Question

我有四个文本框，我需要检查空值。如果任何文本框值具有空值，则在按钮单击时，我需要显示“请输入值”之类的提醒。

如果文本框值为空，则此代码将禁用。

ASPX：

<tr style="height: 40px;">
        <td>
            <asp:textbox id="txt1" runat="server">
            </asp:textbox>
        </td>
        <td>
            <asp:textbox id="txt2" runat="server">
            </asp:textbox>
        </td>
        <td>
            <asp:textbox id="txt3" runat="server">
            </asp:textbox>
        </td>
</tr>

<tr>
<td>
<asp:button id="Button1" runat="server" text="Add" cssclass="button" width="50px"
onclick="Button1_Click" /></td>
</tr>

CS：

protected void Button1_Click(object sender, EventArgs e)
{
    if (String.IsNullOrWhiteSpace(txt1.Text) || String.IsNullOrWhiteSpace(txt2.Text) || String.IsNullOrWhiteSpace(txt3.Text))
    {
        string message = "Textbox can be empty, please enter a value";
        string script = String.Format("alert('{0}');", message);
        this.Page.ClientScript.RegisterStartupScript(this.Page.GetType(), "msgbox", script, true);
    }

    if (txt1.Text != "" && txt2.Text != "" && txt3.Text != "" && ddlcategory.Text != "--Select--")
    {
        DataSet ds = new DataSet();
        using (SqlConnection connection = new SqlConnection(str))
        {
            SqlCommand command = new SqlCommand();
            command.Connection = connection;
            string strquery = "select * from product where code='Metal' and Id='" + txt1.Text + "'";
            SqlCommand cmd = new SqlCommand(strquery, connection);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
        }
        if (ds.Tables[0].Rows.Count > 0)
        {
             ClientScript.RegisterStartupScript(this.GetType(),"Key", "<script type='text/javascript'>window.onload = function(){alert('Product Already Exists.');return false;}</script>");                        
        }
        else
        {
            SqlConnection conn = new SqlConnection(str);
            conn.Open();
            SqlCommand cmd = new SqlCommand("Products", conn);
            cmd.Parameters.Add("@id", SqlDbType.VarChar, 30).Value = txt1.Text;
            cmd.Parameters.Add("@name", SqlDbType.VarChar, 50).Value = txt2.Text;
            cmd.Parameters.Add("@email", SqlDbType.VarChar, 30).Value = txt3.Text;
            cmd.Parameters.Add("@category", SqlDbType.VarChar, 20).Value = ddlcategory.Text;
            cmd.Parameters.Add("@id", SqlDbType.Int).Value = 1;
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.ExecuteNonQuery();
            conn.Close();
            conn.Dispose();
            ClientScript.RegisterStartupScript(this.GetType(), "Key", "<script type='text/javascript'>window.onload = function(){alert('Product Created Successfully.');return false;}</script>");               
        }
    }              
}

任何人都建议我这个。

Answer 1

尝试以下

if (String.IsNullOrWhiteSpace(txt1.Text) || String.IsNullOrWhiteSpace(txt2.Text) || String.IsNullOrWhiteSpace(txt3.Text) || String.IsNullOrWhiteSpace(txt4.Text))
{
    string message = "Please enter values";
    string script = String.Format("alert('{0}');", message);
    this.Page.ClientScript.RegisterStartupScript(this.Page.GetType(), "msgbox", script, true);
    return;
}

Answer 2

您可以使用JavaScript代码在客户端执行此操作

function verifyValues()
{
    var txtBox1,txtBox2,txtBox3,txtBox4;
    txtBox1=document.getElementByID("<%= myTextBox1.ClientID %>"):
    txtBox2=document.getElementByID("<%= myTextBox2.ClientID %>"):
    txtBox3=document.getElementByID("<%= myTextBox3.ClientID %>"):
    txtBox4=document.getElementByID("<%= myTextBox4.ClientID %>"):

    if(txtBox1.value=="" || txtBox2.value==""||txtBox3.value=="" 
                         || txtBox4.value=="")
     {
      alert("Please enter any one of the value");
      return false;
     }
    return true;
}

然后你的服务器端标记应该用return语句

调用javascript函数

<asp:Button ID="btnSubmit" runat="server" OnClientClick="return verifyValues();" 
       Text="Click" />

如果要同时检查客户端和服务器端，请在服务器端验证中包含@Damith应答

Answer 3

我会改用 string.IsNullOrEmpty（），然后执行以下操作。

if (string.IsNullOrEmpty(txt1.Text)) {
   ScriptManager.RegisterStartupScript(this.Page, this.Page.GetType(), 
          "err_msg", 
          "alert('Please enter values!)');",
          true);
}

Answer 4

尝试此操作而不是代码，并应在显示警告消息后添加return false

if (string.IsNullOrEmpty(txt1.Text) ||string.IsNullOrEmpty( txt2.Text) || string.IsNullOrEmpty(txt3.Text) || string.IsNullOrEmpty(txt4.Text))
    {
       string script = "<script type=\"text/javascript\">alert('Please enter values');</script>";
       ClientScript.RegisterClientScriptBlock(this.GetType(), "Alert", script);
       Button1.Enabled = false;
        return false;
    }
    else
    {
        Button1.Enabled = true;
    }


}

或

if (string.IsNullOrEmpty(txt1.Text) ||string.IsNullOrEmpty( txt2.Text) || string.IsNullOrEmpty(txt3.Text) || string.IsNullOrEmpty(txt4.Text))
        {
         string script = "alert('Please enter values');";
         ClientScript.RegisterClientScriptBlock(this.GetType(), "Alert", script, true);
           Button1.Enabled = false;
            return false;
        }
        else
        {
            Button1.Enabled = true;
        }


    }

Answer 5

试试这个

if (txt1.Text == "" || txt2.Text == "" || txt3.Text == "" || txt4.Text == "")
        {
           ScriptManager.RegisterStartupScript(this.Page, typeof(Page), "scrip1", "alert('Enter All fields');", true);
        Button1.Enabled = false;
        }
        else
        {
            Button1.Enabled = true;
        }

Answer 6

在所有文本框上应用必填字段验证并为所有文本框提供组名称，对于单击哪个验证应该有效的按钮，所有文本框和按钮的组名称应相同。

Answer 7

这正是您正在寻找的:(多控制的服务器端验证）

http://www.codeproject.com/Tips/722385/Single-Server-Side-Validator-for-Multiple-Controls

Answer 8

您必须在客户端进行此验证，以提高您的性能

如下

function verifyValues()
{
    var txtBox1,txtBox2,txtBox3,txtBox4;
    txtBox1=document.getElementByID("txt2"):
    txtBox2=document.getElementByID("txt2"):
    txtBox3=document.getElementByID("txt2"):
    txtBox4=document.getElementByID("txt2"):

    if(txtBox1.value=="" || txtBox2.value==""||txtBox3.value=="" 
                         || txtBox4.value=="")
     {
      alert("Please enter any one of the value");
      return false;
     }
    return true;
}

单击按钮时发出警报

8 个答案: