be:
Dog must have collar in area park
Where each element (dog, must have, collar, in area, park) is a separate piece of logic to be interpreted.
Any general advice to the above questions is much appreciated!
I've never implemented a system like you describe in a "real world" context, but I have played with them a considerable amount as hobby projects. My preferred approach is to use some kind of logic language like Prolog to make assertions and check them. You'd have assertions for where the park is, what it means to have something, what a dog is, and then you'd make a rule pretty much exactly like your example in parentheses at the bottom of your post. I'm sorry my Prolog is too rusty to give you a useful example... I've been playing with home-grown inference languages too long.
There are Prolog interpreters available for embedding in most languages, though I'm not sure about PHP5. You could throw together something simple that does forward-chaining inference on rule data structures of your own creation in fairly short order, if you can't find a Prolog interpreter. You may be interested in these notes on automated inference.
Probably this answer is too trivial / obvious for you but I just thought on how I would solve something like that in my current existing project which is a Zend Framework application. I thought of the filter- and validatorChains ZF uses. I assume you have a finit number of possible input objects, a finit number of conditions/constraints and a finit number of actions. In that case you would first instantiate an object and run it against a chain of conditions(validators), if all the conditions are satisfied you run the object against the actionChain. Here I would probably have to implement some kind of action priority system since some actions have to be carried out before others. Like 'sending a notification' and then 'delete' the object in question. So in ZF I would build a custom validator for every condition/constraint. I don't believe the Outlook system is very intelligent meaning that I don't think the validators are very generic.
In the db there could be a table for actual rules, one for the conditions and one for actions. Then there could be two many-to-many tables linking the rule with all needed conditions and actions.

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