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// Copyright 2006 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview
* DataSource implementation that uses XMLHttpRequest as transport, with
* response as valid JSON.
*
* Response can have unexecutable starting/ending text to prevent inclusion
* using <script src="...">
*
*/
goog.provide('goog.ds.JsXmlHttpDataSource');
goog.require('goog.Uri');
goog.require('goog.ds.DataManager');
goog.require('goog.ds.FastDataNode');
goog.require('goog.ds.LoadState');
goog.require('goog.ds.logger');
goog.require('goog.events');
goog.require('goog.log');
goog.require('goog.net.EventType');
goog.require('goog.net.XhrIo');
/**
* Similar to JsonDataSource, with using XMLHttpRequest for transport
* Currently requires the result be a valid JSON.
*
* @param {(string|goog.Uri)} uri URI for the request.
* @param {string} name Name of the datasource.
* @param {string=} opt_startText Text to expect/strip before JS response.
* @param {string=} opt_endText Text to expect/strip after JS response.
* @param {boolean=} opt_usePost If true, use POST. Defaults to false (GET).
*
* @extends {goog.ds.FastDataNode}
* @constructor
* @final
*/
goog.ds.JsXmlHttpDataSource = function(
uri, name, opt_startText, opt_endText, opt_usePost) {
goog.ds.FastDataNode.call(this, {}, name, null);
if (uri) {
this.uri_ = new goog.Uri(uri);
this.xhr_ = new goog.net.XhrIo();
this.usePost_ = !!opt_usePost;
goog.events.listen(
this.xhr_, goog.net.EventType.COMPLETE, this.completed_, false, this);
} else {
this.uri_ = null;
}
this.startText_ = opt_startText;
this.endText_ = opt_endText;
};
goog.inherits(goog.ds.JsXmlHttpDataSource, goog.ds.FastDataNode);
/**
* Delimiter for start of JSON data in response.
* null = starts at first character of response
* @type {string|undefined}
* @private
*/
goog.ds.JsXmlHttpDataSource.prototype.startText_;
/**
* Delimiter for end of JSON data in response.
* null = ends at last character of response
* @type {string|undefined}
* @private
*/
goog.ds.JsXmlHttpDataSource.prototype.endText_;
/**
* Gets the state of the backing data for this node
* @return {goog.ds.LoadState} The state.
* @override
*/
goog.ds.JsXmlHttpDataSource.prototype.getLoadState = function() {
return this.loadState_;
};
/**
* Sets the request data. This can be used if it is required to
* send a specific body rather than build the body from the query
* parameters. Only used in POST requests.
* @param {string} data The data to send in the request body.
*/
goog.ds.JsXmlHttpDataSource.prototype.setQueryData = function(data) {
this.queryData_ = data;
};
/**
* Load or reload the backing data for this node.
* Fires the JsonDataSource
* @override
*/
goog.ds.JsXmlHttpDataSource.prototype.load = function() {
goog.log.info(
goog.ds.logger, 'Sending JS request for DataSource ' +
this.getDataName() + ' to ' + this.uri_);
if (this.uri_) {
if (this.usePost_) {
var queryData;
if (!this.queryData_) {
queryData = this.uri_.getQueryData().toString();
} else {
queryData = this.queryData_;
}
var uriNoQuery = this.uri_.clone();
uriNoQuery.setQueryData(null);
this.xhr_.send(String(uriNoQuery), 'POST', queryData);
} else {
this.xhr_.send(String(this.uri_));
}
} else {
this.loadState_ = goog.ds.LoadState.NOT_LOADED;
}
};
/**
* Called on successful request.
* @private
*/
goog.ds.JsXmlHttpDataSource.prototype.success_ = function() {
goog.ds.DataManager.getInstance().fireDataChange(this.getDataName());
};
/**
* Completed callback. Loads data if successful, otherwise sets
* state to FAILED
* @param {goog.events.Event} e Event object, Xhr is target.
* @private
*/
goog.ds.JsXmlHttpDataSource.prototype.completed_ = function(e) {
if (this.xhr_.isSuccess()) {
goog.log.info(
goog.ds.logger, 'Got data for DataSource ' + this.getDataName());
var text = this.xhr_.getResponseText();
// Look for start and end token and trim text
if (this.startText_) {
var startpos = text.indexOf(this.startText_);
text = text.substring(startpos + this.startText_.length);
}
if (this.endText_) {
var endpos = text.lastIndexOf(this.endText_);
text = text.substring(0, endpos);
}
// Parse result.
try {
var jsonObj = /** @type {!Object} */ (JSON.parse(text));
this.extendWith(jsonObj);
this.loadState_ = goog.ds.LoadState.LOADED;
} catch (ex) {
// Invalid JSON.
this.loadState_ = goog.ds.LoadState.FAILED;
goog.log.error(goog.ds.logger, 'Failed to parse data: ' + ex.message);
}
// Call on a timer to avoid threading issues on IE.
goog.global.setTimeout(goog.bind(this.success_, this), 0);
} else {
goog.log.info(
goog.ds.logger,
'Data retrieve failed for DataSource ' + this.getDataName());
this.loadState_ = goog.ds.LoadState.FAILED;
}
};
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