Request.js

define([
	'dojo/request',
	'dojo/_base/lang',
	'dojo/_base/array',
	'dojo/json',
	'dojo/_base/declare',
	'./Store',
	'./QueryResults'
], function (request, lang, arrayUtil, JSON, declare, Store, QueryResults) {

	var push = [].push;

	return declare(Store, {
		// summary:
		//		This is a basic store for RESTful communicating with a server through JSON
		//		formatted data. It extends dstore/Store.

		constructor: function () {
			// summary:
			//		This is a basic store for RESTful communicating with a server through JSON
			//		formatted data.
			// options: dstore/JsonRest
			//		This provides any configuration information that will be mixed into the store
			this.headers || (this.headers = {});

			this._targetContainsQueryString = this.target.lastIndexOf('?') >= 0;
		},

		// headers: Object
		//		Additional headers to pass in all requests to the server. These can be overridden
		//		by passing additional headers to calls to the store.
		headers: {},

		// parse: Function
		//		This function performs the parsing of the response text from the server. This
		//		defaults to JSON, but other formats can be parsed by providing an alternate
		//		parsing function. If you do want to use an alternate format, you will probably
		//		want to use an alternate stringify function for the serialization of data as well.
		//		Also, if you want to support parsing a larger set of JavaScript objects
		//		outside of strict JSON parsing, you can provide dojo/_base/json.fromJson as the parse function
		parse: JSON.parse,

		// target: String
		//		The target base URL to use for all requests to the server. This string will be
		//		prepended to the id to generate the URL (relative or absolute) for requests
		//		sent to the server
		target: '',

		// _targetContainsQueryString: Boolean
		//		A flag indicating whether the target contains a query string

		// sortParam: String
		//		The query parameter to used for holding sort information. If this is omitted, than
		//		the sort information is included in a functional query token to avoid colliding
		//		with the set of name/value pairs.

		// ascendingPrefix: String
		//		The prefix to apply to sort property names that are ascending
		ascendingPrefix: '+',

		// descendingPrefix: String
		//		The prefix to apply to sort property names that are ascending
		descendingPrefix: '-',

		// accepts: String
		//		Defines the Accept header to use on HTTP requests
		accepts: 'application/json',

		// useRangeHeaders: Boolean
		//		The indicates if range limits (start and end) should be specified
		//		a Range header, using items units. If this is set to true, a header
		//		be included of the form:
		//			Range: items=start-end

		// rangeStartParam: String
		//		The indicates if range limits (start and end) should be specified
		//		in a query parameter, and what the start parameter should be.
		//		This must be used in conjunction with the rangeCountParam
		//		If this is not specified, the range will
		//		included with a RQL style limit() parameter
		// rangeCountParam: String
		//		The indicates if range limits (start and end) should be specified
		//		in a query parameter, and what the count parameter should be.
		//		This must be used in conjunction with the rangeStartParam
		//		If this is not specified, the range will
		//		included with a RQL style limit() parameter

		fetch: function (kwArgs) {
			var results = this._request(kwArgs);
			return new QueryResults(results.data, {
				response: results.response
			});
		},

		fetchRange: function (kwArgs) {
			var start = kwArgs.start,
				end = kwArgs.end,
				requestArgs = {};
			if (this.useRangeHeaders) {
				requestArgs.headers = lang.mixin(this._renderRangeHeaders(start, end), kwArgs.headers);
			} else {
				requestArgs.queryParams = this._renderRangeParams(start, end);
				if (kwArgs.headers) {
					requestArgs.headers = kwArgs.headers;
				}
			}

			var results = this._request(requestArgs);
			return new QueryResults(results.data, {
				totalLength: results.total,
				response: results.response
			});
		},

		_request: function (kwArgs) {
			kwArgs = kwArgs || {};

			// perform the actual query
			var headers = lang.delegate(this.headers, { Accept: this.accepts });

			if ('headers' in kwArgs) {
				lang.mixin(headers, kwArgs.headers);
			}

			var requestUrl = this._renderUrl(kwArgs.queryParams);

			var response = request(requestUrl, {
				method: 'GET',
				headers: headers
			});
			var collection = this;
			var parsedResponse = response.then(function (response) {
				return collection.parse(response);
			});
			return {
				data: parsedResponse.then(function (data) {
					// support items in the results
					var results = data.items || data;
					for (var i = 0, l = results.length; i < l; i++) {
						results[i] = collection._restore(results[i], true);
					}
					return results;
				}),
				total: parsedResponse.then(function (data) {
					// check for a total property
					var total = data.total;
					if (total > -1) {
						// if we have a valid positive number from the data,
						// we can use that
						return total;
					}
					// else use headers
					return response.response.then(function (response) {
						var range = response.getHeader('Content-Range');
						return range && (range = range.match(/\/(.*)/)) && +range[1];
					});
				}),
				response: response.response
			};
		},

		_renderFilterParams: function (filter) {
			// summary:
			//		Constructs filter-related params to be inserted into the query string
			// returns: String
			//		Filter-related params to be inserted in the query string
			var type = filter.type;
			var args = filter.args;
			if (!type) {
				return [''];
			}
			if (type === 'string') {
				return [args[0]];
			}
			if (type === 'and' || type === 'or') {
				return [arrayUtil.map(filter.args, function (arg) {
					// render each of the arguments to and or or, then combine by the right operator
					var renderedArg = this._renderFilterParams(arg);
					return ((arg.type === 'and' || arg.type === 'or') && arg.type !== type) ?
						// need to observe precedence in the case of changing combination operators
						'(' + renderedArg + ')' : renderedArg;
				}, this).join(type === 'and' ? '&' : '|')];
			}
			var target = args[1];
			if (target) {
				if(target._renderUrl) {
					// detected nested query, and render the url inside as an argument
					target = '(' + target._renderUrl() + ')';
				} else if (target instanceof Array) {
					target = '(' + target + ')';
				}
			}
			return [encodeURIComponent(args[0]) + '=' + (type === 'eq' ? '' : type + '=') + encodeURIComponent(target)];
		},
		_renderSortParams: function (sort) {
			// summary:
			//		Constructs sort-related params to be inserted in the query string
			// returns: String
			//		Sort-related params to be inserted in the query string

			var sortString = arrayUtil.map(sort, function (sortOption) {
				var prefix = sortOption.descending ? this.descendingPrefix : this.ascendingPrefix;
				return prefix + encodeURIComponent(sortOption.property);
			}, this);

			var params = [];
			if (sortString) {
				params.push(this.sortParam
					? encodeURIComponent(this.sortParam) + '=' + sortString
					: 'sort(' + sortString + ')'
				);
			}
			return params;
		},
		_renderRangeParams: function (start, end) {
			// summary:
			//		Constructs range-related params to be inserted in the query string
			// returns: String
			//		Range-related params to be inserted in the query string
			var params = [];
			if (this.rangeStartParam) {
				params.push(
					this.rangeStartParam + '=' + start,
					this.rangeCountParam + '=' + (end - start)
				);
			} else {
				params.push('limit(' + (end - start) + (start ? (',' + start) : '') + ')');
			}
			return params;
		},

		_renderSelectParams: function (properties) {
			// summary:
			//		Constructs range-related params to be inserted in the query string
			// returns: String
			//		Range-related params to be inserted in the query string
			var params = [];
			if (this.selectParam) {
				params.push(this.selectParam + '=' + properties);
			} else {
				params.push('select(' + properties + ')');
			}
			return params;
		},

		_renderQueryParams: function () {
			var queryParams = [];

			arrayUtil.forEach(this.queryLog, function (entry) {
				var type = entry.type,
					renderMethod = '_render' + type[0].toUpperCase() + type.substr(1) + 'Params';

				if (this[renderMethod]) {
					push.apply(queryParams, this[renderMethod].apply(this, entry.normalizedArguments));
				} else {
					console.warn('Unable to render query params for "' + type + '" query', entry);
				}
			}, this);

			return queryParams;
		},

		_renderUrl: function (requestParams) {
			// summary:
			//		Constructs the URL used to fetch the data.
			// returns: String
			//		The URL of the data

			var queryParams = this._renderQueryParams(),
				requestUrl = this.target;

			if (requestParams) {
				push.apply(queryParams, requestParams);
			}

			if (queryParams.length > 0) {
				requestUrl += (this._targetContainsQueryString ? '&' : '?') + queryParams.join('&');
			}
			return requestUrl;
		},

		_renderRangeHeaders: function (start, end) {
			// summary:
			//		Applies a Range header if this collection incorporates a range query
			// headers: Object
			//		The headers to which a Range property is added

			var value = 'items=' + start + '-' + (end - 1);
			return {
				'Range': value,
				'X-Range': value //set X-Range for Opera since it blocks "Range" header
			};
		}
	});

});