Customize prestashop web service - json

Question

I want to customize Prestashop web service for my own usage but I don't know how and I can't find any tutorial. I have a mobile application that want to retrieve data from website but the default web service is useless.
For example I want the list of categories (in a language) with they're pictures but It seems I should call two different service to retrieve categories and images separately.
Assume I want to have a JSON array of categories that a category is a JSON object that have these fields {id,title,imageUrl} but It seems I should get {id,title} with a method and after that I can get images on by one by another method!
I couldn't find any guide for extending or customizing web service in the documentation.

Answer 1

I'm a bit late but:
Prestashop version requier : > 1.6
If you want to customize a web service and return specific fields with a JSON format output. You need to do it this way:
First
In override :
Create a class : myClassForWs that extends myClassCore
Override WebserviceRequest in webservice/WebserviceRequest.php
In webservice/WebserviceRequest.php : Add myClassForWs to
ressources:
public static function getResources()
{
$resources = parent::getResources();
$resources['myClassForWs'] = array('description' => 'The class','class' => 'myClassForWs');
ksort($resources);
return $resources;
}
}
In myClassForWs : redefine $webserviceParameters and $definition with the fields you need:
protected $definition = array(
'table' => 'category',
'primary' => 'id_category',
'multilang' => true,
'multilang_shop' => true,
'fields' => array(
'name' =>array('type' => self::TYPE_STRING, 'lang' => true, 'validate' => 'isCatalogName', 'required' => true, 'size' => 128),
'link_rewrite' =>array('type' => self::TYPE_STRING, 'lang' => true, 'validate' => 'isLinkRewrite', 'required' => true, 'size' => 128),
'description' =>array('type' => self::TYPE_HTML, 'lang' => true, 'validate' => 'isCleanHtml'),
),
);
protected $webserviceParameters = array(
'objectsNodeName' =>'categories',
'hidden_fields'=>array('nleft', 'nright', 'groupBox'),
'fields' => array(
'level_depth' => array('setter' => false),
),
'associations' => array(
'images' => array(
'resource' => 'image',
'fields' => array('id' => array())
),
),
);
Then
Go in your admin tab :
in performance : clear cache
in advanced settings > Web service: active a api Key and set myClassForWs for this key
Finally
Access to your web service with url :
my.prestashop/api/myClassForWs/{id_class}?output_format=**JSON**
And it returns your datas
I hope it helps.