/**
+ * @author Ed Spencer
+ * @class Ext.data.proxy.Ajax
+ * @extends Ext.data.proxy.Server
+ *
+ * <p>AjaxProxy is one of the most widely-used ways of getting data into your application. It uses AJAX requests to
+ * load data from the server, usually to be placed into a {@link Ext.data.Store Store}. Let's take a look at a typical
+ * setup. Here we're going to set up a Store that has an AjaxProxy. To prepare, we'll also set up a
+ * {@link Ext.data.Model Model}:</p>
+ *
+<pre><code>
+Ext.define('User', {
+ extend: 'Ext.data.Model',
+ fields: ['id', 'name', 'email']
+});
+
+//The Store contains the AjaxProxy as an inline configuration
+var store = new Ext.data.Store({
+ model: 'User',
+ proxy: {
+ type: 'ajax',
+ url : 'users.json'
+ }
+});
+
+store.load();
+</code></pre>
+ *
+ * <p>Our example is going to load user data into a Store, so we start off by defining a {@link Ext.data.Model Model}
+ * with the fields that we expect the server to return. Next we set up the Store itself, along with a {@link #proxy}
+ * configuration. This configuration was automatically turned into an Ext.data.proxy.Ajax instance, with the url we
+ * specified being passed into AjaxProxy's constructor. It's as if we'd done this:</p>
+ *
+<pre><code>
+new Ext.data.proxy.Ajax({
+ url: 'users.json',
+ model: 'User',
+ reader: 'json'
+});
+</code></pre>
+ *
+ * <p>A couple of extra configurations appeared here - {@link #model} and {@link #reader}. These are set by default
+ * when we create the proxy via the Store - the Store already knows about the Model, and Proxy's default
+ * {@link Ext.data.reader.Reader Reader} is {@link Ext.data.reader.Json JsonReader}.</p>
+ *
+ * <p>Now when we call store.load(), the AjaxProxy springs into action, making a request to the url we configured
+ * ('users.json' in this case). As we're performing a read, it sends a GET request to that url (see {@link #actionMethods}
+ * to customize this - by default any kind of read will be sent as a GET request and any kind of write will be sent as a
+ * POST request).</p>
+ *
+ * <p><u>Limitations</u></p>
+ *
+ * <p>AjaxProxy cannot be used to retrieve data from other domains. If your application is running on http://domainA.com
+ * it cannot load data from http://domainB.com because browsers have a built-in security policy that prohibits domains
+ * talking to each other via AJAX.</p>
+ *
+ * <p>If you need to read data from another domain and can't set up a proxy server (some software that runs on your own
+ * domain's web server and transparently forwards requests to http://domainB.com, making it look like they actually came
+ * from http://domainA.com), you can use {@link Ext.data.proxy.JsonP} and a technique known as JSON-P (JSON with
+ * Padding), which can help you get around the problem so long as the server on http://domainB.com is set up to support
+ * JSON-P responses. See {@link Ext.data.proxy.JsonP JsonPProxy}'s introduction docs for more details.</p>
+ *
+ * <p><u>Readers and Writers</u></p>
+ *
+ * <p>AjaxProxy can be configured to use any type of {@link Ext.data.reader.Reader Reader} to decode the server's response. If
+ * no Reader is supplied, AjaxProxy will default to using a {@link Ext.data.reader.Json JsonReader}. Reader configuration
+ * can be passed in as a simple object, which the Proxy automatically turns into a {@link Ext.data.reader.Reader Reader}
+ * instance:</p>
+ *
+<pre><code>
+var proxy = new Ext.data.proxy.Ajax({
+ model: 'User',
+ reader: {
+ type: 'xml',
+ root: 'users'
+ }
+});
+
+proxy.getReader(); //returns an {@link Ext.data.reader.Xml XmlReader} instance based on the config we supplied
+</code></pre>
+ *
+ * <p><u>Url generation</u></p>
+ *
+ * <p>AjaxProxy automatically inserts any sorting, filtering, paging and grouping options into the url it generates for
+ * each request. These are controlled with the following configuration options:</p>
+ *
+ * <ul style="list-style-type: disc; padding-left: 20px;">
+ * <li>{@link #pageParam} - controls how the page number is sent to the server
+ * (see also {@link #startParam} and {@link #limitParam})</li>
+ * <li>{@link #sortParam} - controls how sort information is sent to the server</li>
+ * <li>{@link #groupParam} - controls how grouping information is sent to the server</li>
+ * <li>{@link #filterParam} - controls how filter information is sent to the server</li>
+ * </ul>
+ *
+ * <p>Each request sent by AjaxProxy is described by an {@link Ext.data.Operation Operation}. To see how we can
+ * customize the generated urls, let's say we're loading the Proxy with the following Operation:</p>
+ *
+<pre><code>
+var operation = new Ext.data.Operation({
+ action: 'read',
+ page : 2
+});
+</code></pre>
+ *
+ * <p>Now we'll issue the request for this Operation by calling {@link #read}:</p>
+ *
+<pre><code>
+var proxy = new Ext.data.proxy.Ajax({
+ url: '/users'
+});
+
+proxy.read(operation); //GET /users?page=2
+</code></pre>
+ *
+ * <p>Easy enough - the Proxy just copied the page property from the Operation. We can customize how this page data is
+ * sent to the server:</p>
+ *
+<pre><code>
+var proxy = new Ext.data.proxy.Ajax({
+ url: '/users',
+ pagePage: 'pageNumber'
+});
+
+proxy.read(operation); //GET /users?pageNumber=2
+</code></pre>
+ *
+ * <p>Alternatively, our Operation could have been configured to send start and limit parameters instead of page:</p>
+ *
+<pre><code>
+var operation = new Ext.data.Operation({
+ action: 'read',
+ start : 50,
+ limit : 25
+});
+
+var proxy = new Ext.data.proxy.Ajax({
+ url: '/users'
+});
+
+proxy.read(operation); //GET /users?start=50&limit=25
+</code></pre>
+ *
+ * <p>Again we can customize this url:</p>
+ *
+<pre><code>
+var proxy = new Ext.data.proxy.Ajax({
+ url: '/users',
+ startParam: 'startIndex',
+ limitParam: 'limitIndex'
+});
+
+proxy.read(operation); //GET /users?startIndex=50&limitIndex=25
+</code></pre>
+ *
+ * <p>AjaxProxy will also send sort and filter information to the server. Let's take a look at how this looks with a
+ * more expressive Operation object:</p>
+ *
+<pre><code>
+var operation = new Ext.data.Operation({
+ action: 'read',
+ sorters: [
+ new Ext.util.Sorter({
+ property : 'name',
+ direction: 'ASC'
+ }),
+ new Ext.util.Sorter({
+ property : 'age',
+ direction: 'DESC'
+ })
+ ],
+ filters: [
+ new Ext.util.Filter({
+ property: 'eyeColor',
+ value : 'brown'
+ })
+ ]
+});
+</code></pre>
+ *
+ * <p>This is the type of object that is generated internally when loading a {@link Ext.data.Store Store} with sorters
+ * and filters defined. By default the AjaxProxy will JSON encode the sorters and filters, resulting in something like
+ * this (note that the url is escaped before sending the request, but is left unescaped here for clarity):</p>
+ *
+<pre><code>
+var proxy = new Ext.data.proxy.Ajax({
+ url: '/users'
+});
+
+proxy.read(operation); //GET /users?sort=[{"property":"name","direction":"ASC"},{"property":"age","direction":"DESC"}]&filter=[{"property":"eyeColor","value":"brown"}]
+</code></pre>
+ *
+ * <p>We can again customize how this is created by supplying a few configuration options. Let's say our server is set
+ * up to receive sorting information is a format like "sortBy=name#ASC,age#DESC". We can configure AjaxProxy to provide
+ * that format like this:</p>
+ *
+ <pre><code>
+ var proxy = new Ext.data.proxy.Ajax({
+ url: '/users',
+ sortParam: 'sortBy',
+ filterParam: 'filterBy',
+
+ //our custom implementation of sorter encoding - turns our sorters into "name#ASC,age#DESC"
+ encodeSorters: function(sorters) {
+ var length = sorters.length,
+ sortStrs = [],
+ sorter, i;
+
+ for (i = 0; i < length; i++) {
+ sorter = sorters[i];
+
+ sortStrs[i] = sorter.property + '#' + sorter.direction
+ }
+
+ return sortStrs.join(",");
+ }
+ });
+
+ proxy.read(operation); //GET /users?sortBy=name#ASC,age#DESC&filterBy=[{"property":"eyeColor","value":"brown"}]
+ </code></pre>
+ *
+ * <p>We can also provide a custom {@link #encodeFilters} function to encode our filters.</p>
+ *
+ * @constructor
+ *
+ * <p>Note that if this HttpProxy is being used by a {@link Ext.data.Store Store}, then the
+ * Store's call to {@link #load} will override any specified <tt>callback</tt> and <tt>params</tt>
+ * options. In this case, use the Store's {@link Ext.data.Store#events events} to modify parameters,
+ * or react to loading events. The Store's {@link Ext.data.Store#baseParams baseParams} may also be
+ * used to pass parameters known at instantiation time.</p>
+ *
+ * <p>If an options parameter is passed, the singleton {@link Ext.Ajax} object will be used to make
+ * the request.</p>
+ */
+Ext.define('Ext.data.proxy.Ajax', {
+ requires: ['Ext.util.MixedCollection', 'Ext.Ajax'],
+ extend: 'Ext.data.proxy.Server',
+ alias: 'proxy.ajax',
+ alternateClassName: ['Ext.data.HttpProxy', 'Ext.data.AjaxProxy'],
+
+ /**
+ * @property actionMethods
+ * Mapping of action name to HTTP request method. In the basic AjaxProxy these are set to 'GET' for 'read' actions and 'POST'
+ * for 'create', 'update' and 'destroy' actions. The {@link Ext.data.proxy.Rest} maps these to the correct RESTful methods.
+ */
+ actionMethods: {
+ create : 'POST',
+ read : 'GET',
+ update : 'POST',
+ destroy: 'POST'
+ },
+
+ /**
+ * @cfg {Object} headers Any headers to add to the Ajax request. Defaults to <tt>undefined</tt>.
+ */
+
+ /**
+ * @ignore
+ */
+ doRequest: function(operation, callback, scope) {
+ var writer = this.getWriter(),
+ request = this.buildRequest(operation, callback, scope);
+
+ if (operation.allowWrite()) {
+ request = writer.write(request);
+ }
+
+ Ext.apply(request, {
+ headers : this.headers,
+ timeout : this.timeout,
+ scope : this,
+ callback : this.createRequestCallback(request, operation, callback, scope),
+ method : this.getMethod(request),
+ disableCaching: false // explicitly set it to false, ServerProxy handles caching
+ });
+
+ Ext.Ajax.request(request);
+
+ return request;
+ },
+
+ /**
+ * Returns the HTTP method name for a given request. By default this returns based on a lookup on {@link #actionMethods}.
+ * @param {Ext.data.Request} request The request object
+ * @return {String} The HTTP method to use (should be one of 'GET', 'POST', 'PUT' or 'DELETE')
+ */
+ getMethod: function(request) {
+ return this.actionMethods[request.action];
+ },
+
+ /**
+ * @private
+ * TODO: This is currently identical to the JsonPProxy version except for the return function's signature. There is a lot
+ * of code duplication inside the returned function so we need to find a way to DRY this up.
+ * @param {Ext.data.Request} request The Request object
+ * @param {Ext.data.Operation} operation The Operation being executed
+ * @param {Function} callback The callback function to be called when the request completes. This is usually the callback
+ * passed to doRequest
+ * @param {Object} scope The scope in which to execute the callback function
+ * @return {Function} The callback function
+ */
+ createRequestCallback: function(request, operation, callback, scope) {
+ var me = this;
+
+ return function(options, success, response) {
+ me.processResponse(success, operation, request, response, callback, scope);
+ };
+ }
+}, function() {
+ //backwards compatibility, remove in Ext JS 5.0
+ Ext.data.HttpProxy = this;
+});
+