核心數據 - 過濾使用謂詞

Question

一個一對多的關係，我有以下兩個實體在我的核心數據模型：

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

我已經建立了一對多的關係：

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

我我試圖構建一個謂詞來返回屬於製造商的與搜索字符串匹配的所有產品。例如。如果有兩個製造商，「國王螺母」和「女王堅果」，則搜索「堅果」應該返回由國王螺母和皇后螺母製造的所有產品。

當我的過濾器位於產品實體上時，我的謂詞完美地工作，但是當在製造商實體上過濾時，我無法獲取任何謂詞。結果集是空的。

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

我曾嘗試以下：

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文件看看蘋果。它做了一個例子，你正在試圖用「ANY」謂詞來做什麼。

Answer 2

爲了得到由製造商包含「堅果」的名字製造Product S，你的要求應該是這樣的：

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

與含「螺母」你的要求應該像產品名獲得Manufacturer S：

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

如果結果集是空的，這可能是由於沒有物體回答謂詞（包含子「螺母」）。
嘗試添加一些具有已知名稱和測試的假實體。

編輯： 這是代碼，你可以使用測試：

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]); 
}