Extending Magento REST Api with a custom module fails on route

Question

Running Magento V1.9 with Rest API

I can extract data using the REST api, but I need to exctract a list of categories and might even have the ability to add a new category through the API.

I have tried creating an module inside local and community folders, but I have this response returned.

exception 'Mage_Api2_Exception' with message 'Request does not match any route.'

QUESTION: Could it be caused by an error in my folder structure?

Inside api2.xml i think, theres must be a match between the route section and my call the API.

CALL: magentohosturl/api/rest/restapi/categories

Route section from api2.xml

 <routes>                
      <route_entity>
          <route>/restapi/categories/:cat_id</route>
          <action_type>entity</action_type>
      </route_entity>
      <route_collection>
           <route>/restapi/categories</route>
           <action_type>collection</action_type>
      </route_collection>
  </routes>

Question: Is there something I might have overlooked that effects the route?

Full api2.xml file

<?xml version="1.0"?>
<config>
<api2>
    <resource_groups>
        <catalog translate="title" module="RestApi_Categories">
            <title>Category Rest API extension</title>
            <sort_order>10</sort_order>       
        </catalog>
    </resource_groups>
    <resources>
        <categories translate="title" module="RestApi_Categories">
            <group>category</group>
            <model>categories/api2_categories</model>
            <title>Categories retrieval</title>
            <sort_order>10</sort_order>
            <privileges>
                <admin>
                    <retrieve>1</retrieve>
              <!--  <create>1</create>
                    <update>1</update>
                    <delete>1</delete>  --> 
                </admin>               
            </privileges>
            <attributes translate="entity_id name parent_id child_id is_active level position" module="RestApi_Categories">
                <entity_id>Category ID</entity_id>
                <name>Name</name>
                <parent_id>Category Parent ID</parent_id>
                <child_id>Category Child List</child_id>
                <is_active>Active</is_active>
                <level>Level</level>
                <position>Position</position>
            </attributes>
            <routes>                
                <route_entity>
                        <route>/restapi/categories/:cat_id</route>
                        <action_type>entity</action_type>
                    </route_entity>
                <route_collection>
                        <route>/restapi/categories</route>
                        <action_type>collection</action_type>
                </route_collection>
            </routes>           
            <versions>1</versions>
        </categories>
    </resources>
</api2>
</config>

QUESTION: How do I check wether the file is loaded or not?

Filepath: \app\code\community\RestApi\Categories\etc

Followed this guide to enable developer debug mode. http://www.blog.magepsycho.com/configuring-magento-for-development-debug-mode/

Routes from Api2 files is loaded here in function getRoutes($apiType): \app\code\core\Mage\Api2\Model\Config.php

Exception log contains an error message if my api2.xml is manpulated to fail.

Errors message is also present in returned answer from Magento API, so I can confirm my api2.xml is loaded and validates, but the contained routes inside, must be wrong.

Since I've found the routes function I should be able to debug what happens.

Answer 1

Route must look like this rest/api/categories and not just /categories

Now it's resources that fails, so I will provide a full copy, if I get there :)

Thanks Marius for input