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/*
* Ext JS Library 2.0.2
* Copyright(c) 2006-2008, Ext JS, LLC.
* licensing@extjs.com
*
* http://extjs.com/license
*/
/**
* @class Ext.data.JsonReader
* @extends Ext.data.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.<br>
* <p>
* Example code:
* <pre><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);
</code></pre>
* <p>
* This would consume a JSON file like this:
* <pre><code>
{ 'results': 2, 'rows': [
{ 'id': 1, 'name': 'Bill', occupation: 'Gardener' },
{ 'id': 2, 'name': 'Ben', occupation: 'Horticulturalist' } ]
}
</code></pre>
* <p>It is possible to change a JsonReader's metadata at any time by including a
* <b><tt>MetaData</tt></b> property in the data object. If this is detected in the
* object, a {@link Ext.data.Store Store} object using this Reader will fire its
* {@link Ext.data.Store#metachange metachange} event.</p>
* <p>The <b><tt>MetaData</tt></b> property may contain any of the configuration
* options for this class. Additionally, it may contain a <b><tt>fields</tt></b>
* property which the JsonReader will use that as an argument to {@link Ext.data.Record.create}
* to configure the layout of the Records which it will produce.<p>
* Using the <b><tt>MetaData</tt></b> property, and the Store's {@link Ext.data.Store#metachange metachange} event,
* it is possible to have a Store-driven control initialize itself. The metachange
* event handler may interrogate the <b><tt>MetaData</tt></b> property (which
* may contain any user-defined properties needed) and the <b><tt>MetaData.fields</tt></b>
* property to perform any configuration required.</p>
* <p>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:</p><pre><code>
var myReader = new Ext.data.JsonReader();
</code></pre>
* <p>The first data packet from the server would configure the reader by
* containing a metaData property as well as the data:</p><pre><code>
{
'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' } ]
}
</code></pre>
* @cfg {String} totalProperty 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.
* @cfg {String} successProperty Name of the property from which to retrieve the success attribute used by forms.
* @cfg {String} root name of the property which contains the Array of row objects.
* @cfg {String} id Name of the property within a row object that contains a record identifier value.
* @constructor
* Create a new JsonReader
* @param {Object} meta Metadata configuration options.
* @param {Object} recordType Either an Array of field definition objects as passed to
* {@link Ext.data.Record#create}, or a {@link Ext.data.Record Record} constructor created using {@link Ext.data.Record#create}.
*/
Ext.data.JsonReader = function(meta, recordType){
meta = meta || {};
Ext.data.JsonReader.superclass.constructor.call(this, meta, recordType || meta.fields);
};
Ext.extend(Ext.data.JsonReader, Ext.data.DataReader, {
/**
* This JsonReader's metadata as passed to the constructor, or as passed in
* the last data packet's <b><tt>MetaData</tt></b> property.
* @type Mixed
* @property meta
*/
/**
* This method is only used by a DataProxy which has retrieved data from a remote server.
* @param {Object} response The XHR object which contains the JSON data in its responseText.
* @return {Object} data A data block which is used by an Ext.data.Store object as
* a cache of Ext.data.Records.
*/
read : function(response){
var json = response.responseText;
var o = eval("("+json+")");
if(!o) {
throw {message: "JsonReader.read: Json object not found"};
}
if(o.metaData){
delete this.ef;
this.meta = o.metaData;
this.recordType = Ext.data.Record.create(o.metaData.fields);
this.onMetaChange(this.meta, this.recordType, o);
}
return this.readRecords(o);
},
// private function a store will implement
onMetaChange : function(meta, recordType, o){
},
/**
* @ignore
*/
simpleAccess: function(obj, subsc) {
return obj[subsc];
},
/**
* @ignore
*/
getJsonAccessor: function(){
var re = /[\[\.]/;
return function(expr) {
try {
return(re.test(expr))
? new Function("obj", "return obj." + expr)
: function(obj){
return obj[expr];
};
} catch(e){}
return Ext.emptyFn;
};
}(),
/**
* Create a data block containing Ext.data.Records from a JSON object.
* @param {Object} o An object which contains an Array of row objects in the property specified
* in the config as 'root, and optionally a property, specified in the config as 'totalProperty'
* which contains the total size of the dataset.
* @return {Object} data A data block which is used by an Ext.data.Store object as
* a cache of Ext.data.Records.
*/
readRecords : function(o){
/**
* After any data loads, the raw JSON data is available for further custom processing. If no data is
* loaded or there is a load exception this property will be undefined.
* @type Object
*/
this.jsonData = o;
var s = this.meta, Record = this.recordType,
f = Record.prototype.fields, fi = f.items, fl = f.length;
// Generate extraction functions for the totalProperty, the root, the id, and for each field
if (!this.ef) {
if(s.totalProperty) {
this.getTotal = this.getJsonAccessor(s.totalProperty);
}
if(s.successProperty) {
this.getSuccess = this.getJsonAccessor(s.successProperty);
}
this.getRoot = s.root ? this.getJsonAccessor(s.root) : function(p){return p;};
if (s.id) {
var g = this.getJsonAccessor(s.id);
this.getId = function(rec) {
var r = g(rec);
return (r === undefined || r === "") ? null : r;
};
} else {
this.getId = function(){return null;};
}
this.ef = [];
for(var i = 0; i < fl; i++){
f = fi[i];
var map = (f.mapping !== undefined && f.mapping !== null) ? f.mapping : f.name;
this.ef[i] = this.getJsonAccessor(map);
}
}
var root = this.getRoot(o), c = root.length, totalRecords = c, success = true;
if(s.totalProperty){
var v = parseInt(this.getTotal(o), 10);
if(!isNaN(v)){
totalRecords = v;
}
}
if(s.successProperty){
var v = this.getSuccess(o);
if(v === false || v === 'false'){
success = false;
}
}
var records = [];
for(var i = 0; i < c; i++){
var n = root[i];
var values = {};
var id = this.getId(n);
for(var j = 0; j < fl; j++){
f = fi[j];
var v = this.ef[j](n);
values[f.name] = f.convert((v !== undefined) ? v : f.defaultValue, n);
}
var record = new Record(values, id);
record.json = n;
records[i] = record;
}
return {
success : success,
records : records,
totalRecords : totalRecords
};
}
});