无法在ComboBox中将SelectedIndex设置为-1 [英] Cannot set SelectedIndex to -1 in ComboBox
问题描述
我已经缩小了一个问题我一直在填充一个组合框，其中
存储的查询结果数据表。我正在将ValueMember和
DisplayMember设置为相关的列名，然后我想确保
没有选择任何内容。
默认情况下，如果你什么也不做，那么第一项（0）就是
被选中。但是，我想将SelectedIndex设置为-1。
如果我有一个独立的窗口它可以工作，但如果我有一个窗口有一个
mdiparent set，它忽略了我将SelectedIndex设置为-1的尝试和
总是选择项目0.
（这里是我的代码...... ）
ComboBox1.DataSource = dt
ComboBox1.ValueMember =" chCountryCode"
ComboBox1.DisplayMember =" chCountryDesc"
ComboBox1.SelectedIndex = -1
我已经尝试过两次设置SelectedIndex = -1，但这并没有解决
它。唯一似乎解决这个问题的是使窗口非childmdi，
但我们的应用程序是一个MDI风格的应用程序！
这是一个错误吗？请问有什么想法吗？
非常感谢，
史蒂夫
Hi,
I''ve narrowed down a problem I''ve been having filling a combobox with the
results of a query stored in a datatable. I''m setting the ValueMember and
DisplayMember to the relevant column names, and then I want to make sure
nothing is selected.
By default it appears that if you do nothing, the first item (0) is
selected. However, I want to set the SelectedIndex to -1.
If I have a standalone window it works, but if I have a window that has an
mdiparent set, it ignores my attempts to set the SelectedIndex to -1 and
always selects item 0.
(here''s my code...)
ComboBox1.DataSource = dt
ComboBox1.ValueMember = "chCountryCode"
ComboBox1.DisplayMember = "chCountryDesc"
ComboBox1.SelectedIndex = -1
I''ve already tried setting SelectedIndex = -1 twice, but that doesn''t fix
it. The only thing that seems to fix it is making the window non-childmdi,
but our application is an MDI style app!
Is this a bug? Any ideas please?
Many thanks,
Steve
推荐答案
" Steve Dyte" < Steve Dy**@discussions.microsoft.com > schrieb：
"Steve Dyte" <Steve Dy**@discussions.microsoft.com> schrieb:
ComboBox1.ValueMember =" chCountryCode"
ComboBox1.DisplayMember =" chCountryDesc"
ComboBox1.SelectedIndex = -1
我'我已经尝试过两次设置SelectedIndex = -1，但这并没有解决它。唯一似乎解决它的问题是使窗口非childmdi，
但我们的应用程序是MDI风格的应用程序！
ComboBox1.ValueMember = "chCountryCode"
ComboBox1.DisplayMember = "chCountryDesc"
ComboBox1.SelectedIndex = -1
I''ve already tried setting SelectedIndex = -1 twice, but that doesn''t fix
it. The only thing that seems to fix it is making the window non-childmdi,
but our application is an MDI style app!
BUG：ComboBox不将SelectedIndex设置为-1时清除
< URL：http：//support.microsoft.com/？scid = kb; EN-US; 327244>
-
Herfried K. Wagner [MVP]
< URL：http：//dotnet.mvps.org/>
BUG: ComboBox Does Not Clear When You Set SelectedIndex to -1
<URL:http://support.microsoft.com/?scid=kb;EN-US;327244>
--
Herfried K. Wagner [MVP]
<URL:http://dotnet.mvps.org/>
" Steve Dyte" < Steve Dy**@discussions.microsoft.com > schrieb：
"Steve Dyte" <Steve Dy**@discussions.microsoft.com> schrieb:
ComboBox1.ValueMember =" chCountryCode"
ComboBox1.DisplayMember =" chCountryDesc"
ComboBox1.SelectedIndex = -1
我'我已经尝试过两次设置SelectedIndex = -1，但这并没有解决它。唯一似乎解决它的问题是使窗口非childmdi，
但我们的应用程序是MDI风格的应用程序！
ComboBox1.ValueMember = "chCountryCode"
ComboBox1.DisplayMember = "chCountryDesc"
ComboBox1.SelectedIndex = -1
I''ve already tried setting SelectedIndex = -1 twice, but that doesn''t fix
it. The only thing that seems to fix it is making the window non-childmdi,
but our application is an MDI style app!
BUG：ComboBox不将SelectedIndex设置为-1时清除
< URL：http：//support.microsoft.com/？scid = kb; EN-US; 327244>
-
Herfried K. Wagner [MVP]
< URL：http：//dotnet.mvps.org/>
BUG: ComboBox Does Not Clear When You Set SelectedIndex to -1
<URL:http://support.microsoft.com/?scid=kb;EN-US;327244>
--
Herfried K. Wagner [MVP]
<URL:http://dotnet.mvps.org/>
我担心这不能解决问题。我已经看过这个bug了。并且
尝试了解决方法。它说它影响了Framework的1.0版，
而我们在v1.1上。
如果我创建一个普通的窗口，它工作正常。只有当我的窗口是MDIParent的一个
子窗口时，它才会忽略我设置SelectedIndex的尝试
= -1。
您应该能够轻松地重新创建这个...
创建一个包含两个MenuItems的表单...
Private Sub MenuItem1_Click（ByVal sender As System.Object，ByVal e As
System.EventArgs）处理MenuItem1.Click
''如果我这样做它将忽略我的SelectedIndex = -1并将其设置为0
Dim x As New Form2
x.MdiParent = Me
x.Show （）
End Sub
Private Sub MenuItem2_Click（ByVal sender As System.Object，ByVal e As
System.EventArgs）处理MenuItem2.Click
''如果我这样做，它将设置SelectedIndex = -1没有问题!!
Dim x As New Form2
x.Show（）
End Sub
仅供参考，Form2是我的测试表格。它有一个组合框，并且表格中的代码加载
来获取DataTable，将其绑定到组合框并尝试设置SelectedIndex
= -1（参见我的原创帖子）
谢谢，
Steve
" Herfried K. Wagner [MVP]"写道：
Hi, I''m afraid this doesn''t fix the problem. I''d already seen this "bug" and
tried the workarounds. It says it affects version 1.0 of the Framework,
whereas we''re on v1.1.
If I create a plain window, it works fine. It''s only when my window is a
child window of an MDIParent that it ignores my attemps to set SelectedIndex
= -1.
You should be able to recreate this fairly easily...
Create a form with two MenuItems on it...
Private Sub MenuItem1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MenuItem1.Click
'' if I do this it will ignore my SelectedIndex = -1 and set it to 0
Dim x As New Form2
x.MdiParent = Me
x.Show()
End Sub
Private Sub MenuItem2_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MenuItem2.Click
'' if I do this, it will set SelectedIndex = -1 with no problems!!
Dim x As New Form2
x.Show()
End Sub
FYI, Form2 is my test form. It has one combobox, and code in the form load
to get a DataTable, bind it to the combobox and try to set the SelectedIndex
= -1 (see my original post)
Thanks,
Steve
"Herfried K. Wagner [MVP]" wrote:
" Steve Dyte" < Steve Dy**@discussions.microsoft.com > schrieb：
"Steve Dyte" <Steve Dy**@discussions.microsoft.com> schrieb:
ComboBox1.ValueMember =" chCountryCode"
ComboBox1.DisplayMember =" chCountryDesc"
ComboBox1.SelectedIndex = -1
我'我已经尝试过两次设置SelectedIndex = -1，但这并没有解决它。唯一似乎解决它的是使窗口非childmdi，
但我们的应用程序是一个MDI风格的应用程序！
ComboBox1.ValueMember = "chCountryCode"
ComboBox1.DisplayMember = "chCountryDesc"
ComboBox1.SelectedIndex = -1
I''ve already tried setting SelectedIndex = -1 twice, but that doesn''t fix
it. The only thing that seems to fix it is making the window non-childmdi,
but our application is an MDI style app!
BUG：ComboBox在您设置时不会清除SelectedIndex为-1
< URL：http：//support.microsoft.com/？scid = kb; EN-US; 327244>
-
Herfried K. Wagner [MVP]
< URL：http：//dotnet.mvps.org/>
BUG: ComboBox Does Not Clear When You Set SelectedIndex to -1
<URL:http://support.microsoft.com/?scid=kb;EN-US;327244>
--
Herfried K. Wagner [MVP]
<URL:http://dotnet.mvps.org/>
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