Properties Methods Events Config Options Direct Link
DataReader
  JsonReader

Class Ext.data.JsonReader

Package:Ext.data
Defined In:JsonReader.js
Class:JsonReader
Extends:DataReader
Data reader class to create an Array of Ext.data.Record objects from a JSON response based on mappings in a provided Ext.data.Record constructor.

Example code:

var Employee = Ext.data.Record.create([
    {name: 'name', mapping: 'name'},     // "mapping" property not needed if it's the same as "name"
    {name: 'occupation'}                 // This field will use "occupation" as the mapping.
]);
var myReader = new Ext.data.JsonReader({
    totalProperty: "results",    // The property which contains the total dataset size (optional)
    root: "rows",                // The property which contains an Array of row objects
    id: "id"                     // The property within each row object that provides an ID for the record (optional)
}, Employee);

This would consume a JSON file like this:

{ 'results': 2, 'rows': [
    { 'id': 1, 'name': 'Bill', occupation: 'Gardener' },
    { 'id': 2, 'name': 'Ben', occupation: 'Horticulturalist' } ]
}

It is possible to change a JsonReader's metadata at any time by including a MetaData property in the data object. If this is detected in the object, a Store object using this Reader will fire its metachange event.

The MetaData property may contain any of the configuration options for this class. Additionally, it may contain a fields property which the JsonReader will use that as an argument to Ext.data.Record.create to configure the layout of the Records which it will produce.

Using the MetaData property, and the Store's metachange event, it is possible to have a Store-driven control initialize itself. The metachange event handler may interrogate the MetaData property (which may contain any user-defined properties needed) and the MetaData.fields property to perform any configuration required.

To use this facility to send the same data as the above example without having to code the creation of the Record constructor, you would create the JsonReader like this:

var myReader = new Ext.data.JsonReader();

The first data packet from the server would configure the reader by containing a metaData property as well as the data:

{
  'metaData': {
    totalProperty: 'results',
    root: 'rows',
    id: 'id',
    fields: [
      {name: 'name'},
      {name: 'occupation'} ]
   },
  'results': 2, 'rows': [
    { 'id': 1, 'name': 'Bill', occupation: 'Gardener' },
    { 'id': 2, 'name': 'Ben', occupation: 'Horticulturalist' } ]
}

Config Options

Config Options Defined By
  id : String
Name of the property within a row object that contains a record identifier value.
JsonReader
  root : String
name of the property which contains the Array of row objects.
JsonReader
  successProperty : String
Name of the property from which to retrieve the success attribute used by forms.
JsonReader

Public Properties

Property Defined By
  meta : Mixed
This JsonReader's metadata as passed to the constructor, or as passed in the last data packet's MetaData property.
JsonReader

Public Methods

Method Defined By

Public Events

This class has no public events.