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
-