如何创建SourceList来显示Core Data ToMany关系？ [英] How to create SourceList to show Core Data ToMany relations?

问题描述

来自iOS，我被困在NSOutlineView作为源列表，我已经读了很多资源，但不能把握它清楚。

Coming from iOS, I am stuck at NSOutlineView as Source list, I have read many resources but cannot grasp it clearly.

我想要的是，只是为了显示coreData使用NSTreeController作为sourceList的ToMany关系。我正在将数据从文本文件保存到磁盘。
实体和关系如下：

What I want is, just to show coreData ToMany relationship as sourceList using NSTreeController. I am persisting data from text file to disk. Entities and relations are as follow:

Group >> Item >> Description

Group >> Item >> Description

SourceList示例：

SourceList Example:

我的应用程序不允许用户创建任何新的实体，只是查看从TextFile保存的内容。我可以做到这一点NSArrayController，但我需要显示数据在单个表与层次结构。
在NSArrayController中，我只需要将受管对象上下文绑定到参数和对象控制器到实体名称。在TableView上，我需要将内容和选择索引绑定到NSArrayController。

My app do not allow user to create any new Entity, just to view what saved from TextFile. I can do this by NSArrayController but I need to show data in single table with hierarchy. In NSArrayController, I only needed to bind managed object context to Parameter and and object controller to Entity Name. On TableView I needed to bind content and selection indexes to NSArrayController.

如何将NSTreeController绑定到SourceList，当选择子项时，从项目到描述显示另一个ToMany关系。

How can I bind NSTreeController to SourceList and when children is selected, show another ToMany relation from Item to Description.

推荐答案

我可以想出两个解决方案，也许有更好的解决方案。

I can think of two solutions and maybe there is a better one.

解决方案1：
创建NSTreeController的子类并覆盖

Solution 1: Create a subclass of NSTreeController and override

- (NSString *)childrenKeyPathForNode:(NSTreeNode *)node

托管对象 node.representedObject 。

解决方案2：
创建NSManagedObject子类并实现一个 children 子关系。

- (NSSet *)children {
    return self.itemsInGroup;
}

将树控制器的childrenKeyPath设置为children。

Set childrenKeyPath of the tree controller to 'children'.

我认为解决方案2感觉错误，托管对象不应该包含视图的代码，但是如果你已经有NSManagedObject子类，它很容易实现。

I think solution 2 feels wrong, managed objects shouldn't contain code for views, but it is very easy to implement if you already have NSManagedObject subclasses.

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