更改关联属性（EntityCollection）不会增加PropertyChanged [英] Changing association property (EntityCollection) don't rise PropertyChanged

问题描述

我想通过Converter将只读DataGrid的某些列数据绑定到Entity的Association属性（将集合从此Association属性转换为字符串）。当我尝试从集合中添加/删除元素时，绑定不会触发。物业也已更改，请勿上升。

I want to bind some column data of readonly DataGrid to Association property of Entity through Converter (convert collection from this association property to string). When I try to add/remove elements from collection, binding don't fire. PropertyChanged also, don't rising.

contractPosition.PropertyChanged += (s, e2) =>
    {
           a = 0;//don't fire
    };

contractPosition.ContractToOrderLinks.Remove(link);

这是contractPosition Entity（由EF4生成）的片段：

Here is the fragment of contractPosition Entity (generated by EF4):

[Association("ContractPosition_ContractToOrderLink", "PositionId", "ContractPositionId")]
        [XmlIgnore()]
        public EntityCollection<ContractToOrderLink> ContractToOrderLinks
        {
            get
            {
                if ((this._contractToOrderLinks == null))
                {
                    this._contractToOrderLinks = new EntityCollection<ContractToOrderLink>(this, "ContractToOrderLinks", this.FilterContractToOrderLinks, this.AttachContractToOrderLinks, this.DetachContractToOrderLinks);
                }
                return this._contractToOrderLinks;
            }
        }

为什么PropertyChanged不增加？如何实现绑定刷新？

Why PropertyChanged don't rise? How can I implement binding refresh?

推荐答案

有一些不同的事件需要听：

There are a few different events to listen to:

1. INotifyPropertyChanged.PropertyChanged

当 _contractToOrderLinks 更改。在示例代码中，值从不发生变化，事件被调用从不，并且事件从不被触发。

Fires when the value of _contractToOrderLinks changes. In your sample code, the value never changes, the event is never called, and the event never fires.

INotifyCollectionChanged.CollectionChanged

在添加对象时触发

EntityCollection<> .EntityAdded

添加对象时触发。

EntityCollection< > .EntityRemoved

在删除对象时触发。 我不确定清除集合后是否会为每个实体触发该事件。

Fires when an object is removed. I am not sure if this fires for each entity when the collection is cleared.

我更喜欢使用 INotifyCollectionChanged.CollectionChanged 事件。但是， EntityCollection<> 显式实现该接口，因此必须首先强制转换。试试这个：

I prefer to use the INotifyCollectionChanged.CollectionChanged event. However, EntityCollection<> explicitly implements the interface so you must cast it first. Try this:

((INotifyCollectionChanged)contractPosition.ContractToOrderLinks).CollectionChanged += (s, e) =>
    {
           a = 0; //does fire
    };

contractPosition.ContractToOrderLinks.Remove(link);

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