核心数据 - 过滤使用谓词

Question

一个一对多的关系，我有以下两个实体在我的核心数据模型：

Manufacture {name, ...other attributes} 
Product {name, .... other attributes} 

我已经建立了一对多的关系：

Manufacturer.manufactures <------>> Product.manufacturedBy 

我我试图构建一个谓词来返回属于制造商的与搜索字符串匹配的所有产品。例如。如果有两个制造商，“国王螺母”和“女王坚果”，则搜索“坚果”应该返回由国王螺母和皇后螺母制造的所有产品。

当我的过滤器位于产品实体上时，我的谓词完美地工作，但是当在制造商实体上过滤时，我无法获取任何谓词。结果集是空的。

NSEntityDescription *entity = [NSEntityDescription entityForName:@"Product" inManagedObjectContext:[GBKDB context]]; 
searchValue = @"nut"; 
NSString *wildcardString = [NSString stringWithFormat:@"*%@*", searchValue]; 

我曾尝试以下：

predicate = [NSPredicate predicateWithFormat:@"manufacturedBy.name CONTAINS[cd] %@",searchValue]; 
    predicate = [NSPredicate predicateWithFormat:@"manufacturedBy.name like %@",wildcardString]; 
    predicate = [NSPredicate predicateWithFormat:@"manufacturedBy.name matches %@",wildcardString]; 
    predicate = [NSPredicate predicateWithFormat:@"ALL manufacturedBy.name like %@",wildcardString]; 
    predicate = [NSPredicate predicateWithFormat:@"ALL manufacturedBy.name like[cd] %@",@wildcardString]; 

Answer 1

在this文件看看苹果。它做了一个例子，你正在试图用“ANY”谓词来做什么。

Answer 2

为了得到由制造商包含“坚果”的名字制造Product S，你的要求应该是这样的：

NSString* searchVal = @"nut"; 
NSFetchRequest* r = [[NSFetchRequest alloc] initWithEntityName:@"Product"]; 
[r setPredicate:[NSPredicate predicateWithFormat:@"manufacturedBy.name CONTAINS[cd] %@",searchVal]]; 

与含“螺母”你的要求应该像产品名获得Manufacturer S：

NSString* searchVal = @"nut"; 
NSFetchRequest* r = [[NSFetchRequest alloc] initWithEntityName:@"Manufacture"]; 
[r setPredicate:[NSPredicate predicateWithFormat:@"ANY manufactures.name CONTAINS[cd] %@",searchVal]]; 

如果结果集是空的，这可能是由于没有物体回答谓词（包含子“螺母”）。
尝试添加一些具有已知名称和测试的假实体。

编辑： 这是代码，你可以使用测试：

typedef void(^config_block_t)(id); 

- (void) synthesizeObjectsOfEntity:(NSString*)entity 
          context:(NSManagedObjectContext*)context 
          count:(NSUInteger)count 
         configBlock:(config_block_t)configBlock 
{ 
    for (;count;--count) { 
     NSManagedObject* object = [NSEntityDescription insertNewObjectForEntityForName:entity 
                   inManagedObjectContext:context]; 
     configBlock(object); 
    } 
} 

- (void) synthesizeProductsAndManufacturersInContext:(NSManagedObjectContext*)context 
{ 
    NSMutableArray* manufacturers = [NSMutableArray new]; 
    [self synthesizeObjectsOfEntity:@"Manufactur" 
          context:context 
           count:10 
         configBlock:^(Manufactur* m) { 
          m.name = [NSString stringWithFormat:@"m-%u%u%u",arc4random()%10,arc4random()%10,arc4random()%10]; 
          [manufacturers addObject:m]; 
         }]; 
    [self synthesizeObjectsOfEntity:@"Product" 
          context:context 
           count:100 
         configBlock:^(Product* p) { 
          p.name = [NSString stringWithFormat:@"p-%u%u%u",arc4random()%10,arc4random()%10,arc4random()%10]; 
          p.manufacturedBy = manufacturers[arc4random() % [manufacturers count]]; 
         }]; 
    [context save:NULL]; 
    [context reset]; 
    NSString* searchVal = @"3"; 
    NSFetchRequest* r = [[NSFetchRequest alloc] initWithEntityName:@"Product"]; 
    [r setPredicate:[NSPredicate predicateWithFormat:@"manufacturedBy.name CONTAINS[cd] %@",searchVal]]; 
    NSArray* match = [context executeFetchRequest:r error:NULL]; 
    NSLog(@"matched: %u",[match count]); 
}