How to serialize NSManagedObject to JSON in restkit 0.20?
How to serialize NSManagedObject to JSON in restkit 0.20 using reverse mapping?
I don't need to post anything now.
I would like to manually create a MyObjectManaged object. Set some attributes, for example: I would, name, age
Match them to my existing mapping to JSON attributes: User id, name, age
create and print JSON.
Is it possible? When, yes, how? Thank you in advance for your reply.
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I recently tried to do the same :) I wanted to keep the mappings so that I can eventually connect to the server, but also reuse them to serialize objects to a file.
I did it using inverseMapping and executing it via RKMappingOperation.
First set up your mappings from JSON -> Core Data Object
RKEntityMapping mapping = [RKEntityMapping mappingForEntityForName:@"MyManagedObject" inManagedObjectStore:rkManagedObjectStore];
[self.nodeMapping addAttributeMappingsFromDictionary:@{
@"userid": @"id",
@"first_name": @"name",
@"age": @"age"
}];
Then use reverse mapping to map an object instance (such as "myObject") to a dictionary:
NSMutableDictionary *jsonDict = [NSMutableDictionary dictionary];
RKObjectMappingOperationDataSource *dataSource = [RKObjectMappingOperationDataSource new];
RKMappingOperation *operation = [[RKMappingOperation alloc] initWithSourceObject:myObject
destinationObject:jsonDict
mapping:[mapping inverseMapping]];
operation.dataSource = dataSource;
NSError *error = nil;
[operation performMapping:&error];
Assuming there is no error, you can serialize the dictionary:
NSData *data = [RKMIMETypeSerialization dataFromObject:jsonDict
MIMEType:RKMIMETypeJSON
error:&error];
Not sure what you wanted to do with it, but if you wanted to print it to a string you could do:
NSString *jsonString = [[NSString alloc] initWithData:data
encoding:NSUTF8StringEncoding]
Hope it helps
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John Martin's answer seems to work, but I'm having a problem with NSManagedObject instances with NSNumber property set using
[NSNumber numberWithBool:boolvalue]
serializes json value as 1/0 instead of true / false. Our backend couldn't handle numbers as booleans.
I solved it with built-in RestKit class: RKObjectParameterization
Using the following method, my NSManagedObjects were serialized correctly when the NSNumber property existed and was set to bool.
+ (NSString *)getJsonObjectWithDescriptor:(RKRequestDescriptor *)requestDescriptor objectToParse:(id)objectToParse {
NSError *error = nil;
NSDictionary *jsonDict = [RKObjectParameterization parametersWithObject:objectToParse requestDescriptor:requestDescriptor error:&error];
NSData *data = [RKMIMETypeSerialization dataFromObject:jsonDict
MIMEType:RKMIMETypeJSON
error:&error];
return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
}
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You can go to the RestKit wiki and look into object mapping . See the section on Object Parameterization and Serialization for information on serialization and reverse mapping.
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