dynamic gridview

[sds814]

I have a drop down list that fetches the data for the Products or the Order table into a dataset. This dataset gets bounded to a gridview. The data in the gridview has to be editable. I was thinking of dynamically creating itemtemplates w/ textboxes depending on the number of columns in the dataset.

I've been using this link as a reference:

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.templatefield.templatefield.aspx.

But I can't figure out how the InstantiateIn method gets called. After stepping thru the code, the InstantiateIn method runs after the page load even. But again I don't see code that calls this method.

Any help would be appreciated.

This is what I have so far:

public class GridViewTemplate : ITemplate
{
        private DataControlRowType templateType;
        private string columnName;

        public GridViewTemplate(DataControlRowType type, string colName)
        {
            templateType = type;
            columnName = colName;
        }

        public void InstantiateIn(System.Web.UI.Control container)
        {
            switch (templateType)
            {
                case DataControlRowType.Header:
                    Literal lc = new Literal();
                    lc.Text = columnName;
                    container.Controls.Add(lc);
                    break;
                case DataControlRowType.DataRow:
                    TextBox txtMapping = new TextBox();
                    txtMapping.DataBinding += new EventHandler(this.Mapping_DataBinding);
                    container.Controls.Add(txtMapping);
                    break;
                default:
                    break;
            }
        }

        private void Mapping_DataBinding(Object sender, EventArgs e)
        {
            TextBox t = (TextBox)sender;

            GridViewRow row = (GridViewRow)t.NamingContainer;

            t.Text = DataBinder.Eval(row.DataItem, columnName).ToString();
        }
}
    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                LoadGridView();
            }
        }

        private void LoadGridView()
        {
            Database SqlDb = DatabaseFactory.CreateDatabase();

            DataSet dsMappingTable = SqlDb.ExecuteDataSet(CommandType.Text, "SELECT * FROM " + ddlMappingTable.Items[ddlMappingTable.SelectedIndex].Value.ToString());

            gvMappingTable.DataSource = dsMappingTable.Tables[0];
            gvMappingTable.DataBind();

            for (int i = 1; i < dsMappingTable.Tables[0].Columns.Count; i++)
            {
                TemplateField tf = new TemplateField();
                tf.ItemTemplate = new GridViewTemplate(DataControlRowType.DataRow, dsMappingTable.Tables[0].Columns[0].ColumnName);
                tf.HeaderTemplate = new GridViewTemplate(DataControlRowType.Header, dsMappingTable.Tables[0].Columns[0].ColumnName);
                gvMappingTable.Columns.Add(tf);
            }
        }

        protected void ddlMappingTable_SelectedIndexChanged(object sender, EventArgs e)
        {
            LoadGridView();
        }
}

 

[jbenson001]

Why would the number of columns vary?
You should be writing a stored procedure for each scenrio you need and bind the grid to the results. this way you know the columns you will be getting back

 

[sds814]

The columns would have vary among the tables. The scenario I have given is simpler to the one I'm dealing. There are about 12 tables that the user can insert/update data to.

The problem was with the logic in creating a new template and binding the gridview. The above code should've been

            for (int i = 1; i < dsMappingTable.Tables[0].Columns.Count; i++)
            {
                TemplateField tf = new TemplateField();
                tf.ItemTemplate = new GridViewTemplate(DataControlRowType.DataRow, dsMappingTable.Tables[0].Columns[0].ColumnName);
                tf.HeaderTemplate = new GridViewTemplate(DataControlRowType.Header, dsMappingTable.Tables[0].Columns[0].ColumnName);
                gvMappingTable.Columns.Add(tf);
            }

            gvMappingTable.DataSource = dsMappingTable.Tables[0];
            gvMappingTable.DataBind();