Reimplement inverseMapping so that it no longer sucks. fixes #864, #1058

* Inversing non intelligently walks the mapping graph, ensuring that cyclic graphs are resolved properly * Copy all attributes from the parent to the inverse mapping (date formatters, etc)
2026-04-23 04:20:21 +08:00 · 2012-12-22 16:36:55 -05:00
parent b78deb3eed
commit 7984d4f2ac
3 changed files with 94 additions and 33 deletions
--- a/Code/ObjectMapping/RKObjectMapping.m
+++ b/Code/ObjectMapping/RKObjectMapping.m
@@ -18,6 +18,7 @@
 //  limitations under the License.
 //

+#import <CoreFoundation/CoreFoundation.h>
 #import "RKObjectMapping.h"
 #import "RKRelationshipMapping.h"
 #import "RKPropertyInspector.h"
@@ -30,13 +31,71 @@ typedef NSString * (^RKSourceToDesinationKeyTransformationBlock)(RKObjectMapping

 // Constants
 NSString * const RKObjectMappingNestingAttributeKeyName = @"<RK_NESTING_ATTRIBUTE>";
-static NSUInteger RKObjectMappingMaximumInverseMappingRecursionDepth = 100;

 // Private declaration
 NSDate *RKDateFromStringWithFormatters(NSString *dateString, NSArray *formatters);

 static RKSourceToDesinationKeyTransformationBlock defaultSourceToDestinationKeyTransformationBlock = nil;

+@interface RKObjectMapping (Copying)
+- (void)copyPropertiesFromMapping:(RKObjectMapping *)mapping;
+@end
+
+@interface RKMappingInverter : NSObject
+@property (nonatomic, strong) RKObjectMapping *mapping;
+@property (nonatomic, strong) NSMutableDictionary *invertedMappings;
+
+- (id)initWithMapping:(RKObjectMapping *)mapping;
+- (RKObjectMapping *)inverseMapping;
+@end
+
+@implementation RKMappingInverter
+
+- (id)initWithMapping:(RKObjectMapping *)mapping
+{
+    self = [self init];
+    if (self) {
+        self.mapping = mapping;
+        self.invertedMappings = [NSMutableDictionary dictionary];
+    }
+    return self;
+}
+
+- (RKObjectMapping *)invertMapping:(RKObjectMapping *)mapping
+{
+    // Use an NSValue to obtain a non-copied key into our inversed mappings dictionary
+    NSValue *dictionaryKey = [NSValue valueWithNonretainedObject:mapping];
+    RKObjectMapping *inverseMapping = [self.invertedMappings objectForKey:dictionaryKey];
+    if (inverseMapping) return inverseMapping;
+    
+    inverseMapping = [RKObjectMapping mappingForClass:[NSMutableDictionary class]];
+    [self.invertedMappings setObject:inverseMapping forKey:dictionaryKey];
+    [inverseMapping copyPropertiesFromMapping:mapping];
+    
+    for (RKAttributeMapping *attributeMapping in mapping.attributeMappings) {
+        [inverseMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:attributeMapping.destinationKeyPath toKeyPath:attributeMapping.sourceKeyPath]];
+    }
+    
+    for (RKRelationshipMapping *relationshipMapping in mapping.relationshipMappings) {
+        RKObjectMapping *mapping = (RKObjectMapping *) relationshipMapping.mapping;
+        if (! [mapping isKindOfClass:[RKObjectMapping class]]) {
+            RKLogWarning(@"Unable to generate inverse mapping for relationship '%@': %@ relationships cannot be inversed.", relationshipMapping.sourceKeyPath, NSStringFromClass([mapping class]));
+            continue;
+        }
+        RKMapping *inverseRelationshipMapping = [self invertMapping:mapping];
+        if (inverseRelationshipMapping) [inverseMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:relationshipMapping.destinationKeyPath toKeyPath:relationshipMapping.sourceKeyPath withMapping:inverseRelationshipMapping]];
+    }
+    
+    return inverseMapping;
+}
+
+- (RKObjectMapping *)inverseMapping
+{
+    return [self invertMapping:self.mapping];
+}
+
+@end
+
@interface RKPropertyMapping ()
@property (nonatomic, weak, readwrite) RKObjectMapping *objectMapping;
@end
@@ -77,21 +136,26 @@ static RKSourceToDesinationKeyTransformationBlock defaultSourceToDestinationKeyT
    return self;
 }

+- (void)copyPropertiesFromMapping:(RKObjectMapping *)mapping
+{
+    self.setDefaultValueForMissingAttributes = mapping.setDefaultValueForMissingAttributes;
+    self.setNilForMissingRelationships = mapping.setNilForMissingRelationships;
+    self.forceCollectionMapping = mapping.forceCollectionMapping;
+    self.performKeyValueValidation = mapping.performKeyValueValidation;
+    self.dateFormatters = mapping.dateFormatters;
+    self.preferredDateFormatter = mapping.preferredDateFormatter;
+    self.sourceToDestinationKeyTransformationBlock = self.sourceToDestinationKeyTransformationBlock;
+}
+
 - (id)copyWithZone:(NSZone *)zone
 {
    RKObjectMapping *copy = [[[self class] allocWithZone:zone] init];
    copy.objectClass = self.objectClass;
-    copy.setDefaultValueForMissingAttributes = self.setDefaultValueForMissingAttributes;
-    copy.setNilForMissingRelationships = self.setNilForMissingRelationships;
-    copy.forceCollectionMapping = self.forceCollectionMapping;
-    copy.performKeyValueValidation = self.performKeyValueValidation;
-    copy.dateFormatters = self.dateFormatters;
-    copy.preferredDateFormatter = self.preferredDateFormatter;
+    [copy copyPropertiesFromMapping:self];
    copy.mutablePropertyMappings = [NSMutableArray new];
-    copy.sourceToDestinationKeyTransformationBlock = self.sourceToDestinationKeyTransformationBlock;

    for (RKPropertyMapping *propertyMapping in self.propertyMappings) {
-        [copy addPropertyMapping:propertyMapping];
+        [copy addPropertyMapping:[propertyMapping copy]];
    }

    return copy;
@@ -264,29 +328,10 @@ static RKSourceToDesinationKeyTransformationBlock defaultSourceToDestinationKeyT
    }
 }

- (instancetype)inverseMappingAtDepth:(NSInteger)depth
-{
-    NSAssert(depth < RKObjectMappingMaximumInverseMappingRecursionDepth, @"Exceeded max recursion level in inverseMapping. This is likely due to a loop in the serialization graph. To break this loop, specify one-way relationships by setting serialize to NO in mapKeyPath:toRelationship:withObjectMapping:serialize:");
-    RKObjectMapping *inverseMapping = [RKObjectMapping mappingForClass:[NSMutableDictionary class]];
-    for (RKAttributeMapping *attributeMapping in self.attributeMappings) {
-        [inverseMapping addPropertyMapping:[RKAttributeMapping attributeMappingFromKeyPath:attributeMapping.destinationKeyPath toKeyPath:attributeMapping.sourceKeyPath]];
-    }
-
-    for (RKRelationshipMapping *relationshipMapping in self.relationshipMappings) {
-        RKMapping *mapping = relationshipMapping.mapping;
-        if (! [mapping isKindOfClass:[RKObjectMapping class]]) {
-            RKLogWarning(@"Unable to generate inverse mapping for relationship '%@': %@ relationships cannot be inversed.", relationshipMapping.sourceKeyPath, NSStringFromClass([mapping class]));
-            continue;
-        }
-        [inverseMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:relationshipMapping.destinationKeyPath toKeyPath:relationshipMapping.sourceKeyPath withMapping:[(RKObjectMapping *)mapping inverseMappingAtDepth:depth+1]]];
-    }
-
-    return inverseMapping;
-}
-
 - (instancetype)inverseMapping
 {
-    return [self inverseMappingAtDepth:0];
+    RKMappingInverter *mappingInverter = [[RKMappingInverter alloc] initWithMapping:self];
+    return [mappingInverter inverseMapping];
 }

 - (void)addAttributeMappingFromKeyOfRepresentationToAttribute:(NSString *)attributeName