使用ComboBox和Column.Contains实现动态Linq To Sql
使用ComboBox和Column.Contains实现动态Linq To Sql
提问于 2009-06-25 17:19:14
我有一个文本框，组合框，按钮和表单上的DataGridView，用于搜索和返回客户信息从MSSQL视图(vCustomer)。它工作得很好，但我知道我的代码可以更有效率。组合框中的四个项目表示要搜索的列。
有没有一种简单的方法可以将下面的代码转换为动态LINQ to SQL？我是C#的新手。我看了一些其他的帖子，但我似乎不能让它工作。
public partial class MainForm : Form
{
public MainForm()
{
InitializeComponent();
}
private void MainForm_Load(object sender, EventArgs e)
{
// columns to filter for
string[] list = new string[4];
list[0] = "Name";
list[1] = "CustomerAccountNo";
list[2] = "Telephone";
list[3] = "Postal";
// bind to combobox
cboColumn.DataSource = list;
cboColumn.SelectedIndex = 0;
}
private void btnSearch_Click(object sender, EventArgs e)
{
try
{
Cursor.Current = Cursors.WaitCursor;
CustomerSearchDataContext db = new CustomerSearchDataContext();
IEnumerable<vCustomer> customerQuery = null;
switch (cboColumn.SelectedIndex)
{
case 0:
customerQuery = from c in db.vCustomers
where c.Name.Contains(txtSearch.Text)
orderby c.CustomerAccountNo descending
select c;
break;
case 1:
customerQuery = from c in db.vCustomers
where c.Name.Contains(txtSearch.Text)
orderby c.CustomerAccountNo descending
select c;
break;
case 2:
customerQuery = from c in db.vCustomers
where c.Telephone.Contains(txtSearch.Text)
orderby c.CustomerAccountNo descending
select c;
break;
case 3:
customerQuery = from c in db.vCustomers
where c.Postal.Contains(txtSearch.Text)
orderby c.CustomerAccountNo descending
select c;
break;
}
customerBindingSource.DataSource = customerQuery;
dataGridView1.DataSource = customerBindingSource;
dataGridView1.Columns["CustomerId"].Visible = false;
}
catch (System.Data.SqlClient.SqlException ex)
{
MessageBox.Show("An Error Occured - " + ex.Message,"Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
finally
{
Cursor.Current = Cursors.Default;
}
}
}回答 2
Stack Overflow用户
回答已采纳
发布于 2009-06-25 17:42:28
使用[System.Linq.Dynamic][1]。
从方法中获取条件并在单个查询中使用它。
switch (choice)
{
case case1:
condition = string.Format("{0}.Contains({1})", "Column", "Value"
break;Stack Overflow用户
发布于 2009-06-26 14:28:33
嘿，罗尼。我尝试了你的建议，并重构了我的代码(见下文)。但是，我收到一个错误：在类型'vCustomer'中没有属性或字段'smith‘。顺便说一下，MessageBox.Show(condition)；行返回看起来正确的Name.Contains(smith)。
我做错了什么？很抱歉我是个菜鸟，谢谢你的帮助。
弄清楚了..。需要用双引号将搜索字符串括起来！代码已被编辑。
public partial class MainForm : Form
{
public MainForm()
{
InitializeComponent();
}
private void MainForm_Load(object sender, EventArgs e)
{
// data column to filter against
string[] list = new string[4];
list[0] = "Name";
list[1] = "CustomerAccountNo";
list[2] = "Telephone";
list[3] = "Postal";
cboColumn.DataSource = list;
cboColumn.SelectedIndex = 0;
// left, right or middle search
string[] list2 = new string[3];
list2[0] = "Contains";
list2[1] = "StartsWith";
list2[2] = "EndsWith";
cboFilterAtt.DataSource = list2;
cboFilterAtt.SelectedIndex = 0;
}
private void btnSearch_Click(object sender, EventArgs e)
{
try
{
Cursor.Current = Cursors.WaitCursor;
CustomerSearchDataContext db = new CustomerSearchDataContext();
//string condition = string.Format("{0}.{1}({2})", cboColumn.SelectedValue, cboFilterAtt.SelectedValue, txtSearch.Text);
string condition = string.Format("{0}.{1}({2})", cboColumn.SelectedValue, cboFilterAtt.SelectedValue, "\"" + txtSearch.Text + "\"");
MessageBox.Show(condition);
var customerQuery = db.vCustomers.Where(condition).OrderBy("CustomerAccountNo");
customerBindingSource.DataSource = customerQuery;
dataGridView1.DataSource = customerBindingSource;
dataGridView1.Columns["CustomerId"].Visible = false;
}
catch (System.Data.SqlClient.SqlException ex)
{
MessageBox.Show("An Error Occured - " + ex.Message,"Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
finally
{
Cursor.Current = Cursors.Default;
}
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/1045146
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