最小值的XCode数据模型编辑器中的获取属性 [英] Fetched Property in XCode Data Model Editor for minimum value

问题描述

如何在XCode的数据模型编辑器中为一个属性的最小值添加Fetched属性

How do I add a Fetched Property in XCode's Data Model Editor for minimum value of one attribute??

我的模型：

Item (name, note, storedItem)
StoredItem (price, item)
Item 1 ---> N StoredITem (1->N Relationship)

我想要该项目有一个获取的属性名为minPrice，它的值是为storedItems中的价格设置的最小值。

I want that Item has a fetched property named minPrice and its value is the minimum value setted for price in the storedItems.

示例：

Item1 (banana, storedItem1 ... storedItem4, 10)
StoredItem1 (10,item1)
StoredItem2 (15,item1)
StoredItem3 (30,item1)
StoredItem4 (54,item1)

StoredItem？

What do I put in Destination?? StoredItem?

我在Expression？

And what do I put in Expression??

推荐答案

目标是你想要的实体类型。

The destination is the type of entity you want back.

你想要一个StoredItem回来，因为它有一个价格。

It sounds like you want a StoredItem back, since that has a price on it.

我认为你想要的是一个获取的属性项目名为minPrice，用这个表达式：

What I think you want is a fetched property on Item called minPrice, with this expression:

"@min.storedItems.price"

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