如何在 asp.net C# 的 OnClick 事件中使用 Page_OnLoad 方法的局部变量

Question

我正在设计一个网站，我需要通过 CompanyDetails 页面更新数据库中的 table 公司，该页面涉及自动递增字段 CompanyID，该字段通过上一页名为 Company 的查询字符串传递，并且只有一个按钮用于插入和更新。所以我的问题是我无法在 SaveButtonClick 事件中获取 Page_OnLoad 事件的 Companyid 值。

注意：我已经尝试过 Session 和 View 状态 IsPostBack，但在 Onclick 事件中甚至它们的值都没有被维护并且被更新为 0 或 null。

这是我的代码......（请忽略我的编码错误）

using System;
using System.Web.UI;
using System.Data;
using System.Data.SqlClient;

public partial class CompanyDetails : System.Web.UI.Page
{
    int Companyid = 0;
    string cmdName = null;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Companyid = Convert.ToInt32(Request.QueryString["CompanyID"]);
            cmdName = Request.QueryString["CommandType"];
            Session["something"] = Companyid;
        }
            if (cmdName == "Details")
            {
                BindTextBoxvalues();
            }
    }

    protected void SaveButton_Click(object sender, EventArgs e)
    {
        string x = Session["something"].ToString();
        try
        {
            if (SaveButton.Text == "Save")
            {
                SqlCommand cmd = new SqlCommand();
                String mycon = "Data Source=.; Initial Catalog=something; Integrated Security=True";
                SqlConnection con = new SqlConnection(mycon);
                cmd = new SqlCommand("spInsertCompany", con);
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.Parameters.Add("@CompanyName", SqlDbType.VarChar).Value = Name.Text;
                cmd.Parameters.Add("@CompanyCode", SqlDbType.VarChar).Value = CompanyCode.Text;
                cmd.Parameters.Add("@LegalName", SqlDbType.VarChar).Value = LegalName.Text;
                cmd.Parameters.Add("@TaxID", SqlDbType.Int).Value = TaxID.Text;
                cmd.Parameters.Add("@BusinessPhone", SqlDbType.VarChar).Value = BusinessPhone.Text;
                cmd.Parameters.Add("@Extension", SqlDbType.VarChar).Value = Extension.Text;
                cmd.Parameters.Add("@FaxNumber", SqlDbType.VarChar).Value = FaxNumber.Text;
                cmd.Parameters.Add("@Description", SqlDbType.VarChar).Value = Description.Value;
                bool isstatus = IsActiveCheckBox.Checked;
                cmd.Parameters.Add("@Status", SqlDbType.Int).Value = Convert.ToInt32(isstatus);
                con.Open();
                cmd.Connection = con;
                cmd.ExecuteNonQuery();
                Response.Write("<script language='javascript'>window.alert('Saved Successfully.');window.location='Company.aspx';</script>");
            }
            else if (SaveButton.Text == "Update")
            {
                SqlCommand cmd = new SqlCommand();
                String mycon = "Data Source=.; Initial Catalog=something; Integrated Security=True";
                SqlConnection con = new SqlConnection(mycon);
                con.Open();
                cmd = new SqlCommand("spUpdateCompany", con);
                cmd.CommandType = CommandType.StoredProcedure;
                int a = Convert.ToInt32(Companyid);
              // I need the value here but it is being updated to zero here.
                cmd.Parameters.Add("@CompanyID", SqlDbType.Int).Value = Companyid;
                cmd.Parameters.Add("@CompanyName", SqlDbType.VarChar).Value = Name.Text;
                cmd.Parameters.Add("@CompanyCode", SqlDbType.VarChar).Value = CompanyCode.Text;
                cmd.Parameters.Add("@BusinessPhone", SqlDbType.VarChar).Value = BusinessPhone.Text;
                cmd.Parameters.Add("@Extension", SqlDbType.VarChar).Value = Extension.Text;
                cmd.Parameters.Add("@FaxNumber", SqlDbType.VarChar).Value = FaxNumber.Text;
                cmd.Parameters.Add("@TaxID", SqlDbType.Int).Value = TaxID.Text;
                cmd.Parameters.Add("@LegalName", SqlDbType.VarChar).Value = LegalName.Text;
                cmd.ExecuteNonQuery();
                cmd.Dispose();
                con.Close();
                Response.Write("<script language='javascript'>window.alert('Updated Successfully.');window.location='Company.aspx';</script>");
            }
        }
        catch (SqlException ex)
        {
            ScriptManager.RegisterStartupScript(this, this.GetType(), "Message",
                "alert('Oops!! following error occured : " + ex.Message.ToString() + "');", true);
        }

    }
    protected void CancelButton_Click(object sender, EventArgs e)
    {
        Response.Redirect("Company.aspx");
    }
    private void BindTextBoxvalues()
    {
        SaveButton.Text = "Update";
        string constr = "Data Source=.; Initial Catalog=something; Integrated Security=True";
        SqlConnection con = new SqlConnection(constr);
        SqlCommand cmd = new SqlCommand("select * from Company where CompanyID=" + Companyid, con);
        DataTable dt = new DataTable();
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        da.Fill(dt);
        Name.Text = dt.Rows[0][1].ToString();
        CompanyCode.Text = dt.Rows[0][2].ToString();
        LegalName.Text = dt.Rows[0][15].ToString();
        TaxID.Text = dt.Rows[0][14].ToString();
        BusinessPhone.Text = dt.Rows[0][3].ToString();
        Extension.Text = dt.Rows[0][13].ToString();
        FaxNumber.Text = dt.Rows[0][12].ToString();
        Description.Value = dt.Rows[0][4].ToString();
        IsActiveCheckBox.Checked = Convert.ToBoolean(dt.Rows[0][11]);
    }
}

Answer 1

如果您希望属性在 PostBack 上可用，请不要使用 !IsPostBack

protected void Page_Load(object sender, EventArgs e)
    {
        Companyid = Convert.ToInt32(Request.QueryString["CompanyID"]);
    }

Answer 2

存储在局部变量中的任何值都需要在每次回发时从请求中读取。

跟随

int Companyid = 0;
string cmdName = null;
protected void Page_Load(object sender, EventArgs e)
{

        Companyid = Convert.ToInt32(Request.QueryString["CompanyID"]);
        cmdName = Request.QueryString["CommandType"];


        if (!IsPostBack)
          {
            if (cmdName == "Details")// be sure about string case
            {
                BindTextBoxvalues();
            }
        }
}

或创建视图状态属性

如何在 asp.net C# 的 OnClick 事件中使用 Page_OnLoad 方法的局部变量

How to use local variable of Page_OnLoad method in OnClick event in asp.net C#

asp.net

onload-event