Drupal with Android integration: make posts and upload photos. Part I - Drupal.

Drupal is powerful and popular web CMS, with many useful features and hundreds of different modules that can extend core functionality. Android is powerful, popular and very fast growing mobile platform. It's leading smartphone and tablets platform. In this article i'll show you how to integrate Drupal with Android powered mobile devices, to authorize on site and to perform some actions. 

If you are interested in development mobile applications, that can backup or store files to a website, upload photos, make posts, administer site, or perform other remote actions - this article is for you. Here you can find guidelines and principles description of how mobile and web integration can be made. 

Example in this article will be a practical task: post pages and upload photos from Android device to Drupal website. In example, i show how to use it with Drupal 6, but all is also applicable to Drupal 7 (only minor modifications of Drupal module are required). This article show how to integrate Drupal with Android OS. If you need another platform, it can be useful for you too, as it describes principles and issues of communication. 

How it will be done?

Our task is to perform actions on Drupal website, and we need a method to communicate with it.
We will use XML-RPC protocol for communication between Android and Drupal. It's lightweight remote procedure call protocol, and you don't need any additional knowledge, as with SOAP. Also, it's not require  interface definitions, as with SOAP.

To use it, we need services module (http://drupal.org/project/services).

1. Services module

This module allows to create services within Drupal modules. A service exposes a set of methods, that can be called remotely by third party applications. Each method has defined name, parameters and return type. In our case they will be called from Android-powered mobile device.

Services module supports many communication protocols. REST, XMLRPC, JSON, JSON-RPC, SOAP, AMF are supported. 

In this example we will use XMLRPC.

2. Configuring services module

Services module is not included in Drupal core. So, you need to download it from http://drupal.org/project/services. Unpack it into your Drupal website modules subdirectory (sites/all/modules), and enable it in modules administration page.

If all is fine, you will see it in modules admin page.

Next, you need to define the service endpoint. Open the services admin page of your site, and add "android" endpoint:

Then click "Add" link:

And then, enter endpoint's parameters:  machine-readable name, server type and endpoint path. 
Session authentication must be checked. If it's unchecked, all rpc calls will be executed as anonymous user.
Example is shown below:

Next, open resources tab. And select resouces, that will be available through this endpoint.

Resources are nodes, comments, files, users, etc. You need to enable user login and logout, and node create and delete. You can enable more resouces. For example: to allow users registration from mobile, to add/remove comments and etc. But, it's good practice to allow only that's really needed. (For example, if you use captcha for users registration to block bots, enabling user.register method through services will allow them to avoid captcha).

Now, services module is configured.

3. Drupal module

The purpose of our module is to get uploads from Android devices and attach them to pages. 
We call our module "photoupload". Create subdirectory photoupload in sites/all/modules directory of Drupal. Now we create photoupload.info. Set up mandatory fields:

name = Photo upload
description = Module that manages photo uploads from Android devices

core = 6.x
version = "6.x-1.0"
project = "photoupload"

Now, create module file photoupload.module. 

Begin with php opening tag.

 <?php 

First, our module will define "upload photos" permission. Only users with this permission are allowed to upload photos.

function photoupload_perm() 
{
 return array('upload photos');
}

Next, we need to define menu item for uploads. Call it "photoupload". Menu item is needed to handle urls, so it will be hidden (callback). Upload is made through form, so define page callback to be drupal_get_form, page arguments as array containing name of function to create form. Access arguments is array containing permission, required for access to menu item. In this case, it will an array with "upload photos" element.

function photoupload_menu() 

{
 $items = array();

 // mobile photo upload
 $items['photoupload'] = array(
  'title' => 'Mobile photo upload',
  'description' => 'Upload photo',
  // setup page callback to return form
  'page callback' => 'drupal_get_form',
  // form function
  'page arguments' => array('photoupload_upload_file'),
  // users with 'upload photos' permission is only allowed
  'access arguments' => array('upload photos'),
  // hide it from menus, available to users
  'type' => MENU_CALLBACK, 
 );
 return $items;
}

Now, we create form for upload. It will contain image file and page node identifier elements.

function photoupload_upload_file($form_state)

{
 // prepare the file upload form
 // set multipart/form-data encoding type
 $form = array('#attributes' => array('enctype' => 'multipart/form-data'));

 // image file selector
 $form['image'] = array(
     '#type' => 'file',
     '#title' => 'Upload photo',
     '#description' => t('Pick a image file to upload')
 );

 // page node identifier. The page to image be attached
 $form['nid'] = array(
  '#type' => 'textfield',
  '#title' => 'Page nid',
 );

 $form['#token'] = FALSE;
 
 // submit button
 $form['submit'] = array('#type' => 'submit', '#value' => 'Upload');
 return $form;
}

Create form submission handler.

function photoupload_upload_file_submit($form, &$form_state)
{
 $dir = file_directory_path();
 
 // unlike form submissions, multipart form submissions are not in
 // $form_state, but rather in $FILES, which requires more checking
 //

 if (!isset($_FILES) || empty($_FILES) || $_FILES['files']['size']['image'] == 0) {
      drupal_set_message("Your file doesn't appear to be here.");
  return ;
 }

 $name = $_FILES['files']['name']['image'];
 $size = $_FILES['files']['size']['image'];
 $type = $_FILES['files']['type']['image'];

 // get page nid
 $nid = $form_state['values']['nid'];

 // this is the actual place where we store the file
 $file = file_save_upload('image', array() , $dir);
 if ($file) {
  $filename = $dir."/".$file->filename;

  $import = _photoupload_attach_photo($filename, $nid);
  drupal_set_message($import); 
 }
 else {
     drupal_set_message("Something went wrong saving your file.");
 }
}

Add function to attach photo to page.

function _photoupload_attach_photo($file, $nid)
{
 global $user;

 // load node by nid
 $node = node_load($nid);

 // create file object
 $name = basename($file);

 $file_obj = new stdClass();
 $file_obj->filename = $name;
 $file_obj->filepath = $file;
 $file_obj->filemime = file_get_mimetype($name);
 $file_obj->filesize = $stats['size'];
 $file_obj->filesource = $file;
 $file_obj->status = FILE_STATUS_TEMPORARY;
 $file_obj->timestamp = time();
 $file_obj->list = 1;
 $file_obj->new = true;

 // write it
 drupal_write_record('files', $file_obj);

 file_set_status($file_obj, 1);
 // attach file to node

 $node->files[$file_obj->fid] = $file_obj;

 // and finally, save node
 node_save($node);
 return "OK";
}

And php closing tag.

?>

We finished with Drupal's module code.

Now, you need enable it in modules administration page.

It's all done with Drupal part. In the next part of article i'll describe how to implement Android application.
Drupal with Android integration: make posts and upload photos. Part II - Android.