Relationship

  • This class allows for various customizations to the YapDatabaseRelationship extension.

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    Declaration

    Objective-C

    @interface YapDatabaseRelationshipOptions : NSObject <NSCopying>

    Swift

    class YapDatabaseRelationshipOptions : NSObject, NSCopying

  • Undocumented

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    Declaration

    Objective-C

    @interface YapDatabaseRelationshipEdge : NSObject <NSCopying>

/**
 * Returns an edge with the given name, destination & nodeDeleteRules.
 * 
 * This method is suitable for use with the YapDatabaseRelationshipNode protocol.
 * When using this protocol, the source object is directly queried by the YapDatabaseRelationship extension.
 * Thus the extension already knows what the source node is,
 * and so the source node information (sourceKey & sourceCollection) doesn't need to be explicitly set on the edge.
 * 
 * This method is not suitable for use with manual edge management.
 * When manually adding an edge, you must fully specify the source node.
 */
+ (instancetype)edgeWithName:(NSString *)name
              destinationKey:(NSString *)destinationKey
                  collection:(nullable NSString *)destinationCollection
             nodeDeleteRules:(YDB_NodeDeleteRules)rules;

/**
 * Returns an edge with the given name, destinationFileURL & nodeDeleteRules.
 * 
 * When using a destinationFileURL, only a subset of the nodeDeleteRules apply.
 * Specifically only the following work:
 * - YDB_DeleteDestinationIfSourceDeleted
 * - YDB_DeleteDestinationIfAllSourcesDeleted
 *
 * This method is suitable for use with the YapDatabaseRelationshipNode protocol.
 * When using this protocol, the source object is directly queried by the YapDatabaseRelationship extension.
 * Thus the extension already knows what the source node is,
 * and so the source node information (sourceKey & sourceCollection) doesn't need to be explicitly set on the edge.
 * 
 * This method is not suitable for use with manual edge management.
 * When directly adding an edge, you must fully specify the source node.
 */
+ (instancetype)edgeWithName:(NSString *)name
          destinationFileURL:(NSURL *)destinationFileURL
             nodeDeleteRules:(YDB_NodeDeleteRules)rules;

/**
 * Returns a fully specified edge.
 * 
 * This method is suitable for use with manual edge management.
 * 
 * If you're using the YapDatabaseRelationshipNode protocol, then you can use the shorter version of this method
 * which doesn't specify the source node. This is because the source node is implied with the
 * YapDatabaseRelationshipNode protocol, and thus doesn't need to be explicitly specified in the edge.
 */
+ (instancetype)edgeWithName:(NSString *)name
                   sourceKey:(NSString *)sourceKey
                  collection:(nullable NSString *)sourceCollection
              destinationKey:(NSString *)destinationKey
                  collection:(nullable NSString *)destinationCollection
             nodeDeleteRules:(YDB_NodeDeleteRules)rules;

/**
 * Returns a fully specified edge.
 * 
 * When using a destinationFileURL, only a subset of the nodeDeleteRules apply.
 * Specifically only the following work:
 * - YDB_DeleteDestinationIfSourceDeleted
 * - YDB_DeleteDestinationIfAllSourcesDeleted
 *
 * This method is suitable for use with manual edge management.
 *
 * If you're using the YapDatabaseRelationshipNode protocol, then you can use the shorter version of this method
 * which doesn't specify the source node. This is because the source node is implied with the
 * YapDatabaseRelationshipNode protocol, and thus doesn't need to be explicitly specified in the edge.
 */
+ (instancetype)edgeWithName:(NSString *)name
                   sourceKey:(NSString *)sourceKey
                  collection:(nullable NSString *)sourceCollection
          destinationFileURL:(NSURL *)destinationFileURL
             nodeDeleteRules:(YDB_NodeDeleteRules)rules;

#pragma mark Init

/**
 * For documentation @see edgeWithName:destinationKey:collection:nodeDeleteRules:
 */
- (id)initWithName:(NSString *)name
    destinationKey:(NSString *)key
        collection:(nullable NSString *)collection
   nodeDeleteRules:(YDB_NodeDeleteRules)rules;

/**
 * For documentation @see edgeWithName:destinationFileURL:nodeDeleteRules:
 */
- (id)initWithName:(NSString *)name destinationFileURL:(NSURL *)destinationFileURL
                                       nodeDeleteRules:(YDB_NodeDeleteRules)rules;

/**
 * For documentation @see edgeWithName:sourceKey:collection:destinationKey:collection:nodeDeleteRules:
 */
- (id)initWithName:(NSString *)name
         sourceKey:(NSString *)sourceKey
        collection:(nullable NSString *)sourceCollection
    destinationKey:(NSString *)destinationKey
        collection:(nullable NSString *)destinationCollection
   nodeDeleteRules:(YDB_NodeDeleteRules)rules;

/**
 * For documentation @see edgeWithName:sourceKey:collection:destinationFileURL:nodeDeleteRules:
 */
- (id)initWithName:(NSString *)name sourceKey:(NSString *)sourceKey
                                   collection:(nullable NSString *)sourceCollection
                           destinationFileURL:(NSURL *)destinationFileURL
                              nodeDeleteRules:(YDB_NodeDeleteRules)rules;

#pragma mark Properties

@property (nonatomic, copy, readonly) NSString *name;

@property (nonatomic, copy, readonly) NSString *sourceKey;
@property (nonatomic, copy, readonly) NSString *sourceCollection;

@property (nonatomic, copy, readonly) NSString *destinationKey;
@property (nonatomic, copy, readonly) NSString *destinationCollection;

@property (nonatomic, copy, readonly) NSURL *destinationFileURL;

@property (nonatomic, assign, readonly) YDB_NodeDeleteRules nodeDeleteRules;

/**
 * NO if the edge was created via the YapDatabaseRelationshipNode protocol.
 * YES if the edge was created via "manual edge management" methods.
 */
@property (nonatomic, assign, readonly) BOOL isManualEdge;

@end

    Swift

    class YapDatabaseRelationshipEdge : NSObject, NSCopying

  • There are 2 techniques you may use to add edges to the relationship graph:

    • Use the YapDatabaseRelationshipNode protocol
    • Manually manage the edges by adding / removing them yourself

    You are welcome to use either technique. In fact you can use them both simultaneously. Which you choose may simply be whichever works best depending on the situation.

    The YapDatabaseRelationshipNode protocol works quite simply:

    Any object that is stored in the database may optionally implement this protocol in order to specify a list of relationships that apply to it. The object just needs to: 1.) Add the YapDatabaseRelationshipNode protocol to its declared list of protocols (in header file) 2.) Implement the yapDatabaseRelationshipEdges method

    When the object is inserted or updated in the database, the YapDatabaseRelationshipExtension will automatically invoke the yapDatabaseRelationshipEdges method to get the list of edges. It then inserts the list of edges into the database (if object was inserted), or updates the previously inserted list (if object was updated).

    Typically this protocol is convenient to use if:

  • Your objects already contain identifiers that can be used to create the edges you desire

  • You’d like to be able to delete objects in the database by simply setting identifier properties to nil

    • See

    YapDatabaseRelationshipEdge

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    Declaration

    Objective-C

    @protocol YapDatabaseRelationshipNode

    Swift

    protocol YapDatabaseRelationshipNode