将一组对象绑定到DataGridView中的ComboboxColumn [英] Binding a collection of objects to a ComboboxColumn in a DataGridView

问题描述

我有一个GUI，允许用户选择一个报告来查看/编辑。当用户选择报告时，它显示报表中的项目。该项目具有许多属性 - 其中大多数属性正确绑定。其中一个属性是Owner，这绑定到一个ComboBoxColumn。

• 报告
  
  
  < $项目
  
  
  
  • 所有者
  
  
  
  

我已经做了非常类似的几次，没有问题，当我设置 DataPropertyName ， DataSource ， ValueMember 和 DisplayMember 。唯一的区别是，这次，而不是项目类型有一个 OwnderID 它实际上有一个所有者对象。

我在另一篇文章中看到了一个建议，通过给列表中的项目提供一个自我来解决这个问题 - 引用属性，允许他们返回自己的目的设置 ValueMember

但是，当我绑定它这样：

  OwnerColumn.DataPropertyName =Owner
 OwnerColumn.DataSource = ownersBindingSource1 
 OwnerColumn.ValueMember =Self
 OwnerColumn.DisplayMember =OwnerName
  

我收到很多错误如：

 无法将类型为System.String的对象转换为键入Owner。 
  

和：

 code> DataGridView中发生以下异常：
 
 System.ArgumentException：DataGridViewComboBoxCell值无效。 
 
要替换此默认对话框，请处理DataError事件。 
  

我可以通过这样绑定来解决这些错误：

  OwnerColumn.DataPropertyName =Owner
 OwnerColumn.DataSource = ownersBindingSource1 
  

，还可以在所有者上创建 ToString 显示 OwnerName 属性。这似乎很奇怪，但是我认为我误解了一些根本的事情，因为它仍然无法正常运作。任何帮助将不胜感激。

解决方案

我发现很多错误来自我对各种文章的误解已经阅读了，以及乱码。

我忽略了在一些属性上指定返回类型，选项显式/选项严格都关闭，并且有在我的设计师中有一些腐败，一些列被重复。

我最喜欢的一个解决方案是： http://code.google.com/p/systembusinessobjects/source/ browse / trunk / System.BusinessObjects.Framework / Data / SafeBindingLists.cs 。不幸的是，这需要Castle代理和旧版NHibernate。

这是我找到的简单解决方案：

问题是您无法将列表与多种类型的对象绑定。目标是使ComboBox能够直接将属性的值设置为与另一个对象绑定的对象。

我选择使用View对象，并绑定到该列表。

查看对象：

 公共类OwnerView 
私有_所有者作为所有者
 
公共ReadOnly属性OwnerId As Integer 
获取
返回_owner.OwnerId 
结束获取
结束属性
 
公开ReadOnly属性OwnerName As String 
获取
返回_owner.OwnerName 
结束获取
结束属性
 
公共ReadOnly属性所有者缩写As String 
获取
返回_owner.OwnerAbbreviation 
结束获取
结束属性
 
公共可覆盖ReadOnly属性自己作为所有者
获取
返回_owner 
结束获取
结束属性
 
公共子N ew（ByVal owner As Owner）
 _owner = owner 
 End Sub 
 
结束类
  

绑定：

  With OwnerColumn 
 .SortMode = DataGridViewColumnSortMode.Automatic 
 .ReadOnly = False 
 .Name =OwnerColumn
 .HeaderText =Owner
 
 Dim bs As New BindingSource（）
 
对于每个co作为所有者的所有者
 bs.Add（新OwnerView（co））
下一个
 
 .DataPropertyName =所有者
 .DataSource = bs 
 .ValueMember =Self
 .DisplayMember =OwnerName
 
 ItemDataGridView.Columns.Add（OwnerColumn）
结束
  / pre> 
I have a GUI which allows the user to select a report to view/edit. When the user selects a report, it shows the Items in the report. The Item has many properties - most of which are binding properly. One of the properties is Owner, and this is bound to a ComboBoxColumn.


Report

Items

Owner




I have done something very similar to this a few times and had no problems when I set the DataPropertyName, DataSource, ValueMember, and DisplayMember. The only difference is that this time instead of the Item type having an OwnderID it actually has an instance of the Owner object.

I saw a suggestion on another post to solve this issue by giving the items bound in the list a self-referencing property that allows them to return themselves for the purposes of setting the ValueMember

However, When I bind it this way:
OwnerColumn.DataPropertyName = "Owner"
OwnerColumn.DataSource = ownersBindingSource1
OwnerColumn.ValueMember = "Self"
OwnerColumn.DisplayMember = "OwnerName"
I get a lot of errors like: 
Unable to cast object of type 'System.String' to type 'Owner'.
and:
The following exception occurred in the DataGridView:

System.ArgumentException: DataGridViewComboBoxCell value is not valid.

To replace this default dialog please handle the DataError event.
I was able to get around some of these errors by binding it like this:
OwnerColumn.DataPropertyName = "Owner"
OwnerColumn.DataSource = ownersBindingSource1
and also by making the ToString function on the Owner display the OwnerName property. This seems pretty hacky though - and I think I'm misunderstanding something fundamental as it still does not function properly. Any help would be much appreciated.
解决方案
I found out that a lot of my errors were coming from my misunderstanding of various articles I had read, as well as sloppy code.

I neglected to specify the return type on a few of the properties, option explicit / option strict were both off, and there had been some corruption in my designer and a few of the columns were duplicated.

A solution to this that I liked the most was: http://code.google.com/p/systembusinessobjects/source/browse/trunk/System.BusinessObjects.Framework/Data/SafeBindingLists.cs . Unfortunately, this requires Castle proxy, and an older version of NHibernate.

Here is the simple solution that I found:

The issue is that you cannot bind a list with objects of multiple types. The goal is to be able to have the ComboBox directly set the value of a property on the object it is bound to with another object.

I chose to use a View object, and bind the list to that.

View Object:
Public Class OwnerView
    Private _owner As Owner

    Public ReadOnly Property OwnerId As Integer
        Get
            Return _owner.OwnerId
        End Get
    End Property

    Public ReadOnly Property OwnerName As String
        Get
            Return _owner.OwnerName
        End Get
    End Property

    Public ReadOnly Property OwnerAbbreviation As String
        Get
            Return _owner.OwnerAbbreviation
        End Get
    End Property

    Public Overridable ReadOnly Property Self As Owner
        Get
            Return _owner
        End Get
    End Property

    Public Sub New(ByVal owner As Owner)
        _owner = owner
    End Sub

End Class
Binding:
With OwnerColumn
    .SortMode = DataGridViewColumnSortMode.Automatic
    .ReadOnly = False
    .Name = "OwnerColumn"
    .HeaderText = "Owner"

    Dim bs As New BindingSource()

    For Each co As Owner In Owners
        bs.Add(New OwnerView(co))
    Next

    .DataPropertyName = "Owner"
    .DataSource = bs
    .ValueMember = "Self"
    .DisplayMember = "OwnerName"

    ItemDataGridView.Columns.Add(OwnerColumn)
End With


                        
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