RegisterForEventValidation can only be called during Render();

 

 

When we export gridview data to excel,word,notepad and csv using asp.net  we found this type of error :

 

 

This error occurs whenever we are trying to render control to response. To solve this problem I have added EnableEventValidation="false" to @Page directive of aspx page that should be just like this 

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ExportGridviewtoExcel.aspx.cs" Inherits="ExportGridviewtoExcel" EnableEventValidation="false"%>

By Setting EnableEventValidation="false" property to @Page directive of aspx page the problem has solved automatically.

 

 

Second problem in export to excel is  :

 

  "Control 'GridView1' of type 'GridView' must be placed inside a form tag with runat=server."

 

 

Add this code in server side :

 

 

public override void VerifyRenderingInServerForm(Control control)
    {
        //It solves the error "Control 'GridView1' of type 'GridView' must be placed inside a form tag with runat=server."
    } 

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Show hide Grid column using common function

1 To Hide column in perticular range :

public static void showhide(GridView gv,bool flag,int frmindex,int toindex,bool isfixcolhide,string footertext)

    {

        if (isfixcolhide)

        {

            gv.Columns[frmindex].Visible = flag;

            gv.Columns[frmindex + 1].FooterText = footertext;

        }

        else

        {

            for (int i = frmindex; i <= toindex; i++)

            {

                gv.Columns[i].Visible = flag;

            }

            gv.Columns[toindex + 1].FooterText = footertext;

        }

     

    }

Example:

            To hide Grid column from 1 to 11 as below with show footer text in next column :

                             showhide(gvrf, false, 1, 11, false, "total");

1 To Hide perticular columns using array index :

 

       public static  void showhide(GridView gv, bool flag, int[] index)

        {

            for (int i = 0; i <= index.Length; i++)

            {

                gv.Columns[index[0]].Visible = flag;

            }

        }

Example :  To hide column 1 and 3 as below :

                          int[] x = { 1, 3};

                            showhide(gvrf, false, x);

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