Breeze.js：将元素添加到导航属性集合中而没有反向相关会引发异常[无法获取属性'name'的值] [英] Breeze.js: adding an element to a navigation property collection without inverse rel raises an exception [Unable to get value of the property 'name']
问题描述
我的EDM中有两个实体，分别是 Application 和 Address ，如下所示：
I have two entities in my EDM, Application and Address pretty much like the following:
class Application
{
ICollection<Address> Addresses { get; set; }
}
class Address { }
在客户端上，我为每个实例创建一个实例，并尝试将 address 实例添加到 Application.addresses 集合中：
On the client, I create an instance of each and try to add the address instance to the Application.addresses collection:
var address = addressType.createEntity(...);
var application = applicationType.createEntity(...);
application.addresses.push(address);
不幸的是，我收到一个运行时异常消息： 无法获得属性名称：对象为null或未定义。
Unfortunately, I get a runtime exception saying: "Unable to get value of the property 'name': object is null or undefined".
我将异常追溯到 checkForDups 函数中的 breeze.debug.js@9393-9404 （v1.2.8）：
I tracked the exception back to the checkForDups function in breeze.debug.js@9393-9404 (v1.2.8):
function checkForDups(relationArray, adds) {
// don't allow dups in this array. - also prevents recursion
var inverseProp = relationArray.navigationProperty.inverse;
var goodAdds = adds.filter(function(a) {
if (relationArray._addsInProcess.indexOf(a) >= 0) {
return false;
}
var inverseValue = a.getProperty(inverseProp.name);
return inverseValue != relationArray.parentEntity;
});
return goodAdds;
}
发生这种情况时，我的实体处于一对多的单向关系（没有反向导航属性）；由于在运行时 relationArray.navigationProperty.inverse 是 undefined 的结果，因此尝试访问<$ c时出现错误$ c>名称属性。
As it happens, my entities are in a one-to-many unidirectional relationship (without an inverse navigation property); as a result at runtime relationArray.navigationProperty.inverse is undefined and so the error when trying to access the name property.
添加简单的检查即可解决此问题，并允许将其添加到集合中：
Adding a simple check fixes the problem, and allows adding to the collection:
if (!inverseProp) {
return true;
}
毕竟，问题是：这是bug还是仅仅是从Breeze 1.3开始，
So after all this the question is: is this a bug or is it simply that Breeze does not support one-to-many unidirectional?
推荐答案
编辑表示Breeze不支持一对多单向？ .5，现已发布（2013年6月4日），此问题已修复。
Edit As of v Breeze 1.3.5, available now (June 4 2013), this has been fixed.
编辑：好的，这是一个错误，但是我无法获得当前版本的修复程序。我将尝试在以下版本中获得它。
Ok, this IS a bug, but I couldn't get the fix in for this current release. I will try to get it in the following release.
您建议的修复程序是一个好主意，实际上只是掩盖了问题所在。
The fix that you suggested, which was a good idea, actually only hides the issue.
真正的问题是，对于我们在1-> n方向（即不在n->方向）进行单向导航的情况，微风没有足够的元数据1个方向）。因此，导航集合中的重复实体检查将不起作用，并且也将丢失自动将孩子挂接到父母的功能。
The real problem is that breeze does not have sufficient metadata for the case where we have a unidirectional navigation in the 1->n direction (i.e. not in the n->1 direction). Because of this, duplicate entity checking in the navigation collection will not work and automatic hookup of children to parents will be missing as well.
在获得解决方案之前，最简单的解决方法是简单地使其成为双向导航。请注意，在另一个方向上进行单向导航也可以。
The simplest work around until we get the fix in is to simply make it a bidirectional navigation. Note that unidirectional navigation in the other direction works just fine.
这可能是一个错误
OrderDetails和Products之间的单向导航的DocCode示例项目中的示例。但是在那种情况下，我们允许从OrderDetail-> Product（1-1）导航，而不是从Product-> OrderDetails（1-n）导航。
We do have an example in our DocCode sample project of a unidirectional navigation between OrderDetails and Products. But in that case we allow navigation from a OrderDetail -> Product (1-1) but not from Product -> OrderDetails (1-n).
您的情况似乎相反，即允许1-n但不允许相应的1-1。我将创建一些测试，如果可以对其进行复制，它将在下一版本中修复。
Your case appears to be the opposite, i.e. allowing 1-n but disallowing the corresponding 1-1. I will create some tests and if I can repro this, it will be fixed in the next release.
发生这种情况时，我会在此发布。 （以及查找它的方法：）
I will post back here when that occurs. ( and thx for finding it :)
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