从coredata中检索数据,其中实体具有NSSet

Question

我正在尝试使用谓词来获取我想要搜索的数据所在的数据 NSSet

@property (nonatomic, retain) NSSet *categories;
@property (nonatomic, retain) NSString *otherDetails;
@property (nonatomic, retain) NSNumber *id;

该NSSet类别是从另一个实体组成,包含:

@property (nonatomic, retain) NSString *name;
@property (nonatomic, retain) NSNumber *id;

然后尝试通过谓词得到这个

NSFetchRequest *fetcher =[NSFetchRequest fetchRequestWithEntityName:@"MyEntity"];
fetcher.predicate = [NSPredicate predicateWithFormat:@categories in  %@", catList];

其中catList是:

NSmutableArray *catList = [[NSMutableArray alloc] init];

并填充数据

这就是给我以下错误

'NSInvalidArgumetException', reason: 'unimplemented SQL generation for predicate: (categories IN {"this", "that"});

我尝试将其更改为使用这样的NSSet字段

fetcher.predicate = [NSPredicate predicateWithFormat:@categories.name in  %@", catList];

但这没用.

如果我更改谓词使用NSString它不会出错,但由于数据不同,不会返回任何结果.

fetcher.predicate = [NSPredicate predicateWithFormat:@categories in  %@", catList];

那么我该怎么做才能使用谓词来进行查询NSSet呢？

更新:我已经找到了这个如何通过在CoreData中使用predicateWithFormat来检查对象是否在NSSet对象中？这可能会解决发布的问题,但我已经过多地解释了这个问题.

我实际拥有的是另一个实体,我正在搜索一大堆细节,然后与我的"MyEntity"实体有多对一的关系.

MySearchEntity:

@property (nonatomic, retain) NSNumber *searchField1;
@property (nonatomic, retain) NSNumber *searchField2;
@property (nonatomic, retain) MyEntity *myEntity;
@property (nonatomic, retain) NSNumber *id;

和像这样的fetchrequest

NSFetchRequest *fetcher =[NSFetchRequest fetchRequestWithEntityName:@"MySearchEntity"];
fetcher.predicate = [NSPredicate predicateWithFormat:@"myEntity.otherDetails CONTAINS %@ && searchField1 <= %f && searchField2 >= %f && myEntity.categories.name in  %@", catList];

所以声明的其余部分有效但我仍然无法通过MyEntities过滤它与类别的多对多关系.

Answer 1

要查找MySearchEntity相关MyEntity对象在给定集中至少有一个类别的对象,可以使用谓词

NSArray *catList = array of Category objects;
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY myEntity.categories IN %@", catList];

或者,如果类别是按名称给出的:

NSArray *catList = array of NSString objects;
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY myEntity.categories.name IN %@", catList];