RadGrid apply filter in codebehind

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C#

ASP.NET

I'm trying to set a value in a filter for RadGrid

protected void gvAnalysisView_OnPreRender(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                if (!String.IsNullOrEmpty(Request.QueryString["SubjectId"]))
                {

                    gvAnalysisView.MasterTableView.IsFilterItemExpanded = true;
                    gvAnalysisView.MasterTableView.FilterExpression = "([SubjectId] = " + subjectId + ")";
                    GridColumn column = gvAnalysisView.MasterTableView.GetColumnSafe("SubjectId");
                    column.CurrentFilterFunction = GridKnownFunction.EqualTo;
                    column.CurrentFilterValue = subjectId;
                    gvAnalysisView.MasterTableView.Rebind();
                }
            }
        }

this Subject Id values changes as per the client selects the subject.
now the thing is i successfully get the output that the filtered grid with the subjectId value.

But the problem is when i clear the value in the filter then the normal gridview that is gridview with no filter has to be obtained.But when i clear the value it is showing nothing?

and i also want to set the width of the gridview from here?


can anyone help me?