Question

我有一个简单的问题让我发疯。我试图查询数据实体，一切正常，直到我尝试引用外部的东西。在下面的代码中（完美地工作）我想将.where clientID == 15更改为.where客户端ID是组合框中显示的值，组合框值成员是一个整数：

<root>
  <node>Text</node>
</root>

非常感谢任何简单的帮助。

我正在使用带有C＃和EF6的VS2015社区

Answer 1

首先获取值，将其转换为正确的类型，然后在linq查询中使用该参数：

    private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        int value = (int)comboBox1.SelectedValue;
        using (var context2 = new tvdm())
        {
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new { c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;

        }
    }

Answer 2

我想你需要像

这样的东西

var cus = context2.tblContacts
    .Where(c => c.ClientID == Convert.ToInt32(myComboBox.SelectedItem))
    .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
    .OrderBy(p => p.LastName)
    .ToList();

Answer 3

private void comboBox1_SelectionChangeCommitted(object sender, EventArgs e)
{

ComboBox senderComboBox = (ComboBox) sender;
int selectedValue = (int)senderComboBox.SelectedValue;

// and assuming that there's nothing wrong with this code
using (var context2 = new tvdm())
    {
        var cus = context2.tblContacts
            .Where(c => c.ClientID == selectedValue)
           .Select(c => new { c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
            .OrderBy(p => p.LastName)
            .ToList();

        dataGridView1.DataSource = cus;

    }

}

Answer 4

我实际上最终得到了：

{{1}}

如何使用c＃查询组合框的Linq

4 个答案: