绑定+ ComBoBox选择问题 [英] Binding + ComBoBox Selection Issue

问题描述

LoadIDs函数将IDComboBox控件绑定到TestDataTable.
LoadName函数将NameTextBox绑定到NameDataTable

Hi,

The LoadIDs function binds the IDComboBox control to the TestDataTable.
The LoadName function binds the NameTextBox to the NameDataTable

应根据IDComboBox中的用户选择填充NameTextBox.

The NameTextBox should be populated based on the user selection from IDComboBox.

但是，绑定IDComboBox时，它将使用第一个值作为IDComboBox.SelectedText，而不是"Select".并立即调用LoadName().

However, when IDComboBox is binding it uses the first value as IDComboBox.SelectedText rather than "Select". And it immediately calls LoadName().

这是为什么?以及如何确保仅当用户选择有效项时才调用LoadName()?
.

Why is this? And how do I ensure that LoadName() is called only when the user selects a valid item?
Thanks.

        private void LoadIDs()
        {
            // get  ids
            ListFrm.LoadID(thisID);

            IDComboBox.DataSource = null;
            IDComboBox.DataSource = ListFrm.TestDataTable;
            IDComboBox.DisplayMember = "Test";
            IDComboBox.ValueMember = "TestID";

            IDComboBox.Text = "Select";
        }

        private void IDComboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (IDComboBox.SelectedText != "Select")
            {
                LoadName();
            }
        }

        private void LoadName()
        {
            ListFrm.LoadName(IDComboBox.Text);

            NameTextBox.DataBindings.Clear();
            NameTextBox.DataBindings.Add("Text", ListFrm.NameDataTable, "Name"); 
        }

推荐答案

我的建议是
您应该在数据表中添加选择"行.并将其插入到DataTable的顶部，然后再将其绑定到ComboBox.
或者，您可以修改

My suggestion is that
You should add a row to the DataTable with "Select" and insert it at the top of the DataTable before binding it to the ComboBox.
Alternatively you can modify the

  if
 (IDComboBox.SelectedText != "Select"
)

            {

                LoadName();

            }

  if condition

Change it to 

  if
 (IDComboBox.Text != "Select"
)

            {

                LoadName();

            }

另外，我猜您正在对ComboBox使用DropDown样式.如果将其设置为DropDownList，则将无法将文本"设置为选择".

Also i guess you are using DropDown style to the ComboBox. If you set it to DropDownList then you will not be able to set the Text to "Select".

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