将标签和值绑定到 ComboBox Winforms

发布于 2024-09-24 19:02:14 字数 614 浏览 3 评论 0原文

我有这个代码

Public Sub FillCategoryCombobox(ByVal categoryList As List(Of tblCategory), ByVal LvName As ComboBox)
    LvName.Items.Clear()
    Dim itemValue = New Dictionary(Of Integer, String)()
    For Each category As tblCategory In categoryList
        itemValue.Add(category.CategoryID, category.CategoryName)
    Next category
    LvName.DataSource = New BindingSource(itemValue, Nothing)
    LvName.DisplayMember = "Value"
    LvName.ValueMember = "Key"
End Sub

，我收到一个关于

LvName.DataSource = New BindingSource(itemValue, Nothing)

值不能为空的错误

原文

I have this code

Public Sub FillCategoryCombobox(ByVal categoryList As List(Of tblCategory), ByVal LvName As ComboBox)
    LvName.Items.Clear()
    Dim itemValue = New Dictionary(Of Integer, String)()
    For Each category As tblCategory In categoryList
        itemValue.Add(category.CategoryID, category.CategoryName)
    Next category
    LvName.DataSource = New BindingSource(itemValue, Nothing)
    LvName.DisplayMember = "Value"
    LvName.ValueMember = "Key"
End Sub

I receive an error on

LvName.DataSource = New BindingSource(itemValue, Nothing)

Value cannot be null

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悟红尘 2024-10-01 19:02:14

您可以使用字典的 ToList() 方法将字典绑定到数据源。

编辑

一些代码：

LvName.DataSource = itemValue.ToList()
LvName.DisplayMember = "Value"
LvName.ValueMember = "Key"

You can bind a dictionary to a datasource by using the ToList() method of the dictionary.

Edit

Some code:

LvName.DataSource = itemValue.ToList()
LvName.DisplayMember = "Value"
LvName.ValueMember = "Key"

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不知在何时 2024-10-01 19:02:14

从未尝试过将字典绑定到控件的数据源或绑定源。
也许那是不可能的。
为什么不使用你的categoryList作为数据源（用于BindingSource或直接）

combo1.DataSource = categoryList
combo1.DisplayMember = "CategoryName"
combo1.ValueMember = "CategoryID"

或者如果你需要维护位置：

dim bs as new BindingSource(categoryList, nothing)
combo1.DataSource = bs
combo1.DisplayMember = "CategoryName"
combo1.ValueMember = "CategoryID"

或者创建一个List（of Category）而不是字典。

顺便提一句。完整的堆栈跟踪总是有帮助的。

Never ever tried to bind a dictionary to a control's datasource or bindingsource.
Maybe that's not possible.
Why don't you use your categoryList as a DataSource (for the BindingSource or directly)

combo1.DataSource = categoryList
combo1.DisplayMember = "CategoryName"
combo1.ValueMember = "CategoryID"

or if you need to maintain the position:

dim bs as new BindingSource(categoryList, nothing)
combo1.DataSource = bs
combo1.DisplayMember = "CategoryName"
combo1.ValueMember = "CategoryID"

or create a List(of category) instead of a Dictionary.

btw. a full stack trace is always helpfull.

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猫性小仙女 2024-10-01 19:02:14

您需要 BindingSource 吗？如果没有，您可以直接将 ComboBox DataSource 设置为您的列表。您可以使用更简单的东西，例如 KeyValuePair，而不是使用字典。
您可以尝试以下操作：

KeyValuePair[] pairs = new KeyValuePair[0];
ComboBox box = new ComboBox();
box.DisplayMember = "Value";
box.ValueMember = "Key";
box.DataSource = pairs;

Do you need the BindingSource? If not you can set the ComboBox DataSource to your list directly. And instead of using a dictionary you can use something simpler like a KeyValuePair.
Can you try the following:

KeyValuePair[] pairs = new KeyValuePair[0];
ComboBox box = new ComboBox();
box.DisplayMember = "Value";
box.ValueMember = "Key";
box.DataSource = pairs;

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