如何在 NSPredicate 中使用“ANY”聚合操作来过滤 CoreData 多对多关系

Question

数据模型：

我正在尝试获取所有具有 contentType.selected == 1 的“解决方案”

证明结构和数据设置正确

--ContentType 实体数据

--解决方案实体数据

--ContentType 关系

健全性检查（无谓词）

(lldb) po self.solutionTreeFetchedResultsController.fetchedObjects
<_PFArray 0x7fe958ea2b10>(
<Solutions: 0x7fe95b1415e0> (entity: Solutions; id: 0xd00000000ac00006 <x-coredata://2799F23D-B41B-48EF-923A-9E2C2A0C10B5/Solutions/p688> ; data: <fault>),
<Solutions: 0x7fe95b141b10> (entity: Solutions; id: 0xd00000000ac40006 <x-coredata://2799F23D-B41B-48EF-923A-9E2C2A0C10B5/Solutions/p689> ; data: <fault>)

......切断其余的，但这里有 49 个。）

(lldb) po [self.solutionTreeFetchedResultsController.fetchedObjects count]
49

方法 1（最直接）

NSArray *contentTypes = self.contentTypeFetchedResultsController.fetchedObjects;
request.predicate = [NSPredicate predicateWithFormat:@"ANY contentType IN %@", contentTypes];

po contentTypes
<_PFArray 0x7fa4b6018680>(
<ContentType: 0x7fa4b60181c0> (entity: ContentType; id: 0xd0000000006c0004 <x-coredata://2799F23D-B41B-48EF-923A-9E2C2A0C10B5/ContentType/p27> ; data: <fault>),
<ContentType: 0x7fa4b6018620> (entity: ContentType; id: 0xd000000000700004 <x-coredata://2799F23D-B41B-48EF-923A-9E2C2A0C10B5/ContentType/p28> ; data: <fault>)
)

po self.solutionTreeFetchedResultsController.fetchedObjects
<__NSArrayI 0x7fa4b3c1ddf0>(

)

方法二

 request.predicate = [NSPredicate
                         predicateWithFormat:@"SUBQUERY(contentType, $contenttype, $contenttype IN %@).@count = %d", contentTypes, [contentTypes count]];

(lldb) po self.solutionTreeFetchedResultsController.fetchedObjects
<__NSArrayI 0x7fcea3e01350>(

)

方法3

NSMutableArray *predicates = [[NSMutableArray alloc] init];
for (ContentType *contentType in contentTypes) {
    [predicates addObject:[NSPredicate predicateWithFormat:@"ANY contentType.name MATCHES %@", contentType.name]];
}

[predicates addObject:[NSPredicate predicateWithFormat:@"active == 1"]];
NSPredicate *compoundPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];
request.predicate = compoundPredicate;

(lldb) po self.solutionTreeFetchedResultsController.fetchedObjects
<__NSArrayI 0x7f8f9850bbf0>(

)

如果您仅选择 1 个 contentType，则方法 3 排序有效，但如果您选择了 1 个以上，则它不会返回任何内容。

我迷路了，不知道还能尝试什么。任何投入将不胜感激！如果您还需要什么，请告诉我。谢谢！

已经尝试了这篇文章中的大多数解决方案，但似乎没有任何方法 100% 有效 How to use the "ALL" aggregate operation in a NSPredicate to filter a CoreData-based collection

Answer 1

如果您的问题是如何使用给定的数据模型获取所有具有 contentType.selected == 1 的“解决方案”，谓词：

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(ANY contentType.selected == $SELECTVALUE)"];

为我工作。将其定义为模板并像这样将其添加到模型中......

- (NSManagedObjectModel *)managedObjectModel {
 // The managed object model for the application. It is a fatal error for the application not to be able to find and load its model.
 if (_managedObjectModel != nil) {
     return _managedObjectModel;
 }
 NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"ANYApp" withExtension:@"momd"];

 _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

 NSEntityDescription *entity = [[_managedObjectModel entitiesByName] objectForKey:@"Solutions"];

 NSFetchRequest *template = [[NSFetchRequest alloc] init];

 [template setEntity:entity];

 NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(ANY contentType.selected == $SELECTVALUE)"];

 [template setPredicate:predicate];

 [_managedObjectModel setFetchRequestTemplate:template forName:@"SolutionsTemplate"];

 return _managedObjectModel;
}

像这样定义 fetch 方法 ....

- (NSArray *)fetchAllSolutionsBySelected:(NSNumber *)selected
 {
  NSError *error = nil;

 NSString *templateName=@"SolutionsTemplate";

 NSDictionary *substitutionDictionary = [NSDictionary dictionaryWithObjectsAndKeys:selected, @"SELECTVALUE", nil];

 NSFetchRequest *fetchRequest = [[_app managedObjectModel] fetchRequestFromTemplateWithName:templateName substitutionVariables:substitutionDictionary];

 NSArray *results = [[_app managedObjectContext] executeFetchRequest:fetchRequest error:&error];

 return results;
}

我终于可以获取所有具有 contentType.selected == 1 的“解决方案”：

NSArray *solutionsWithContentSelected=[self fetchAllSolutionsBySelected:@(1)];

您可以在此处找到 XCode 6.1 iOS 8.1 项目：ANYApp Project。希望对你有帮助。