POST with rest kit - ios

Question

I have a JSON end path which accepts post requests in the following format.
{'values': [
{
"date":<measurement date as Unix time stamp>
"value":<weight>
}
{
"date":<measurement date as Unix time stamp>
"value":<weight>
}
...]}
"Values" is represented by the class "EntryCollection", while each value is represented by the class "Entry". I am puzzled finding the correct way to map my objects to the JSON representation. Right now I have the following code which causes the error: "The mapping operation was unable to find any nested object representations at the key paths searched".
RKObjectMapping *entryMapping = [RKObjectMapping requestMapping];
RKObjectMapping *valuesMapping = [RKObjectMapping mappingForClass:[EntriesCollection class]];
[valuesMapping addAttributeMappingsFromDictionary:[EntryCollection attributesMapping]];
[singleEntryMapping addAttributeMappingsFromDictionary:[SingleEntry attributesMapping]];
[singleEntryMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:#"entries" toKeyPath:#"entries" withMapping:valuesMapping]];
RKRequestDescriptor *requestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:entryMapping
objectClass:mappedClass
rootKeyPath:nil];
[self.objectManager addRequestDescriptor:requestDescriptor];
NSString *path = [self pathForPOST];
[self.objectManager postObject:weights path:path parameters:nil success:nil failure:nil];
EDIT for data structure
My data structure is simple (I suppose):
EntryCollection
- NSArray *entries (a collection of objects of type Entry)
Entry
- NSDate *date
- NSNumber *weight;
I would like to POST an EntryCollection filled with entries. The mapping of EntryCollection is "entries -> values", the one of Entry is "date -> date, weight -> value".

Answer 1

In any case, your JSON request payload must confirm to following data structure:
NSArray
|
|______NSDictionary ->Key: Date Value: weight
| ->Key: value Value: weight
|
|______NSDictionary ->Key: Date Value: weight
| ->Key: value Value: weight
|
|______NSDictionary ->Key: Date Value: weight
->Key: value Value: weight
Both NSArray and NSDictionary are fully compatible with JSON data format. I don't know about your underlying object structure, but ultimately this array should get posted as request payload NSData, and you will be done.

Answer 2

Well, if you have an issue in mapping, then you'll either have to show your model and class and mapping, or put RKLogConfigureByName("RestKit/ObjectMapping", RKLogLevelTrace); somewhere in your code and let us see output.
As an alternative, if your entities structure varies from what you want to Post to the server, you can use embedded AFNetworking client and do a simple request.
[[RKObjectManager sharedManager].HTTPClient postPath:#"" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(#"WHOOO");
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
//
}];

Answer 3

I have found the solution. Turns out, I needed a relationship mapping to describe the hierarchy implied in the JSON. Since there is no type for each entity of values, I created an "empty" mapping and added the relationship mapping to it.
I also forgot to set the correct MIMEType and inverse the attributes mapping of my class. I guess a few days in restkit are needed to get a grasp of it.
RKObjectMapping *entryMapping = [RKObjectMapping requestMapping];
[entryMapping addAttributeMappingsFromDictionary:[SingleEntry attributesMapping]];
RKObjectMapping *entrySerializedMapping = [entryMapping inverseMapping];
RKRelationshipMapping *entryRelationship = [RKRelationshipMapping relationshipMappingFromKeyPath:#"entries" toKeyPath:#"values" withMapping:entrySerializedMapping];
RKObjectMapping *valueMapping = [RKObjectMapping requestMapping];
[valueMapping addPropertyMapping:valueMapping];
RKRequestDescriptor *descriptor = [RKRequestDescriptor requestDescriptorWithMapping:valueMapping objectClass:[EntriesCollection class] rootKeyPath:nil];
[self.objectManager addRequestDescriptor:descriptor];
self.objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
NSString *path = [self pathForPOST];
[self.objectManager postObject:entryCollection path:path parameters:nil success:nil failure:nil];