itemfilewritestore.js

这是一个ajax的例子大家好好的看看就是一个鱼眼的效果

							}else{
								this._addReferenceToMap(possibleItem, item, attribute); 
							}
						}
					}, this);
					for(var rId in map){
						var removedItem;
						if(this._itemsByIdentity){
							removedItem = this._itemsByIdentity[rId];
						}else{
							removedItem = this._arrayOfAllItems[rId];
						}
						this._removeReferenceFromMap(removedItem, item, attribute);
					}
				}else{
					//Everything is new (no old values) so we have to just
					//insert all the references, if any.
					for(var i = 0; i < newValueArray.length; i++){
						var value = newValueArray[i];
						if(this.isItem(value)){
							this._addReferenceToMap(value, item, attribute);
						}
					}
				}
			}
			item[attribute] = newValueArray;
			success = true;
		}

		// Now we make the dojo.data.api.Notification call
		if(callOnSet){
			this.onSet(item, attribute, oldValueOrValues, newValueOrValues); 
		}
		return success; // boolean
	},

	_addReferenceToMap: function(/*item*/ refItem, /*item*/ parentItem, /*string*/ attribute){
		//	summary:
		//		Method to add an reference map entry for an item and attribute.
		//	description:
		//		Method to add an reference map entry for an item and attribute. 		 //
		//	refItem:
		//		The item that is referenced.
		//	parentItem:
		//		The item that holds the new reference to refItem.
		//	attribute:
		//		The attribute on parentItem that contains the new reference.
		 
		var parentId = this.getIdentity(parentItem);
		var references = refItem[this._reverseRefMap];

		if(!references){
			references = refItem[this._reverseRefMap] = {};
		}
		var itemRef = references[parentId];
		if(!itemRef){
			itemRef = references[parentId] = {};
		}
		itemRef[attribute] = true;
	},

	_removeReferenceFromMap: function(/* item */ refItem, /* item */ parentItem, /*strin*/ attribute){
		//	summary:
		//		Method to remove an reference map entry for an item and attribute.
		//	description:
		//		Method to remove an reference map entry for an item and attribute.  This will
		//		also perform cleanup on the map such that if there are no more references at all to 
		//		the item, its reference object and entry are removed.
		//
		//	refItem:
		//		The item that is referenced.
		//	parentItem:
		//		The item holding a reference to refItem.
		//	attribute:
		//		The attribute on parentItem that contains the reference.
		var identity = this.getIdentity(parentItem);
		var references = refItem[this._reverseRefMap];
		var itemId;
		if(references){
			for(itemId in references){
				if(itemId == identity){
					delete references[itemId][attribute];
					if(this._isEmpty(references[itemId])){
						delete references[itemId];
					}
				}
			}
			if(this._isEmpty(references)){
				delete refItem[this._reverseRefMap];
			}
		}
	},

	_dumpReferenceMap: function(){
		//	summary:
		//		Function to dump the reverse reference map of all items in the store for debug purposes.
		//	description:
		//		Function to dump the reverse reference map of all items in the store for debug purposes.
		var i;
		for(i = 0; i < this._arrayOfAllItems.length; i++){
			var item = this._arrayOfAllItems[i];
			if(item && item[this._reverseRefMap]){
				console.log("Item: [" + this.getIdentity(item) + "] is referenced by: " + dojo.toJson(item[this._reverseRefMap]));
			}
		}
	},
						   
	_getValueOrValues: function(/* item */ item, /* attribute-name-string */ attribute){
		var valueOrValues = undefined;
		if(this.hasAttribute(item, attribute)){
			var valueArray = this.getValues(item, attribute);
			if(valueArray.length == 1){
				valueOrValues = valueArray[0];
			}else{
				valueOrValues = valueArray;
			}
		}
		return valueOrValues;
	},
	
	_flatten: function(/* anything */ value){
		if(this.isItem(value)){
			var item = value;
			// Given an item, return an serializable object that provides a 
			// reference to the item.
			// For example, given kermit:
			//    var kermit = store.newItem({id:2, name:"Kermit"});
			// we want to return
			//    {_reference:2}
			var identity = this.getIdentity(item);
			var referenceObject = {_reference: identity};
			return referenceObject;
		}else{
			if(typeof value === "object"){
				for(var type in this._datatypeMap){
					var typeMap = this._datatypeMap[type];
					if (dojo.isObject(typeMap) && !dojo.isFunction(typeMap)){
						if(value instanceof typeMap.type){
							if(!typeMap.serialize){
								throw new Error("ItemFileWriteStore:  No serializer defined for type mapping: [" + type + "]");
							}
							return {_type: type, _value: typeMap.serialize(value)};
						}
					} else if(value instanceof typeMap){
						//SImple mapping, therefore, return as a toString serialization.
						return {_type: type, _value: value.toString()};
					}
				}
			}
			return value;
		}
	},
	
	_getNewFileContentString: function(){
		// summary: 
		//		Generate a string that can be saved to a file.
		//		The result should look similar to:
		//		http://trac.dojotoolkit.org/browser/dojo/trunk/tests/data/countries.json
		var serializableStructure = {};
		
		var identifierAttribute = this._getIdentifierAttribute();
		if(identifierAttribute !== Number){
			serializableStructure.identifier = identifierAttribute;
		}
		if(this._labelAttr){
			serializableStructure.label = this._labelAttr;
		}
		serializableStructure.items = [];
		for(var i = 0; i < this._arrayOfAllItems.length; ++i){
			var item = this._arrayOfAllItems[i];
			if(item !== null){
				var serializableItem = {};
				for(var key in item){
					if(key !== this._storeRefPropName && key !== this._itemNumPropName){
						var attribute = key;
						var valueArray = this.getValues(item, attribute);
						if(valueArray.length == 1){
							serializableItem[attribute] = this._flatten(valueArray[0]);
						}else{
							var serializableArray = [];
							for(var j = 0; j < valueArray.length; ++j){
								serializableArray.push(this._flatten(valueArray[j]));
								serializableItem[attribute] = serializableArray;
							}
						}
					}
				}
				serializableStructure.items.push(serializableItem);
			}
		}
		var prettyPrint = true;
		return dojo.toJson(serializableStructure, prettyPrint);
	},

	_isEmpty: function(something){
		//	summary: 
		//		Function to determine if an array or object has no properties or values.
		//	something:
		//		The array or object to examine.
		var empty = true;
		if(dojo.isObject(something)){
			var i;
			for(i in something){
				empty = false;
				break;
			}
		}else if(dojo.isArray(something)){
			if(something.length > 0){
				empty = false;
			}
		}
		return empty; //boolean
	},
	
	save: function(/* object */ keywordArgs){
		// summary: See dojo.data.api.Write.save()
		this._assert(!this._saveInProgress);
		
		// this._saveInProgress is set to true, briefly, from when save is first called to when it completes
		this._saveInProgress = true;
		
		var self = this;
		var saveCompleteCallback = function(){
			self._pending = {
				_newItems:{}, 
				_modifiedItems:{},
				_deletedItems:{}
			};

			self._saveInProgress = false; // must come after this._pending is cleared, but before any callbacks
			if(keywordArgs && keywordArgs.onComplete){
				var scope = keywordArgs.scope || dojo.global;
				keywordArgs.onComplete.call(scope);
			}
		};
		var saveFailedCallback = function(){
			self._saveInProgress = false;
			if(keywordArgs && keywordArgs.onError){
				var scope = keywordArgs.scope || dojo.global;
				keywordArgs.onError.call(scope);
			}
		};
		
		if(this._saveEverything){
			var newFileContentString = this._getNewFileContentString();
			this._saveEverything(saveCompleteCallback, saveFailedCallback, newFileContentString);
		}
		if(this._saveCustom){
			this._saveCustom(saveCompleteCallback, saveFailedCallback);
		}
		if(!this._saveEverything && !this._saveCustom){
			// Looks like there is no user-defined save-handler function.
			// That's fine, it just means the datastore is acting as a "mock-write"
			// store -- changes get saved in memory but don't get saved to disk.
			saveCompleteCallback();
		}
	},
	
	revert: function(){
		// summary: See dojo.data.api.Write.revert()
		this._assert(!this._saveInProgress);

		var identity;
		for(identity in this._pending._newItems){
			var newItem = this._pending._newItems[identity];
			newItem[this._storeRefPropName] = null;
			// null out the new item, but don't change the array index so
			// so we can keep using _arrayOfAllItems.length.
			this._arrayOfAllItems[newItem[this._itemNumPropName]] = null;
			if(newItem[this._rootItemPropName]){
				this._removeArrayElement(this._arrayOfTopLevelItems, newItem);
			}
			if(this._itemsByIdentity){
				delete this._itemsByIdentity[identity];
			}
		}
		for(identity in this._pending._modifiedItems){
			// find the original item and the modified item that replaced it
			var originalItem = this._pending._modifiedItems[identity];
			var modifiedItem = null;
			if(this._itemsByIdentity){
				modifiedItem = this._itemsByIdentity[identity];
			}else{
				modifiedItem = this._arrayOfAllItems[identity];
			}
			
			// make the original item into a full-fledged item again
			originalItem[this._storeRefPropName] = this;
			modifiedItem[this._storeRefPropName] = null;

			// replace the modified item with the original one
			var arrayIndex = modifiedItem[this._itemNumPropName];
			this._arrayOfAllItems[arrayIndex] = originalItem;
			
			if(modifiedItem[this._rootItemPropName]){
				var i;
				for (i = 0; i < this._arrayOfTopLevelItems.length; i++) {
					var possibleMatch = this._arrayOfTopLevelItems[i];
					if (this.getIdentity(possibleMatch) == identity){
						this._arrayOfTopLevelItems[i] = originalItem;
						break;
					}
				}
			}
			if(this._itemsByIdentity){
				this._itemsByIdentity[identity] = originalItem;
			}			
		}
		var deletedItem;
		for(identity in this._pending._deletedItems){
			deletedItem = this._pending._deletedItems[identity];
			deletedItem[this._storeRefPropName] = this;
			var index = deletedItem[this._itemNumPropName];

			//Restore the reverse refererence map, if any.
			if(deletedItem["backup_" + this._reverseRefMap]){
				deletedItem[this._reverseRefMap] = deletedItem["backup_" + this._reverseRefMap];
				delete deletedItem["backup_" + this._reverseRefMap];
			}
			this._arrayOfAllItems[index] = deletedItem;
			if (this._itemsByIdentity) {
				this._itemsByIdentity[identity] = deletedItem;
			}
			if(deletedItem[this._rootItemPropName]){
				this._arrayOfTopLevelItems.push(deletedItem);
			}	  
		}
		//We have to pass through it again and restore the reference maps after all the
		//undeletes have occurred.
		for(identity in this._pending._deletedItems){
			deletedItem = this._pending._deletedItems[identity];
			if(deletedItem["backupRefs_" + this._reverseRefMap]){
				dojo.forEach(deletedItem["backupRefs_" + this._reverseRefMap], function(reference){
					var refItem;
					if(this._itemsByIdentity){
						refItem = this._itemsByIdentity[reference.id];
					}else{
						refItem = this._arrayOfAllItems[reference.id];
					}
					this._addReferenceToMap(refItem, deletedItem, reference.attr);
				}, this);
				delete deletedItem["backupRefs_" + this._reverseRefMap]; 
			}
		}

		this._pending = {
			_newItems:{}, 
			_modifiedItems:{}, 
			_deletedItems:{}
		};
		return true; // boolean
	},
	
	isDirty: function(/* item? */ item){
		// summary: See dojo.data.api.Write.isDirty()
		if(item){
			// return true if the item is dirty
			var identity = this.getIdentity(item);
			return new Boolean(this._pending._newItems[identity] || 
				this._pending._modifiedItems[identity] ||
				this._pending._deletedItems[identity]); // boolean
		}else{
			// return true if the store is dirty -- which means return true
			// if there are any new items, dirty items, or modified items
			if(!this._isEmpty(this._pending._newItems) || 
			   !this._isEmpty(this._pending._modifiedItems) ||
			   !this._isEmpty(this._pending._deletedItems)){
				return true;
			}
			return false; // boolean
		}
	},

/* dojo.data.api.Notification */

	onSet: function(/* item */ item, 
					/*attribute-name-string*/ attribute, 
					/*object | array*/ oldValue,
					/*object | array*/ newValue){
		// summary: See dojo.data.api.Notification.onSet()
		
		// No need to do anything. This method is here just so that the 
		// client code can connect observers to it.
	},

	onNew: function(/* item */ newItem, /*object?*/ parentInfo){
		// summary: See dojo.data.api.Notification.onNew()
		
		// No need to do anything. This method is here just so that the 
		// client code can connect observers to it. 
	},

	onDelete: function(/* item */ deletedItem){
		// summary: See dojo.data.api.Notification.onDelete()
		
		// No need to do anything. This method is here just so that the 
		// client code can connect observers to it. 
	}
});

}