[aerogear-dev] iOS/CoreData - API proposal - AGEntityMapper

[Matthias Wessendorf]

There is some code in Mantle, which does that; my look up mechanism will
borrow that - but that's an impl detail

The mapper goal is really just to say JSON "key" 'blah' is mapped to 'foo'
on the actual bean (not about the specific types)

Makes sense?

-M


On Fri, Jan 4, 2013 at 2:09 PM, Douglas Campos <qmx at qmx.me> wrote:

> how the mapper deals with nested objects?
>
> On 04/01/2013, at 08:55, Matthias Wessendorf <matzew at apache.org> wrote:
>
> > CoreData: API proposal - AGEntityMapper
> > Background
> > Mapping JSON representations to a "rich" domain model in ObjC is a bit
> cumbersome. Similar is true when mapping a JSON data/response to a
> NSMangedObject (and vise versa). There is a base framework for "remote
> persistence", via the CoreData API, by leveraging a custom
> NSIncrementalStore -> AFIncrementalStore.
> >
> > For that,... a similar two-way-mapping is required, as described here.
> >
> > AeroGear and CoreData
> > Our CoreData offerings are leveraging the AFIncrementalStore, therefore
> (as with other frameworks/libraries) we need a mapping as well. We need to
> know the name of the entity and we need a NSDictionary that covers the
> actual JSON/property mapping. It could be done with the vanialla ObjC
> classes:
> >
> > // some mappers:
> > NSDictionary *task_mapper =
> >
> >
> > [NSDictionary dictionaryWithObjectsAndKeys:@"description",@"desc",@"id",@"myId",
> nil];
> > NSDictionary *project_mapper =
> >
> >
> > [NSDictionary dictionaryWithObjectsAndKeys:@"id",@"myId", nil];
> >
> >
> >
> > // create a schema out of the mappers:
> > NSDictionary *schema =
> >
> >
> > [NSDictionary dictionaryWithObjectsAndKeys:task_mapper, @"Task",
> project_mapper, @"Project", nil];
> >
> >
> >
> > // pass the schema to the AGCoreDataHelper class, when doing the init...
> > Proposal for a custom API
> > I'd like to introduce a new wrapper type, called AGEntityMapper:
> >
> > @interface AGEnityMapper : NSObject
> >
> >
> >
> > @property NSString *name;
> > @property NSDictionary *mapper;
> >
> >
> >
> > -(id) initWithName:(NSString *) name mapper:(NSDictionary *) mapper;
> > @end
> > This AGEntityMapper would be applied onto the AGCoreDataConfig:
> >
> > @protocol AGCoreDataConfig <NSObject>
> >
> >
> >
> > @property (strong, nonatomic) NSManagedObjectModel *managedObjectModel;
> > @property (strong, nonatomic) NSURL *baseURL;
> >
> >
> >
> > -(void)applyEntityMappers:(AGEnityMapper *)firstObject, ...
> NS_REQUIRES_NIL_TERMINATION;
> >
> >
> >
> > @end
> > The actual code, would look like this:
> >
> > EnityMapper *taskMapper =
> >
> >
> > [[EnityMapper alloc] initWithName:@"Task"
> >
> >
> > // mapping the properties on the "entity" (NSManagedObject)
> >
> >
> > // to the external representation (e.g. JSON)
> >
> >
> > mapper:@{ @"desc": @"description", @"myId": @"id"}];
> >
> >
> >
> > EnityMapper *projectMapper =
> >
> >
> > [[EnityMapper alloc] initWithName:@"Project"
> >
> >
> > // mapping the properties on the "entity" (NSManagedObject)
> >
> >
> > // to the external representation (e.g. JSON)
> >
> >
> > mapper:@{ @"myId": @"id"}];
> >
> >
> >
> > AGCoreDataHelper *helper = [[AGCoreDataHelper alloc]
> initWithConfig:^(id<AGCoreDataConfig> config) {
> >
> >
> >
> > [config setBaseURL:[NSURL URLWithString:@"http://server.com"]];
> >
> >
> >
> > [config applyEntityMappers:
> >
> >
> > taskMapper,
> >
> >
> > projectMapper,
> >
> >
> > nil // terminate the varargs.
> >
> >
> > ];
> > }];
> >
> > --
> > Matthias Wessendorf
> >
> > blog: http://matthiaswessendorf.wordpress.com/
> > sessions: http://www.slideshare.net/mwessendorf
> > twitter: http://twitter.com/mwessendorf
> > _______________________________________________
> > aerogear-dev mailing list
> > aerogear-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/aerogear-dev
>
>
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-- 
Matthias Wessendorf

blog: http://matthiaswessendorf.wordpress.com/
sessions: http://www.slideshare.net/mwessendorf
twitter: http://twitter.com/mwessendorf
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