在IB的值绑定模型密钥路径中使用KVC运算符，例如@ unionOfSets/@ sum [英] Using KVC operator e.g., @unionOfSets/@sum in IB's Value Binding Model Key Path

问题描述

我不确定是否可以这样做-看起来应该很简单，但是我不断收到实体Sale不符合密钥"@sum"的键值编码要求."

I am not sure if this can be done -- it looks like it should be a straightforward thing but I keep getting "the entity Sale is not key value coding-compliant for the key "@sum"."

我对表列值绑定使用"@ unionsOfSets.departments.@ sale.amount".我做对了，或者做对的正确方法是什么?

I using "@[e-mail]" for the Table column value binding. I am doing it right, or what is the right way to do this?

推荐答案

首先，再看看KVC编程指南的.KVC的set和array运算符功能强大，但是很容易弄错它们，即使您已经摸索了该系统.除非您这样做，否则几乎不可能使它们正确.

First, take an other look at the KVC Programming Guide's Set and Array Operators section. KVC's set and array operators are powerful, but it's easy to get them wrong, even after you've grokked the system. And it's nearly impossible to get them right until you do.

也就是说，我认为您的意思是您使用了"@ unionOfSets.departments.@ sum.amount" ，因为您说错误涉及到 @sum 和@sale 不是合法的KVC运营商.假设这是正确的，并且您具有foo-> * departments-> * sales.amount之类的模型，则可能需要类似

That said, I think you mean you used "@[e-mail]" since you say the error involves @sum, and @sale isn't a legal KVC operator. Assuming that's right, and that you have a model like foo->*departments->*sales.amount, you probably want something like

"@[e-mail]"

获取所有部门的总销售额.

to get the total sales for all departments.

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