iPhone CoreData funky fetch-request: 我想构建函数来检索我的产品的Unique-CategoryCodes数组 我有Entity“Product”并且有一个字段(Property)类别。 当然,类别是与类别实体的关系。CoreData - 来自subEntity ....的唯一值?
此,如果我的功能:
- (NSArray *)uniqueCategoriesWithQuery:(NSString *)query {
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Product" inManagedObjectContext:[self managedObjectContext]];
NSDictionary *entityProperties = [entity propertiesByName];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entity];
[request setReturnsDistinctResults:YES];
[request setPropertiesToFetch:[NSArray arrayWithObject:[entityProperties objectForKey:@"Code"]]];
[request setResultType:NSDictionaryResultType];
[request setIncludesSubentities:YES];
[request setIncludesPropertyValues:YES];
NSError *fetchError = nil;
NSArray *result = [[self managedObjectContext] executeFetchRequest:request error:&fetchError];
DebugLog(@"%@", result);
if (fetchError == nil && [result count] > 0) {
return result;
}
return nil;
}
MyResult: 2010-12-10 05:55:33.683接入点内部协议[3453:307] - [ShoppingHelper uniqueCategoriesWithQuery:] [1193线] ( { 类别= “0x495a200”; },{ 类别 = “0x4959ce0”; } )
代码运行良好,但我根本无法使用结果。我有我的类别...但ID'而不是NSStrings ..如何消费它?可能我应该使用: [请求setPropertiesToFetch:[NSArray arrayWithObject:[entityProperties objectForKey:[“Categories.Code”]]];
获取不同NSDictionary中的NSString?
或
寻找类别BY ID - 怎么做?
谢谢,但如果我返回管理对象“setReturnsDistinctResults:YES”不起作用 - 我得到所有的产品。我只需要过滤产品表的唯一类别。像SELECT DISTINCT类似于产品名称类似于'%mylikeString%'的产品。 – Cezar 2010-12-10 14:05:40