JsonRest.js

define("dojox/rpc/JsonRest", ["dojo", "dojox", "dojox/json/ref", "dojox/rpc/Rest"], function(dojo, dojox) {
	var dirtyObjects = [];
	var Rest = dojox.rpc.Rest;
	var jr;
	function resolveJson(service, deferred, value, defaultId){
		var timeStamp = deferred.ioArgs && deferred.ioArgs.xhr && deferred.ioArgs.xhr.getResponseHeader("Last-Modified");
		if(timeStamp && Rest._timeStamps){
			Rest._timeStamps[defaultId] = timeStamp;
		}
		var hrefProperty = service._schema && service._schema.hrefProperty;
		if(hrefProperty){
			dojox.json.ref.refAttribute = hrefProperty;
		}
		value = value && dojox.json.ref.resolveJson(value, {
			defaultId: defaultId,
			index: Rest._index,
			timeStamps: timeStamp && Rest._timeStamps,
			time: timeStamp,
			idPrefix: service.servicePath.replace(/[^\/]*$/,''),
			idAttribute: jr.getIdAttribute(service),
			schemas: jr.schemas,
			loader:	jr._loader,
			idAsRef: service.idAsRef,
			assignAbsoluteIds: true
		});
		dojox.json.ref.refAttribute  = "$ref";
		return value;
	}
	jr = dojox.rpc.JsonRest={
		serviceClass: dojox.rpc.Rest,
		conflictDateHeader: "If-Unmodified-Since",
		commit: function(kwArgs){
			// summary:
			//		Saves the dirty data using REST Ajax methods

			kwArgs = kwArgs || {};
			var actions = [];
			var alreadyRecorded = {};
			var savingObjects = [];
			for(var i = 0; i < dirtyObjects.length; i++){
				var dirty = dirtyObjects[i];
				var object = dirty.object;
				var old = dirty.old;
				var append = false;
				if(!(kwArgs.service && (object || old) &&
						(object || old).__id.indexOf(kwArgs.service.servicePath)) && dirty.save){
					delete object.__isDirty;
					if(object){
						if(old){
							// changed object
							var pathParts;
							if((pathParts = object.__id.match(/(.*)#.*/))){ // it is a path reference
								// this means it is a sub object, we must go to the parent object and save it
								object = Rest._index[pathParts[1]];
							}
							if(!(object.__id in alreadyRecorded)){// if it has already been saved, we don't want to repeat it
								// record that we are saving
								alreadyRecorded[object.__id] = object;
								if(kwArgs.incrementalUpdates
									&& !pathParts){ // I haven't figured out how we would do incremental updates on sub-objects yet
									// make an incremental update using a POST
									var incremental = (typeof kwArgs.incrementalUpdates == 'function' ?
										kwArgs.incrementalUpdates : function(){
											incremental = {};
											for(var j in object){
												if(object.hasOwnProperty(j)){
													if(object[j] !== old[j]){
														incremental[j] = object[j];
													}
												}else if(old.hasOwnProperty(j)){
													// we can't use incremental updates to remove properties
													return null;
												}
											}
											return incremental;
										})(object, old);
								}
								
								if(incremental){
									actions.push({method:"post",target:object, content: incremental});
								}
								else{
									actions.push({method:"put",target:object,content:object});
								}
							}
						}else{
							// new object
							var service = jr.getServiceAndId(object.__id).service;
							var idAttribute = jr.getIdAttribute(service);
							if((idAttribute in object) && !kwArgs.alwaysPostNewItems){
								// if the id attribute is specified, then we should know the location
								actions.push({method:"put",target:object, content:object});
							}else{
								actions.push({method:"post",target:{__id:service.servicePath},
														content:object});
							}
						}
					}else if(old){
						// deleted object
						actions.push({method:"delete",target:old});
					}//else{ this would happen if an object is created and then deleted, don't do anything
					savingObjects.push(dirty);
					dirtyObjects.splice(i--,1);
				}
			}
			dojo.connect(kwArgs,"onError",function(){
				if(kwArgs.revertOnError !== false){
					var postCommitDirtyObjects = dirtyObjects;
					dirtyObjects = savingObjects;
					var numDirty = 0; // make sure this does't do anything if it is called again
					jr.revert(); // revert if there was an error
					dirtyObjects = postCommitDirtyObjects;
				}
				else{
					dojo.forEach(savingObjects, function(obj) {
						jr.changing(obj.object, !obj.object);
				    });
				}
			});
			jr.sendToServer(actions, kwArgs);
			return actions;
		},
		sendToServer: function(actions, kwArgs){
			var xhrSendId;
			var plainXhr = dojo.xhr;
			var left = actions.length;// this is how many changes are remaining to be received from the server
			var i, contentLocation;
			var timeStamp;
			var conflictDateHeader = this.conflictDateHeader;
			// add headers for extra information
			dojo.xhr = function(method,args){
				// keep the transaction open as we send requests
				args.headers = args.headers || {};
				// the last one should commit the transaction
				args.headers['Transaction'] = actions.length - 1 == i ? "commit" : "open";
				if(conflictDateHeader && timeStamp){
					args.headers[conflictDateHeader] = timeStamp;
				}
				if(contentLocation){
					args.headers['Content-ID'] = '<' + contentLocation + '>';
				}
				return plainXhr.apply(dojo,arguments);
			};
			for(i =0; i < actions.length;i++){ // iterate through the actions to execute
				var action = actions[i];
				dojox.rpc.JsonRest._contentId = action.content && action.content.__id; // this is used by OfflineRest
				var isPost = action.method == 'post';
				timeStamp = action.method == 'put' && Rest._timeStamps[action.content.__id];
				if(timeStamp){
					// update it now
					Rest._timeStamps[action.content.__id] = (new Date()) + '';
				}
				// send the content location to the server
				contentLocation = isPost && dojox.rpc.JsonRest._contentId;
				var serviceAndId = jr.getServiceAndId(action.target.__id);
				var service = serviceAndId.service;
				var dfd = action.deferred = service[action.method](
									serviceAndId.id.replace(/#/,''), // if we are using references, we need eliminate #
									dojox.json.ref.toJson(action.content, false, service.servicePath, true)
								);
				(function(object, dfd, service){
					dfd.addCallback(function(value){
						try{
							// Implements id assignment per the HTTP specification
							var newId = dfd.ioArgs.xhr && dfd.ioArgs.xhr.getResponseHeader("Location");
							//TODO: match URLs if the servicePath is relative...
							if(newId){
								// if the path starts in the middle of an absolute URL for Location, we will use the just the path part
								var startIndex = newId.match(/(^\w+:\/\/)/) && newId.indexOf(service.servicePath);
								newId = startIndex > 0 ? newId.substring(startIndex) : (service.servicePath + newId).
										// now do simple relative URL resolution in case of a relative URL.
										replace(/^(.*\/)?(\w+:\/\/)|[^\/\.]+\/\.\.\/|^.*\/(\/)/,'$2$3');
								object.__id = newId;
								Rest._index[newId] = object;
							}
							value = resolveJson(service, dfd, value, object && object.__id);
						}catch(e){}
						if(!(--left)){
							if(kwArgs.onComplete){
								kwArgs.onComplete.call(kwArgs.scope, actions);
							}
						}
						return value;
					});
				})(action.content, dfd, service);
								
				dfd.addErrback(function(value){
					
					// on an error we want to revert, first we want to separate any changes that were made since the commit
					left = -1; // first make sure that success isn't called
					kwArgs.onError.call(kwArgs.scope, value);
				});
			}
			// revert back to the normal XHR handler
			dojo.xhr = plainXhr;
			
		},
		getDirtyObjects: function(){
			return dirtyObjects;
		},
		revert: function(service){
			// summary:
			//		Reverts all the changes made to JSON/REST data
			for(var i = dirtyObjects.length; i > 0;){
				i--;
				var dirty = dirtyObjects[i];
				var object = dirty.object;
				var old = dirty.old;
				var store = dojox.data._getStoreForItem(object || old);
				
				if(!(service && (object || old) &&
					(object || old).__id.indexOf(service.servicePath))){
					// if we are in the specified store or if this is a global revert
					if(object && old){
						// changed
						for(var j in old){
							if(old.hasOwnProperty(j) && object[j] !== old[j]){
								if(store){
									store.onSet(object, j, object[j], old[j]);
								}
								object[j] = old[j];
							}
						}
						for(j in object){
							if(!old.hasOwnProperty(j)){
								if(store){
									store.onSet(object, j, object[j]);
								}
								delete object[j];
							}
						}
					}else if(!old){
						// was an addition, remove it
						if(store){
							store.onDelete(object);
						}
					}else{
						// was a deletion, we will add it back
						if(store){
							store.onNew(old);
						}
					}
					delete (object || old).__isDirty;
					dirtyObjects.splice(i, 1);
				}
			}
		},
		changing: function(object,_deleting){
			// summary:
			//		adds an object to the list of dirty objects.  This object
			//		contains a reference to the object itself as well as a
			//		cloned and trimmed version of old object for use with
			//		revert.
			if(!object.__id){
				return;
			}
			object.__isDirty = true;
			//if an object is already in the list of dirty objects, don't add it again
			//or it will overwrite the premodification data set.
			for(var i=0; i<dirtyObjects.length; i++){
				var dirty = dirtyObjects[i];
				if(object==dirty.object){
					if(_deleting){
						// we are deleting, no object is an indicator of deletiong
						dirty.object = false;
						if(!this._saveNotNeeded){
							dirty.save = true;
						}
					}
					return;
				}
			}
			var old = object instanceof Array ? [] : {};
			for(i in object){
				if(object.hasOwnProperty(i)){
					old[i] = object[i];
				}
			}
			dirtyObjects.push({object: !_deleting && object, old: old, save: !this._saveNotNeeded});
		},
		deleteObject: function(object){
			// summary:
			//		deletes an object
			// object:
			//		object to delete
			this.changing(object,true);
		},
		getConstructor: function(/*Function|String*/service, schema){
			// summary:
			//		Creates or gets a constructor for objects from this service
			if(typeof service == 'string'){
				var servicePath = service;
				service = new dojox.rpc.Rest(service,true);
				this.registerService(service, servicePath, schema);
			}
			if(service._constructor){
				return service._constructor;
			}
			service._constructor = function(data){
				// summary:
				//		creates a new object for this table
				// data:
				//		object to mixed in
				var self = this;
				var args = arguments;
				var properties;
				var initializeCalled;
				function addDefaults(schema){
					if(schema){
						addDefaults(schema['extends']);
						properties = schema.properties;
						for(var i in properties){
							var propDef = properties[i];
							if(propDef && (typeof propDef == 'object') && ("default" in propDef)){
								self[i] = propDef["default"];
							}
						}
					}
					if(schema && schema.prototype && schema.prototype.initialize){
						initializeCalled = true;
						schema.prototype.initialize.apply(self, args);
					}
				}
				addDefaults(service._schema);
				if(!initializeCalled && data && typeof data == 'object'){
					dojo.mixin(self,data);
				}
				var idAttribute = jr.getIdAttribute(service);
				Rest._index[this.__id = this.__clientId =
						service.servicePath + (this[idAttribute] ||
							Math.random().toString(16).substring(2,14) + '@' + ((dojox.rpc.Client && dojox.rpc.Client.clientId) || "client"))] = this;
				if(dojox.json.schema && properties){
					dojox.json.schema.mustBeValid(dojox.json.schema.validate(this, service._schema));
				}
				dirtyObjects.push({object:this, save: true});
			};
			return dojo.mixin(service._constructor, service._schema, {load:service});
		},
		fetch: function(absoluteId){
			// summary:
			//		Fetches a resource by an absolute path/id and returns a dojo.Deferred.
			var serviceAndId = jr.getServiceAndId(absoluteId);
			return this.byId(serviceAndId.service,serviceAndId.id);
		},
		getIdAttribute: function(service){
			// summary:
			//		Return the ids attribute used by this service (based on it's schema).
			//		Defaults to "id", if not other id is defined
			var schema = service._schema;
			var idAttr;
			if(schema){
				if(!(idAttr = schema._idAttr)){
					for(var i in schema.properties){
						if(schema.properties[i].identity || (schema.properties[i].link == "self")){
							schema._idAttr = idAttr = i;
						}
					}
				}
			}
			return idAttr || 'id';
		},
		getServiceAndId: function(/*String*/absoluteId){
			// summary:
			//		Returns the REST service and the local id for the given absolute id. The result
			//		is returned as an object with a service property and an id property
			// absoluteId:
			//		This is the absolute id of the object
			var serviceName = '';
			
			for(var service in jr.services){
				if((absoluteId.substring(0, service.length) == service) && (service.length >= serviceName.length)){
					serviceName = service;
				}
			}
			if (serviceName){
				return {service: jr.services[serviceName], id:absoluteId.substring(serviceName.length)};
			}
			var parts = absoluteId.match(/^(.*\/)([^\/]*)$/);
			return {service: new jr.serviceClass(parts[1], true), id:parts[2]};
		},
		services:{},
		schemas:{},
		registerService: function(/*Function*/ service, /*String*/ servicePath, /*Object?*/ schema){
			// summary:
			//		Registers a service for as a JsonRest service, mapping it to a path and schema
			// service:
			//		This is the service to register
			// servicePath:
			//		This is the path that is used for all the ids for the objects returned by service
			// schema:
			//		This is a JSON Schema object to associate with objects returned by this service
			servicePath = service.servicePath = servicePath || service.servicePath;
			service._schema = jr.schemas[servicePath] = schema || service._schema || {};
			jr.services[servicePath] = service;
		},
		byId: function(service, id){
			// if caching is allowed, we look in the cache for the result
			var deferred, result = Rest._index[(service.servicePath || '') + id];
			if(result && !result._loadObject){// cache hit
				deferred = new dojo.Deferred();
				deferred.callback(result);
				return deferred;
			}
			return this.query(service, id);
		},
		query: function(service, id, args){
			var deferred = service(id, args);
			
			deferred.addCallback(function(result){
				if(result.nodeType && result.cloneNode){
					// return immediately if it is an XML document
					return result;
				}
				return resolveJson(service, deferred, result, typeof id != 'string' || (args && (args.start || args.count)) ? undefined: id);
			});
			return deferred;
		},
		_loader: function(callback){
			// load a lazy object
			var serviceAndId = jr.getServiceAndId(this.__id);
			var self = this;
			jr.query(serviceAndId.service, serviceAndId.id).addBoth(function(result){
				// if they are the same this means an object was loaded, otherwise it
				// might be a primitive that was loaded or maybe an error
				if(result == self){
					// we can clear the flag, so it is a loaded object
					delete result.$ref;
					delete result._loadObject;
				}else{
					// it is probably a primitive value, we can't change the identity of an object to
					//	the loaded value, so we will keep it lazy, but define the lazy loader to always
					//	return the loaded value
					self._loadObject = function(callback){
						callback(result);
					};
				}
				callback(result);
			});
		},
		isDirty: function(item, store){
			// summary:
			//		returns true if the item is marked as dirty or true if there are any dirty items
			if(!item){
				if(store){
					return dojo.some(dirtyObjects, function(dirty){
						return dojox.data._getStoreForItem(dirty.object || dirty.old) == store;
					});
				}
				return !!dirtyObjects.length;
			}
			return item.__isDirty;
		}
		
	};

	return dojox.rpc.JsonRest;
});