Hierarchy
Ext.data.reader.ReaderExt.data.reader.Json
The JSON Reader is used by a Proxy to read a server response that is sent back in JSON format. This usually +happens as a result of loading a Store - for example we might create something like this:
+ + + + +Ext.define('User', {
+ extend: 'Ext.data.Model',
+ fields: ['id', 'name', 'email']
+});
+
+var store = new Ext.data.Store({
+ model: 'User',
+ proxy: {
+ type: 'ajax',
+ url : 'users.json',
+ reader: {
+ type: 'json'
+ }
+ }
+});
+The example above creates a 'User' model. Models are explained in the Model docs if you're +not already familiar with them.
+ + + + +We created the simplest type of JSON Reader possible by simply telling our Store's +Proxy that we want a JSON Reader. The Store automatically passes the configured model to the +Store, so it is as if we passed this instead: + +
reader: {
+ type : 'json',
+ model: 'User'
+}
+The reader we set up is ready to read data from our server - at the moment it will accept a response like this:
+ +[
+ {
+ "id": 1,
+ "name": "Ed Spencer",
+ "email": "ed@sencha.com"
+ },
+ {
+ "id": 2,
+ "name": "Abe Elias",
+ "email": "abe@sencha.com"
+ }
+]
+Reading other JSON formats
+ +If you already have your JSON format defined and it doesn't look quite like what we have above, you can usually +pass JsonReader a couple of configuration options to make it parse your format. For example, we can use the +root configuration to parse data that comes back like this:
+ +{
+ "users": [
+ {
+ "id": 1,
+ "name": "Ed Spencer",
+ "email": "ed@sencha.com"
+ },
+ {
+ "id": 2,
+ "name": "Abe Elias",
+ "email": "abe@sencha.com"
+ }
+ ]
+}
+To parse this we just pass in a root configuration that matches the 'users' above:
+ +reader: {
+ type: 'json',
+ root: 'users'
+}
+Sometimes the JSON structure is even more complicated. Document databases like CouchDB often provide metadata +around each record inside a nested structure like this:
+ +{
+ "total": 122,
+ "offset": 0,
+ "users": [
+ {
+ "id": "ed-spencer-1",
+ "value": 1,
+ "user": {
+ "id": 1,
+ "name": "Ed Spencer",
+ "email": "ed@sencha.com"
+ }
+ }
+ ]
+}
+In the case above the record data is nested an additional level inside the "users" array as each "user" item has +additional metadata surrounding it ('id' and 'value' in this case). To parse data out of each "user" item in the +JSON above we need to specify the record configuration like this:
+ +reader: {
+ type : 'json',
+ root : 'users',
+ record: 'user'
+}
+Response metadata
+ +The server can return additional data in its response, such as the total number of records +and the success status of the response. These are typically included in the JSON response +like this:
+ +{
+ "total": 100,
+ "success": true,
+ "users": [
+ {
+ "id": 1,
+ "name": "Ed Spencer",
+ "email": "ed@sencha.com"
+ }
+ ]
+}
+If these properties are present in the JSON response they can be parsed out by the JsonReader and used by the +Store that loaded it. We can set up the names of these properties by specifying a final pair of configuration +options:
+ +reader: {
+ type : 'json',
+ root : 'users',
+ totalProperty : 'total',
+ successProperty: 'success'
+}
+These final options are not necessary to make the Reader work, but can be useful when the server needs to report +an error or if it needs to indicate that there is a lot of data available of which only a subset is currently being +returned.
+ +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.
+The optional location within the JSON response that the record data itself can be found at. +See the JsonReader intro docs for more details. This is not often needed and defaults to undefined.
+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.
+True to ensure that field names/mappings are treated as literals when +reading values. Defalts to false. +For example, by default, using the mapping "foo.bar.baz" will try and read a property foo from the root, then a property bar +from foo, then a property baz from bar. Setting the simple accessors to true will read the property with the name +"foo.bar.baz" direct from the root object.
+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
+Reads a JSON object and returns a ResultSet. Uses the internal getTotal and getSuccess extractors to +retrieve meta data from the response, and extractData to turn the JSON data into model instances.
+The raw JSON data
+A ResultSet containing model instances and meta data about the results
+