bigfish24 / RealmSubqueryHelper

RLMObject category to simplify performing a query containing a subquery on link objects

RealmSubqueryHelper

#####Adds support for SUBQUERY in Realm queries.

Need to query a RLMObject against a to-many relationship using multiple properties? This category brings the hidden gem in NSPredicate, SUBQUERY, to Realm. For example, given this Realm setup:

Person : RLMObject
@property NSString *Id;
@property RLMArray<Dog> *dogs;

Dog : RLMObject
@property BOOL hasFleas;
@property NSString *color;

it is now possible to write a query for all the Person(s) that have at least one Dog with fleas and is colored brown. This makes use of SUBQUERY in the resulting Realm query:

RLMResults *ownersOfBrownDogsWithFleas = [Person objectsWithSubqueryPredicate:@"SUBQUERY(dogs, $dog, $dog.hasFleas = YES AND $dog.color == 'brown').@count > 0"];

####Format The format is similar to the standard NSPredicate SUBQUERY expression:

SUBQUERY(RLMArray keypath, variable, predicate)

####Installation RBQFetchedResultsController is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'RealmSubqueryHelper'

####Demo

Build and run/test the Example project in Xcode to see a working SUBQUERY. This project uses CocoaPods. If you don't have CocoaPods installed, grab it with [sudo] gem install cocoapods.

git clone https://github.com/bigfish24/RealmSubqueryHelper
cd RealmSubqueryHelper/objc-example
pod install
open RBQFetchedResultsControllerExample.xcworkspace

#####Requirements

• iOS 7+

####Limitations

1. The base object must have a primary key (above, Person has primary key Id).
2. Only the @count collection operator is supported.
3. Compound predicates with SUBQUERY are supported, but nested SUBQUERY is not.