如何从放置在表单上的面板中捕获值

Question

我不明白如何在表单面板中的文本框中捕获值。我正在尝试使用这些值更新我的数据库表。

谁能指出我正确的方向？

代码：

private void btnSupplier_Click(object sender, EventArgs e)
    {
        try
        {
            Panel pnlAddSupplier = new Panel();
            TextBox txtSupplierID = new TextBox();
            TextBox txtSupplierName = new TextBox();
            Button btnAddSupplier = new Button();
            Label lblSupplierID = new Label();
            Label lblSupplierName = new Label();

            // Initialize the Panel control.
            pnlAddSupplier.Location = new Point(56, 74);
            pnlAddSupplier.Size = new Size(200, 200);
            // Set the Borderstyle for the Panel to three-dimensional.
            pnlAddSupplier.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;

            // Initialize the Label and TextBox controls.
            lblSupplierID.Location = new Point(60, 0);
            lblSupplierID.Text = "Supplier ID";
            lblSupplierID.Size = new Size(104, 20);
            txtSupplierID.Location = new Point(20, 40);
            txtSupplierID.Text = "";
            txtSupplierID.Size = new Size(152, 20);

            lblSupplierName.Location = new Point(20, 70);
            lblSupplierName.Text = "Supplier Name";
            lblSupplierName.Size = new Size(150, 20);
            txtSupplierName.Location = new Point(20, 90);
            txtSupplierName.Text = "";
            txtSupplierName.Size = new Size(152, 20);

            lblSupplierID.Location = new Point(16, 16);
            lblSupplierID.Text = "Supplier ID";


            btnAddSupplier.Location = new Point(60, 120);
            btnAddSupplier.Text = "Add";
            btnAddSupplier.Click += btnAddSupplier_Click;
            // Add the Panel control to the form. 
            this.Controls.Add(pnlAddSupplier);
            // Add the Label and TextBox controls to the Panel.
            pnlAddSupplier.Controls.Add(lblSupplierID);
            pnlAddSupplier.Controls.Add(txtSupplierID);
            pnlAddSupplier.Controls.Add(lblSupplierName);
            pnlAddSupplier.Controls.Add(txtSupplierName);
            pnlAddSupplier.Controls.Add(btnAddSupplier);

        }
        catch { }
    }

 public void btnAdd_Click(object sender, EventArgs e)
        {
            string username= //how to assign textbox value?;
            int age = //how to assign textbox value;

            MySql.Data.MySqlClient.MySqlCommand cmd = new MySql.Data.MySqlClient.MySqlCommand();

            string query = "INSERT INTO table(username, age) VALUES ('@xxx', '@xxx') "; 

             //please not these values are for demonstration.

            using (connection)
            {
                  ObjDb.OpenConnection();
                ObjDb.ExecuteNonQuery(query, connection);
            }
        }

如您所见，此代码对 SQL 注入开放，我想使用参数。为此，我需要捕获详细信息输入。如何实现？

我尝试分配 supplierID = txtSupplierID.Text，但收到一条消息说 txtSupplier.Text 不存在。

谢谢。

Answer 1

我不知道哪个文本框用于年龄，但我希望这能给你一个好的起点。

string username = txtSupplierID.Text; // how to assign textbox value?;
int age = Int32.Parse(...); // how to assign textbox value;

您需要对年龄进行更多验证。因此，最好使用：

int age;
if (!Int32.TryParse(..., out age))
{
    MessageBox.Show("Incorrect age!");
    return;
}

将 txtSupplierID 更改为字段：

private TextBox txtSupplierName;

并更新这些行：

txtSupplierName = new TextBox(); // remove TextBox

Answer 2

这是你的意思吗？假设用户将始终在 txtSupplierID TextBox 中输入整数值，这应该可以正常工作。将 Name 属性分配给您的 Control 并通过该 Name 访问它。随意问任何我没有解释的东西。干杯！

private void btnSupplier_Click(object sender, EventArgs e)
{
    Panel pnlAddSupplier = new Panel()
    {
        Name = "pnlAddSupplier",
        Location = new Point(56, 74),
        Size = new Size(200, 200),
        BorderStyle = BorderStyle.Fixed3D
    };
    TextBox txtSupplierID = new TextBox()
    {
        Name = "txtSupplierID",
        Location = new Point(20, 40),
        Text = string.Empty,
        Size = new Size(152, 20)
    };
    TextBox txtSupplierName = new TextBox()
    {
        Name = "txtSupplierName",
        Location = new Point(20, 90),
        Text = string.Empty,
        Size = new Size(152, 20)
    };
    Label lblSupplierID = new Label()
    {
        Name = "lblSupplierID",
        Location = new Point(20, 20),
        Text = "Supplier ID:",
        Size = new Size(104, 20)
    };
    Label lblSupplierName = new Label()
    {
        Name = "lblSupplierName",
        Location = new Point(20, 70),
        Text = "Supplier Name:",
        Size = new Size(150, 20)
    };
    Button btnAddSupplier = new Button()
    {
        Name = "btnAddSupplier",
        Location = new Point(60, 120),
        Text = "Add",
    };
    btnAddSupplier.Click += btnAdd_Click;

    // Add controls to the Panel.
    pnlAddSupplier.Controls.Add(lblSupplierID);
    pnlAddSupplier.Controls.Add(txtSupplierID);
    pnlAddSupplier.Controls.Add(lblSupplierName);
    pnlAddSupplier.Controls.Add(txtSupplierName);
    pnlAddSupplier.Controls.Add(btnAddSupplier);

    // Add the Panel control to the form. 
    this.Controls.Add(pnlAddSupplier);
}

public void btnAdd_Click(object sender, EventArgs e)
{
    string username = this.Controls["pnlAddSupplier"].Controls["txtSupplierName"].Text;
    int age = Int32.Parse(this.Controls["pnlAddSupplier"].Controls["txtSupplierID"].Text);

    MySql.Data.MySqlClient.MySqlCommand cmd = new MySql.Data.MySqlClient.MySqlCommand();

    string query = "INSERT INTO table(username, age) VALUES ('@xxx', '@xxx') ";

    using (connection)
    {
        ObjDb.OpenConnection();
        ObjDb.ExecuteNonQuery(query, connection);
    }
}

Answer 3

首先，您需要为控件命名：

 txtSupplierID.Name = "txtSupplierID";

然后你可以得到这样的值：

Control[] Found = this.Controls.Find("txtSupplierID", true);

TextBox IDTextBox = Found[0] as TextBox;

string SupplierID = IDTextBox.Text;

别忘了添加错误检查！

Answer 4

您正在使您的供应商 ID 文本框成为您的 btnSupplier_Click 函数的局部变量。您需要将其设为类变量。如果您使用设计器将它拖放到您的网页上，那么这个变量应该出现在您的 *.designer.cs 文件中。

以下是如何使用参数来防止 SQL 注入：

            DbCommand myCommand = Connection.CreateCommand();
            myCommand.CommandText = @"select * from myTable mt
                where 
                mt.paramter = @myParameter";

            DbParameter myParameter = myCommand.CreateParameter();
            myParameter.ParameterName = "@myParameter";
            myCommand.Parameters.Add(myParameter);