CoreData 一对多关系

[dmelon]

CoreData中的“一对多”的关系使用NSSet而不是NSArray。这样的话，一个NSManagedObject中的关系属性（NSSet *类型），就没法利用objectArrayWithKeyValuesArray来自动生成对象了。请问有什么解决方法吗？

[chengleyi]

我也有这样的问题，请问如何解决。。。

[jaysonjh]

老师与学生一对多关系

NSDictionary *techerAndStudents = @{
                                        @"uid":[[NSUUID UUID] UUIDString],
                                        @"name":@"jayson",
                                        @"students":@[
                                                @{
                                                    @"uid":[[NSUUID UUID] UUIDString],
                                                    @"name":@"11",
                                                    },
                                                @{
                                                    @"uid":[[NSUUID UUID] UUIDString],
                                                    @"name":@"12",
                                                    }
                                                ],
                                        };

    [MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
        [Teacher setupObjectClassInArray:^NSDictionary *{
            return @{@"students":[Student class]};
        }];
        Teacher *teacher = [Teacher objectWithKeyValues:techerAndStudents context:localContext];
        //此处students为nil，还得加入以下才可实现coredata的一对多。
        Student *s1 = [Student objectWithKeyValues:@{@"uid":[[NSUUID UUID] UUIDString],@"name":@"11",} context:localContext];
        Student *s2 = [Student objectWithKeyValues:@{@"uid":[[NSUUID UUID] UUIDString],@"name":@"12",} context:localContext];
        [teacher addStudentsObject:s1];
        [teacher addStudentsObject:s2];
        NSLog(@"Teacher:%@,%@,%@",teacher.name,teacher.uid,teacher.students);
    }];
NSDictionary *techerAndStudents = @{
                                        @"uid":[[NSUUID UUID] UUIDString],
                                        @"name":@"jayson",
                                        @"students":@[
                                                @{
                                                    @"uid":[[NSUUID UUID] UUIDString],
                                                    @"name":@"11",
                                                    },
                                                @{
                                                    @"uid":[[NSUUID UUID] UUIDString],
                                                    @"name":@"12",
                                                    }
                                                ],
                                        };

    [MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) {
        [Teacher setupObjectClassInArray:^NSDictionary *{
            return @{@"students":[Student class]};
        }];
        Teacher *teacher = [Teacher objectWithKeyValues:techerAndStudents context:localContext];
        Student *s1 = [Student objectWithKeyValues:@{@"uid":[[NSUUID UUID] UUIDString],@"name":@"11",} context:localContext];
        Student *s2 = [Student objectWithKeyValues:@{@"uid":[[NSUUID UUID] UUIDString],@"name":@"12",} context:localContext];
        [teacher addStudentsObject:s1];
        [teacher addStudentsObject:s2];
        NSLog(@"Teacher:%@,%@,%@",teacher.name,teacher.uid,teacher.students);
    }];

跟踪代码在

// 2.如果是模型属性
            MJPropertyType *type = property.type;
            Class typeClass = type.typeClass;
            Class objectClass = [property objectClassInArrayForClass:[self class]];
           //fromFoundation为NO,typeClass为NSSet 结果就无法继续再对NSSet中的对象进行映射了
            if (!type.isFromFoundation && typeClass) {
                value = [typeClass objectWithKeyValues:value context:context error:error];
            }

@CoderMJLee 有更好的方式去解决一对多的问题吗？

[yuhanle]

@jaysonjh 像你这种写法可以达到目的吗？
我试了试，感觉有些问题

[wolfcon]

Duplicate of #43