Readers are used to interpret data to be loaded into a Model instance or a Store -- usually in response to an AJAX request. This is normally handled transparently by passing some configuration to either the -Model or the Store in question - see their documentation for further details.
- - - - -Loading Nested Data
- - - - -Readers have the ability to automatically load deeply-nested data objects based on the associations -configured on each Model. Below is an example demonstrating the flexibility of these associations in a fictional CRM system which -manages a User, their Orders, OrderItems and Products. First we'll define the models: - -
Ext.define("User", {
- extend: 'Ext.data.Model',
- fields: [
- 'id', 'name'
- ],
-
- hasMany: {model: 'Order', name: 'orders'},
-
- proxy: {
- type: 'rest',
- url : 'users.json',
- reader: {
- type: 'json',
- root: 'users'
- }
- }
-});
-
-Ext.define("Order", {
- extend: 'Ext.data.Model',
- fields: [
- 'id', 'total'
- ],
-
- hasMany : {model: 'OrderItem', name: 'orderItems', associationKey: 'order_items'},
- belongsTo: 'User'
-});
-
-Ext.define("OrderItem", {
- extend: 'Ext.data.Model',
- fields: [
- 'id', 'price', 'quantity', 'order_id', 'product_id'
- ],
-
- belongsTo: ['Order', {model: 'Product', associationKey: 'product'}]
-});
-
-Ext.define("Product", {
- extend: 'Ext.data.Model',
- fields: [
- 'id', 'name'
- ],
-
- hasMany: 'OrderItem'
-});
-This may be a lot to take in - basically a User has many Orders, each of which is composed of several OrderItems. Finally, -each OrderItem has a single Product. This allows us to consume data like this:
- -{
- "users": [
- {
- "id": 123,
- "name": "Ed",
- "orders": [
- {
- "id": 50,
- "total": 100,
- "order_items": [
- {
- "id" : 20,
- "price" : 40,
- "quantity": 2,
- "product" : {
- "id": 1000,
- "name": "MacBook Pro"
- }
- },
- {
- "id" : 21,
- "price" : 20,
- "quantity": 3,
- "product" : {
- "id": 1001,
- "name": "iPhone"
- }
- }
- ]
- }
- ]
- }
- ]
-}
-The JSON response is deeply nested - it returns all Users (in this case just 1 for simplicity's sake), all of the Orders -for each User (again just 1 in this case), all of the OrderItems for each Order (2 order items in this case), and finally -the Product associated with each OrderItem. Now we can read the data and use it as follows: - -
var store = new Ext.data.Store({
- model: "User"
-});
-
-store.load({
- callback: function() {
- //the user that was loaded
- var user = store.first();
-
- console.log("Orders for " + user.get('name') + ":")
-
- //iterate over the Orders for each User
- user.orders().each(function(order) {
- console.log("Order ID: " + order.getId() + ", which contains items:");
-
- //iterate over the OrderItems for each Order
- order.orderItems().each(function(orderItem) {
- //we know that the Product data is already loaded, so we can use the synchronous getProduct
- //usually, we would use the asynchronous version (see Ext.data.BelongsToAssociation)
- var product = orderItem.getProduct();
-
- console.log(orderItem.get('quantity') + ' orders of ' + product.get('name'));
- });
- });
- }
-});
-Running the code above results in the following:
- -Orders for Ed:
-Order ID: 50, which contains items:
-2 orders of MacBook Pro
-3 orders of iPhone
-Name of the property within a row object -that contains a record identifier value. Defaults to The id of the model. -If an idProperty is explicitly specified it will override that of the one specified -on the model
-True to automatically parse models nested within other models in a response -object. See the Ext.data.reader.Reader intro docs for full explanation. Defaults to true.
-The name of the property which contains a response message. -This property is optional.
-The name of the property which contains a response message. -This property is optional.
-Required. The name of the property -which contains the Array of row objects. Defaults to undefined. -An exception will be thrown if the root property is undefined. The data -packet value for this property should be an empty array to clear the data -or show no data.
-Name of the property from which to -retrieve the success attribute. Defaults to success. See -Ext.data.proxy.Proxy.exception -for additional information.
-Name of the property from which to -retrieve the total number of records in the dataset. This is only needed -if the whole dataset is not passed in one go, but is being paged from -the remote server. Defaults to total.
-Takes a raw response object (as passed to this.read) and returns the useful data segment of it. This must be implemented by each subclass
-The responce object
-The useful data from the response
-Reads the given response object. This method normalizes the different types of response object that may be passed -to it, before handing off the reading of records to the readRecords function.
-The response object. This may be either an XMLHttpRequest object or a plain JS object
-The parsed ResultSet object
-Abstracts common functionality used by all Reader subclasses. Each subclass is expected to call -this function before running its own logic and returning the Ext.data.ResultSet instance. For most -Readers additional processing should not be needed.
-The raw data object
-A ResultSet object
-