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RestKit/Code/ObjectMapping/RKMappingOperationDataSource.h

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Objective-C

//
// RKMappingOperationDataSource.h
// RestKit
//
// Created by Blake Watters on 7/3/12.
// Copyright (c) 2012 RestKit. 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.
//
#import <Foundation/Foundation.h>
@class RKObjectMapping, RKMappingOperation, RKRelationshipMapping;
/**
An object that adopts the `RKMappingOperationDataSource` protocol is responsible for the retrieval or creation of target objects within an `RKMapperOperation` or `RKMappingOperation`. A data source is responsible for meeting the requirements of the underlying data store implementation and must return a key-value coding compliant object instance that can be used as the target object of a mapping operation. It is also responsible for commiting any changes necessary to the underlying data store once a mapping operation has completed its work.
At a minimum, a data source must implement the `mappingOperation:targetObjectForRepresentation:withMapping:` method. This method is responsible for finding an existing object instance to be updated or creating a new object if no existing object could be found or the underlying data store does not support persistence. Object mapping operations which target `NSObject` derived classes will always result in mapping to new transient objects, while persistent data stores such as Core Data can be queried to retrieve existing objects for update.
@see `RKManagedObjectMappingOperationDataSource`
*/
@protocol RKMappingOperationDataSource <NSObject>
@required
/**
Asks the data source for the target object for an object mapping operation given an `NSDictionary` representation of the object's properties and the mapping object that will be used to perform the mapping.
The `representation` value is a fragment of content from a deserialized response that has been identified as containing content that is mappable using the given mapping.
@param mappingOperation The mapping operation requesting the target object.
@param representation A dictionary representation of the properties to be mapped onto the retrieved target object.
@param mapping The object mapping to be used to perform a mapping from the representation to the target object.
@return A key-value coding compliant object to perform the mapping on to.
*/
- (id)mappingOperation:(RKMappingOperation *)mappingOperation targetObjectForRepresentation:(NSDictionary *)representation withMapping:(RKObjectMapping *)mapping inRelationship:(RKRelationshipMapping *)relationshipMapping;
@optional
/**
Tells the data source to commit any changes to the underlying data store.
@param mappingOperation The mapping operation that has completed its work.
@param error A pointer to an error to be set in the event that the mapping operation could not be committed.
@return A Boolean value indicating if the changes for the mapping operation were committed successfully.
*/
- (BOOL)commitChangesForMappingOperation:(RKMappingOperation *)mappingOperation error:(NSError **)error;
/**
Tells the data source to delete the existing value for a relationship that has been mapped with an assignment policy of `RKReplaceAssignmentPolicy`.
@param mappingOperation The mapping operation that is executing.
@param relationshipMapping The relationship mapping for which the existing value is being replaced.
@param error A pointer to an error to be set in the event that the deletion operation could not be completed.
@return A Boolean value indicating if the existing objects for the relationship were successfully deleted.
*/
- (BOOL)mappingOperation:(RKMappingOperation *)mappingOperation deleteExistingValueOfRelationshipWithMapping:(RKRelationshipMapping *)relationshipMapping error:(NSError **)error;
@end