核心数据可变的NSArray的ID [英] Core Data Transformable NSArray of IDs
问题描述
我有一个CoreData实体类X,它存储一个NSString ID的NSArray,在一个可变属性(让我们说someIDs)...
NSString ID,如何在其someID属性中查找(使用谓词)所有包含ID的实体X?
注意:我知道你不能。一个transformable属性存储为SQLite存储文件中的数据blob(使用 NSCoding
方法)。核心数据获取请求(转换为SQLite查询)
无法访问可转换属性的内容。
如果您不想要使用一对多关系,那么您只能抓取所有对象并过滤抓取的 NSArray
。
I have an CoreData entity class X, which stores an NSArray of NSString IDs, inside a transformable attribute (lets say someIDs)...
Given an NSString ID, how can i find (using Predicate) all entities X, which contains the ID, in their someIDs attribute?
Note: i know about relationships (so no need to propose using a relationship) etc. but what to do in this case?
You can't. A transformable attribute is store as a data blob in the SQLite store file (using NSCoding
methods). The Core Data fetch request (which is translated to a SQLite query)
has no access to the contents of the transformable attribute.
If you don't want to use a to-many relationship then you can only fetch all objects and filter the fetched NSArray
.
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