I'm working with a PHP MVC Framework. Works really well. I like the separation of the business layer (model) with the business logic (controller). But i just stumbled upon a problem. Here's the thing:
Suppose i navigate to the following url:
http://localhost/user/showall/
In this case the userController.php is called and within that file there is a method showallAction() which gets executed.
In the showallAction() method i simply do a request to a model which gets all the users for me. Something like this:
public function showallAction()
{
// create userModel object
$users = new userModel();
// get all users and assign the data to a variable which can be accessed in the view
$this->view->users = $users->getAllUsers();
// render views
$this->view->render();
}
So this method gets all the users, assigns the data returned from the userModel to a variable and i can easily work with the returned data in my view. Just a typical MVC thing.
Now here comes the problem.
I also need to create a native iphone variant. Ofcourse the looks will be totally different. So all i actually want to do is to request this url:
http://localhost/user/showall/
And that it just gives me the array (in json format) back. So i can use that for the mobile development.
But this obviously can't be done right now because the showallAction() method assumes that it is for web browser display. It doesn't echo JSON formatted, instead it simply assings the array of users to a variable.
So that means i have to create another method "showallMobileAction()" in order to get the data, but specifically for the mobile device. But this is not an elegant solution. I'm sure that are better ways...
Anyone any idea how can i solve this problem??
In your situation i would modify the routing mechanism.
It would be useful, if you could add extension at the end of URL, which represents the format you expect, like :
http://foo.bar/news/latest >> HTML document
http://foo.bar/news/latest.html >> HTML document
http://foo.bar/news/latest.rss >> you RSS feed
http://foo.bar/news/latest.json >> data in JSON format
It's a simple pattern to recognize. And you can later expand this to add .. dunno .. pdf output, or Atom feeds.
Additionally , two comments :
Model is not a type of objects. Instead it is a layer, containing objects responsible for business logic, and objects responsible for data storage/retrieval.
View should be a full blown object, to which you bind the domain objects (objects responsible for business logic).
You could pass parameters to your url:
/user/showall/json
and get the third URL segment with a custom function or a built-in one. For instance, with CodeIgniter: $this->uri->segment(3).
Some frameworks will pass the additional parameters to your method. Just try this with the URL I wrote above:
public function showallAction()
{
print_r(func_get_args());
}
I'm not familiar with PHP MVC but in general terms I'd use the "accepts" HTML header field to request the response in either "text/html" or "text/json", the controller would check for the accepts type and return the response accordingly.
Related
(There is a TL;DR: at the bottom)
I have a PDF produced via MVC pattern. I am working with an existing code, which was a bit of a mess, but now I am seeing a pattern emerge.
Currently, I have a Controller class, and inside I have many many separate functions, roughly one function per page. Each function does something like this:
function showPage()
{
//get some data from repository
$data1 = $this->repository->getData1();
$data2 = $this->repository->getData2();
//pass that data to the PDF API class, aka "the view"
//and the class takes care of creating PDF pages
//with the appropriate data
$this->pdfApi->showView($data, $data2);
}
The above achieves a clean separation between Repository (which only returns data), the PDF API service (which receives the data and doesn't need to care or maintain data retrieval constructs. And Controller which pretty much just asks for Data, and passes it to PDF API. And all was well until I came across this problem:
Problem
Most every page has a "footer" with a message, and a "Proposal Number" that needs to be displayed on the page. Sometimes it also has other pieces of data. Since PDF API class has no data in itself, someone has to pass that data to PDF API. I have been passing the above to pieces of information every time as part of function parameters but it became inconvenient -- there are too many parameters to pass and they are cluttering up the code.
Try at Solution
To reduce the clutter in parameter passing, In my Controller I have created pulled data (via Repository) for variables such as $footerText and $proposalNumber and then used them I populate PDF API's own class properties. Side-effect of this is that now my PDF API has the relevant bits of data embedded directly in the API (which I consider to be undesirable, since data layer now imposes into API class)
So far I have resisted the temptation to just pass the entire Repository object to PDF API because that will do very much the same - mix data layer and API Layer, plus, API layer will have unrestricted access to Data, which can also be undesirable.
Actual Problem
When I want clean layer separation, my code is cluttered with multiple function parameter passing.
When I pass the entire Repository to my API class, I mix data and API layers, and API layer gets too much freedom to use Repository class.
Can I somehow achieve layer separation without the clutter or "mixing layers" issues identified above?
If you like to see code, here is some code below of my various unsuccessful tries :)
TL;DR: My various unsuccessful tries to keep layers separate or to reduce clutter proved to be unsuccessful
//in Controller - Exhibit 1
//Separation achieved with only data parameter passing tying layers together
//but, too much clutter -- too many parameters
//maximum layer separation but lots of annoying data passing
$data1 = $this->repository->getData1();
....
$data24 = $this->repository->getData24();
$this->pdfApi->showView($data1, $data2, $data3, ... );
//in Controller - Exhibit 2
//Layers are mixed - my data is now tied into API
//in constructor
$data1 = $this->repository->getData1();
....
$data24 = $this->repository->getData24();
$this->pdfApi->setData1($data1);
$this->pdfApi->setData24($data24);
//inside function (API already has data as part of its own vars):
$this->pdfApi->showView();
//in Controller - Exhibit 3
//layers are mixed -- entire Repository got into my API
//in constructor
$repo = new Repository();
$this->pdfApi->setRepository($repo);
//inside function (API has full Repository access gets its own data and more):
$this->pdfApi->showView();
I think the Exhibit 1 is most correct.
//inside Controller
$data = array(
'data1' => $this->repository->getData1(),
//...
'data24' => $this->repository->getData4()
):
$this->pdfApi->showView($data);
I say this because a popular framework, ZF2, which I use, also ascribes to the same pattern.
//inside Controller
$data = array(
'message' => 'Hello world',
);
$view = new ViewModel($data);
In my case the View is the PDF API
Using MVC I have something like this:
class Controller
{
//returns View
function indexAction()
{
$data = $this->getData($this->id);
$view = new ViewModel();
$view->setVariable('data' => $data);
//used to render HTML template + data above later on
return $view;
}
//gets data from DB
//currently also does business-proprietary computation on data
function getData($id)
{
//repository/dao pattern
$data = $this->repository->getData($id);
//Business Logic "derivation"
foreach ($data as $datum)
{
//that does not go into "Controller
//that does not go into "Repository"
//but where does it go? - that's my question
$derivedData[] = (new Business())->doLogic($datum);
}
return $derivedData;
}
}
Recap
I used Controller to get my data out of DB using Repository pattern, then placed received data into view. But business-related computations are left stranded.
Question
Where do I place my business logic computations that act on the data gotten from repository? The derived data which is to return to Controller later, to be placed into View?
My personal choices of architecture are usually to:
Have small controllers as thin as I can, doing only session and general right checking
Services that are handling all business logic, one (one classe yes) per potential feature I need
Services are querying repositories, and eventually manipulate the data in and out, but usually no Controller, nor view will do a ->save() anywhere.
This means that those services are usually designed to be independent from the database and easier to be tested because they only take care of one and only one task.
In your example, the whole function getData will be a service that I would call GetCarDataById. This assuming that you manipulate Cars, I don't like to leave data wandering alone.
EDIT: to make it clear, this kind of approach is not MVC to some definition, most people interpret MVC as putting all code either in controller, either in repositories (model). To others view, MVC doesn't mean that you have other classes, what I call services, and actually most of my code lives here.
The MVC pattern is clear for me.
From wikipedia:
The model directly manages the data, logic and rules of the
application. A view can be any output representation of information,
such as a chart or a diagram. Multiple views of the same information
are possible, such as a bar chart for management and a tabular view
for accountants. The third part, the controller, accepts input and
converts it to commands for the model or view.
Answering your question. The modifications goes in the model domain.
I have been trying to pass an array that is generated in view to controller.
Say, $abc=array(); How do I sent this array to controller, then process it and sent this array to another view?
Is it even feasible? Not getting any answer after googling! Please help.
I see no point to generate array from inside the view.
It depends how your framework passes the data between the layers.
For example the controller do pass the data to the View object.
I.e.
public function someMethodInController() {
$this->view->varName['arr_key'] = 'something';
}
But talking about view, it might not have a certain controller already instantiated (usually it's against the MVC paradigm)
So I see two major ways:
Instantiate a controller (I would not prefer this)
$controller = MyController();
$controller->abc = $abc;
Or use sessions. This way to transmit data is universal inbetween your domain, and does not care if you are using a certain pattern, or how do you transmit between layers.
$_SESSION['abc'] = $abc;
Once assigned, you can use it in the same session from each of your files.
Alright so I'm trying to make some sense of all these patterns.
Alright, so I'm coding an applicantion in CodeIgniter which needs to be able to send data about a car and a customer to different types of companies using SOAP, maybe XML, comma-separated and so on.
But they all need the same thing.
I wanna make it as dynamic as possible and make sure it's easy to write tests.
So the service should take a couple of things:
a handler
applicants [1-2]
params
object
I started up creating different classes
Gr8Exp
NordCar
SwePerf
each implementing the interface iServiceRequest
interface iServiceRequest{
/**
* Send the request to the company server.
*/
function sendRequest();
/**
* Saves the response into the database.
*/
function saveResponse();
/**
* Prepares the request to the company, setting info from form and shit.
*/
function prepareRequest();
/**
* Soap, XML, CSV, JSON
* #param type $method
*/
function setRequestHandler(iServiceRequestHandler $handler);
}
Then they need to structure up the Soap, XML, CSV, JSON request depending on what handler i put in.
After those who needed to be validated (not all did) I used:
interface iAdaptServiceRequest{
/**
* Structure the array information and put it into an object structure in the right place.
*/
function structure(array $info);
/**
* Make all the checks for the function
*/
function validateInfo();
}
But I'm stuck, It worked really good when I just used SOAP request; but now. Since I need to format them differently, use a different handler for each type of request or company I don't know what to do.
I could put them i different folders and recreate the class in the different folders. But that's not a good practice since I'm duplicating code all over.
In the end I want to run some chaining like this:
$result = $m->prepareRequest()->sendRequest()->saveResponse();
Any suggestions??
IMHO:
-- create/use a front controller.
-- The front controller determines which request handler to use (JSON, SOAP, XML, etc).
-- The request handler generates a common "Request" object that behaves the same across all interfaces, basically putting variables into a common named format inside a "Request object"
-- It determines which service to send the request to and sends the request object there
-- The service processes the request object and generates a response object
-- The controller creates an appropriate (JSON/SOAP/XML) View object to process the response object into the correct view type and the View outputs your response as that type.
I would use something like yours: $result = $m->prepareRequest('JSON')->sendRequest()->saveResponse();, but specifing what format of data I'm sending.
The method prepareRequest(string $type) would check the format and call another method to convert your data to the respective format.
Something like this:
function prepareRequest(string $type){
if ($type == 'json'){
$this->convert2json();
}
if ($type == 'xml'){
$this->convert2xml();
}
// And so on
}
There is often confusion about the MVC or Observer pattern. This is not a situation in which this pattern is applicable. In the MVC pattern are the View and Model related to one another. The View must update itself based on information of the subject. A view and the underlying tables in a database are a good example. That is not what you want here.
The design pattern which suits this problem is the Builder pattern. The Builder pattern consists of four cooperating classtypes:
1. a Builder,
2. a ReaderManager,
3. a ConverterManager, and
4. a DataObject.
The ReaderManager is using the Interpreter pattern. Conversion can be done using the State pattern. What is the output of the ReaderManager (some DataObject) is the input for the ConversionManager. That can be done using an abstract class instead of an interface (my preference for data focused classes). The Builder connects the ReaderManager with the ConverterManager and takes care of the transport of data.
Some years ago I wrote about design patterns. The builder pattern was one of the patterns I described and this is the link to that page:
http://www.loekbergman.nl/InsideArchitecture/TheProcess/DesignPatterns/Builder
It shows a UML diagram of the pattern.
In the next link you can download a jar with some examples of design patterns. One of them the builder pattern:
http://www.loekbergman.nl/InsideArchitecture/DownloadsAndLicense
I have written this code several years ago, therefor do I give you this code without warranty. (Is that the correct term in this context?)
In the code you can see a folder with the name specifications. That is another example of the Interpreter pattern. (In the Builder pattern there is of course also an example of this pattern).
To be complete is here the link to the MVC - pattern:
http://www.loekbergman.nl/InsideArchitecture/TheProcess/DesignPatterns/Observer
and the Interpreter pattern:
http://www.loekbergman.nl/InsideArchitecture/TheProcess/DesignPatterns/Interpreter
Some background: I came from a .Net environment where we had to use MVVM in all of our projects to separate the view from the viewmodel. Now that I'm working on my own personal PHP project I decided to use the same design and separate the view and viewmodel.
So on the view I create a viewmodel object and call background functions when necessary and in the view the code is only to provide the display.
Example:
view.php
<?php
include('viewmodel.php');
$vm = new viewmodel.php();
if(some condition)
{
$vm->doSomething();
}
?>
<html>
<body>
//some form code
</body>
</html>
viewmodel.php
<?php
//includes
class viewmodel
{
function viewmodel()
{
}
function doSomething()
{
}
}
?>
Now that I've learned jQuery I want to use it to make my pages more dynamic, have less traffic back and forth to the server and less need for page refreshing.
I've seen calls like this that allow jQuery to call a php page with some some post data:
$.ajax({ url: '/my/site',
data: {action: 'test'},
type: 'post',
success: function(output) {
alert(output);
}
});
However this is no longer Object Oriented Design and I would have to remove all the class definitions from my viewmodels for this to work.
Is there any way for jQuery to make those calls to the viewmodel or does using jQuery mean you have to return to a procedural style of programming?
However this is no longer Object Oriented Design and I would have to remove all the class definitions from my viewmodels for this to work.
What makes you think that? There's nothing inherently object-oriented or non-object-oriented about making AJAX requests to the server. Nor do these client-originated requests have any bearing on the architecture of the server-side code.
In your views you can have any JavaScript code you'd like. It won't make a difference to the server-side code rendering the view, as the JavaScript is just text as far as it's concerned and no different than the HTML.
As for the server-side handler, what you'll probably want to do is create entirely new views and viewmodels for the "page" ("resource" is a more accurate word) that's being called by the jQuery code.
So, for example, you might get a request from the browser for something like /my/site which would, using the architecture you have in place, populate a viewmodel to bind to a view and return that view to the client. That view would contain some JavaScript code, some of which calls another resource. Let's say that other resource is something like /api/products which returns a list of "products" available for the user.
Note that I put the resource under a different path, api instead of my. This was a pretty arbitrary decision, and it's only used to illustrate that what you're returning in this case isn't a "page" so much as it is JSON data for an automated API. The actual name of the resource can be anything you like, of course.
This resource can still be a view and be bound to a viewmodel, but in this case the view is JSON data instead of HTML. As with anything, there are many ways you can do this. A quick Google search turned up another question which talks about the differences between a couple of methods for generating JSON data. Indeed, your "view" in this case might be entirely empty and all you're doing is serializing a viewmodel to JSON and returning that. (My PHP is pretty rusty, but the ASP.NET MVC equivalent would be to return an ActionResult of Json() instead of View().)
Keep in mind that, from the perspective of the server-side code, there is no difference between returning a view in HTML vs. returning one in JSON (or XML, or raw text, or anything else). A view is a view, each one independent from the others.