JsonReader.js
/**
* @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.
* <p>
* The code below lists all configuration options.
* <pre><code>
var RecordDef = 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 number of returned records (可选)
root: "rows", // The property which contains an Array of record objects
id: "id" // The property within the record object that provides an ID for the record (可选)
}, RecordDef);
</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>
* @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[]/Ext.data.Record constructor} recordType The record definition of the data record to produce.
*/
Ext.data.JsonReader = function(meta, recordType){
Ext.data.JsonReader.superclass.constructor.call(this, meta, recordType);
};
Ext.extend(Ext.data.JsonReader, Ext.data.DataReader, {
/**
* 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"};
}
return this.readRecords(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 an XML document.
* @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.
* @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);
}
var record = new Record(values, id);
record.json = n;
records[i] = record;
}
return {
success : success,
records : records,
totalRecords : totalRecords
};
}
});
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