子查询和IN语句在领域 [英] Subquery and IN Statement in realm

问题描述

我有三个领域对象。部门，部门和用户。 section是某个部门的一个子部门。但是每个部门和每个部门都会有用户。

I have three realm objects. Department, section and user. section is a kind of sub department in a department. But there will be users under each section and each department.

@interface Department : RLMObject

@property NSString *name;
@property BOOL isCollapsed;

@property (nonatomic, strong) RLMArray<Section> *sections;
@property (nonatomic, strong) RLMArray<User> *users;

@end

@interface Section : RLMObject

@property NSString *name;
@property BOOL isCollapsed;
@property RLMArray<User> *users;

@end 

@interface User : RLMObject

@property NSString *department;
@property NSString *email;
@property NSString *firstname;
@property NSString *lastname;
@property NSString *fullname;

@end

我想要做的是，我想搜索所有名字和姓氏都包含a且与部门和部门相关联的用户。

What i want to do is, I want to search all the user whose first name and last name contains "a" and linked with department and section.

现在我正在做的是

searchText = [searchText lowercaseString];

RLMResults *sections = [Section objectsWhere:
                        [NSString stringWithFormat:@"SUBQUERY(users, $user, $user.fullname contains '%@' OR $user.nickname contains '%@').@count > 0",searchText,searchText]];

NSMutableArray *sectionNames = [NSMutableArray array];

for (Section *section in sections)
{
    [sectionNames addObject:section.name];
}

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SUBQUERY(sections, $section, $section.name IN %@).@count > 0", sectionNames];

RLMResults *filteredDepartments = [[Department objectsWithPredicate:predicate] sortedResultsUsingProperty:@"name" ascending:YES];

NSPredicate *pred = [NSPredicate predicateWithFormat:@"SUBQUERY(users, $user, $user.fullname contains %@ OR $user.nickname contains %@).@count > 0",searchText,searchText];
RLMResults *departments = [filteredDepartments objectsWithPredicate:pred];

目前问题是部分数组中有两个部分，但是 deparments 结果，它返回null。请帮忙。谢谢。

Right now the issue is there is two sections in sections array but in the deparments results, it returns null. please help. thanks.

注意：如果一个用户已经属于某个部分，那么该用户将不会被包含在部门中。

Note: If one user already belongs to section then that user will not be include in department.

推荐答案

也许你不需要使用子查询。更简单地说，您可以在查询中使用 ANY ，如下所示：

Maybe you do not need to use subquery. More simply, you can use ANY in query like the following:

[Department objectsWhere:
    @"ANY users.firstname CONTAINS %@ OR ANY users.lastname CONTAINS %@ OR ANY sections.users.firstname CONTAINS %@ OR ANY sections.users.lastname CONTAINS %@", searchText, searchText, searchText, searchText];

但我认为使用反向关系更容易。在Realm中，反向关系由 RLMLinkingObjects 定义。
您可以向用户类添加反向关系，如下所示：

But I think using inverse relationships is more easier. In Realm, inverse relationships is defined with RLMLinkingObjects. You can add inverse relationships to User class as follows:

@interface User : RLMObject

...

@property (readonly) RLMLinkingObjects *departments;
@property (readonly) RLMLinkingObjects *sections;

@end

@implementation User

+ (NSDictionary *)linkingObjectsProperties {
    return @{@"departments": [RLMPropertyDescriptor descriptorWithClass:Department.class propertyName:@"users"],
             @"sections": [RLMPropertyDescriptor descriptorWithClass:Section.class propertyName:@"users"]};
}

@end

然后你可以得到部门和用户所属的部分来自用户的属性，如下所示：

Then you can get departments and sections where the user belongs to from User's property, like the following:

RLMResults *users = [User objectsWhere:@"firstname CONTAINS %@ OR lastname CONTAINS %@" , searchText, searchText];
for (User *user in users) {
    NSLog(@"%@", user.departments);
    NSLog(@"%@", user.sections);
}

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