Metadata object handling in Laravel [closed] - php

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I need to develop a custom form generator using Laravel.
That means there will be a GUI to select and customise the forms like Registration Form or Booking Form.User should be able to add/edit/delete different form controls, define it as mandatory, etc.
Here I am little confused to handle this in back-end. What is the better way to achieve this?
Or how can I implement a database architecture to use some metadata table which can be used to handle multiple items like Wordpress and is there any built-in Laravel functionalities to handle these meta objects?
And how the insert/update/delete handled in this metadata approach?
Here an insert should have only one row in the meta table. Suppose at the time of user registration, without saving the firstname and lastname in separate rows in the meta table, it should use some objects like this in a single row.
a:3:{s:9:"firstname";s:10:"irshad.far";s:8:"lastname";s:0:"";s:5:"_meta";a:7:{s:2:"ip";s:10:"14.99.80.3";s:9:"confirmip";s:10:"14.99.80.3";s:11:"confirmtime";d:1407932201;s:8:"signupip";s:10:"14.99.80.3";s:10:"signuptime";d:1407932201;s:4:"lang";s:2:"en";s:4:"form";s:7:"unknown";}}

Answer 1

Handling a table of meta data is fairly straight forward using Laravel's Eloquent relations. Let's say you have a users table in your database that contains:
id email password created_at updated_at deleted_at
If you want to keep it simple and not add all sorts of extra data to your users table you could create a meta table and then a link table user_meta to relate the two.
But what if you also have a posts table (as with Wordpress) and your posts also need meta data? Instead of also creating a posts_meta table to link your posts to their meta, we can use Laravels Eloquent relations and create some Polymorphic Relations.
The Database
Here's our setup, along with our users table (above) we have a posts table which has the fields:
id title content created_at updated_at deleted_at
We also have our meta table that follows the guidelines for a polymorphic relation:
id name value metable_id metable_type
//int meta key meta value post/user id resource ie post/user
Using this we could add meta for a post or user to our meta table like this:
id name value metable_id metable_type
------------------------------------------------------
1 nickname Steve 1 User
2 author Steve O 1 Post
All we need to do to grab this info from the database is define the relations in our respective models.
The Models
So now we have our DB ready we need to setup our models (one model for User, one for Post and one for Meta) with our polymorphic relationship. Our User and Post models are both going to use the same function to relate to our Meta model:
User.php
========================================
class User extends Eloquent {
public function meta()
{
return $this->morphMany('Meta', 'metable');
}
}
Post.php
========================================
class Post extends Eloquent {
public function meta()
{
return $this->morphMany('Meta', 'metable');
}
}
Now we define the inverse of those relations in our meta model:
Meta.php
========================================
class Meta extends Eloquent {
public function metable()
{
return $this->morphTo();
}
}
That's it!
Getting the data
Now all you need to do to get at the meta data for a user or post is:
// Load in a post with an id of 1 and get all it's related meta
$post = Post::find(1);
$meta = $post->meta;
If we were to return the meta object we might see something like:
[{"id":2,"metable_id":1,"metable_type":"Post","name":"author","value":"Steve O"}]
Onwards!
From here you can create helper functions like this one that checks if the meta you're after exists in the results:
public function hasMeta($key)
{
$meta = $this->meta;
foreach ($meta as $item):
if( $item->name == $key ) return true;
endforeach;
return false;
}
// Use it like:
if($post->hasMeta('author')){
// Display author
}
Read more about Laravels Eloquent relationships in the docs here: http://laravel.com/docs/eloquent-relationships

Answer 2

I once did something similar, my approach was to build a mini DB engine where forms are like tables and data is rows:
A form which describes the structure and design of a form:
Form {
id,
title,
layout,
...
}
Fields of the form with types and validation rules
Field {
formId,
name,
type (String, Date, Image, Integer, Double, List, ...),
pattern (Regex validation maybe),
...
}
Inserted data in a form is a row belonging to that form
Row {
id,
formId,
}
Each row is a group of entries to fields of the corresponding form that can be validated following the predefined rules.
Entry {
rowId,
fieldId,
value
}
Type and rules can be regrouped in another object so you can have dynamic types that you can manage.
Lists can have another object that stores choices and type of list (multi-select, mono-select)

Answer 3

Metadataobjects itself would be saved in one table. But performance-wise I think those object should their own data tables.
Approach 1)
These types of forms needs to be predefined and linked to a specific controller. This must be either so that there is only one controller for each type of form like Registeration, and only one user defined metadataobject can be in use at either time. This controller's table parameter would be set to point to a database table created specifically for that metadataobject (or perhaps same table could be migrated according to metadata but then that table should be empty).
Or 2) every metadataobject should have it's own controller created which points to the object's data table.
In each approach routes needs to be created to point to the one controller of each type at use in each time.
One dilemma is how to manage revisions of those objects. Perhaps each object might have a running number postfix, and have their own controllers and data tables created (then it might be easier to migrate even populated tables [then user would be notified on front-end if his action would result in data loss, like for example with deleting a form data field]).
Another part of this project is to create an intelligent generator engine for assembling the HTML, CSS, and JS code according to a metadataobject. The generated code can be saved to reside in the same table as the objects themselves, and when used should be cached in the backend for rendering views.
Such metadataobject must itself have a clever format, so that it composes of predefined pieces of settings which will be converted to functionality by the form generator code.