显示 system.data.datarowview 的组合框数据绑定 [英] Combobox databinding showing system.data.datarowview

问题描述

我正在将组合框与数据源、显示成员、值成员绑定.它在我的电脑上工作正常，但在客户端电脑上却无法正常工作.以下是我的源代码:

I am binding combobox with datasource, displaymember, valuemember. It is working fine in my computer but it is not working in clients pc. Following is my source code:

cbxAlloyBinding 方法是从 UserControl 的构造函数调用的.

cbxAlloyBinding method is called from the Constructor of the UserControl.

private void cbxAlloyBinding()
    {
        DataTable dt = new DataTable();
        SqlDataAdapter adp = new SqlDataAdapter("SELECT alloyName,alloyId FROM alloy", con);
        adp.Fill(dt);

        if (dt.Rows.Count > 0)
        {
            cbxMetal.DisplayMember = "alloyName";
            cbxMetal.ValueMember = "alloyId";
            cbxMetal.DataSource = dt;
        }
        else
        {
            cbxMetal.Text = "";
        }
    }

    private void cbxMetal_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (cbxMetal.SelectedIndex != -1)
        {
            DataTable dt = new DataTable();
            tempcmd = new SqlCommand("SELECT specification,alloyCode FROM alloy where alloyId='" + cbxMetal.SelectedValue + "'", con);
            SqlDataAdapter adp = new SqlDataAdapter(tempcmd);
            adp.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                txtSpecification.Text = dt.Rows[0]["alloyCode"].ToString();
                txtSupplyConditions.Text = dt.Rows[0]["specification"].ToString();
                cbxheatBinding();
            }
            else
            {
                txtSpecification.Text = "";
            }

        }
    }

这两天一直困扰着我，我几乎尝试了所有技巧，但仍然无法正常工作.

This is bothering me from last two days and i almost tried all tricks but it is still not working.

客户的 PC 使用的是 Windows 7 Ultimate、sql server 2005 和 .net framework 3.5.

Client's PC is using Windows 7 ultimate, sql server 2005 and .net framework 3.5.

推荐答案

如果在构造函数中调用 cbxAlloyBinding() 之前调用 cbxMetal_SelectedIndexChanged，这肯定会发生.

This definitely happens if your cbxMetal_SelectedIndexChanged is called before cbxAlloyBinding() is called in your constructor.

例如(请参阅下面的代码)，您可能在构造函数中具有其他组合框绑定，它们可能位于构造函数中的 cbxAlloyBinding() 之前，并且这些绑定正在调用 cbxMetal_SelectedIndexChanged.

For instance (see the code below), you may have other combobox bindings in constructor which may come before cbxAlloyBinding() in constructor, and those bindings are calling cbxMetal_SelectedIndexChanged.

public Constructor()
{
        InitializeComponent();

        cbxheatBinding();      //1st Three Binding Methods may be somehow related to your cbxMetal,
        dtpStartDateBinding(); //which leads them to call cbxMetal_SelectedIndexChanged method.
        dtpEndDateBinding();
        cbxAlloyBinding();
}

我怀疑您的 cbxMetal.DataSource 是从代码中的某个其他点设置的，并且早在 DisplayMember 和 ValueMember 被分配之前；

What I suspect is your cbxMetal.DataSource is set from some other point in your code and well before DisplayMember and ValueMember are assigned;

请记住，System.DataRow.DataRowView 仅在

ComboBox.SelectedValue 在 ValueMember 赋值之前被调用.

ComboBox.SelectedValue is called before ValueMember assignment.

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