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

[Douglas Campos]

Ah so the mapping is reversed then?

On 04/01/2013, at 11:16, Matthias Wessendorf <matzew at apache.org> wrote:

> 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
> > _______________________________________________
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> > 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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