R – ASP.NET GridView – Editing Dynamic Template Columns

asp.netgridviewitemplate

I have created a GridView whose columns are dynamically created based on my data source. I have implemented these columns by using the approach described here.Those columns display properly on the initial load. However, I need to implement commanding so that a user can edit / delete a row in the GridView.

At this point, I have implemented commanding as I would with a normal GridView. I have a TemplateField with an ItemTemplate that has LinkButton elements for edit and delete. The CommandName for each LinkButton is set to either Edit or Delete respectively.

Oddly, when a user clicks either the Edit or Delete link, the data in the GridView disappears. However, I have verified that I am in fact re-binding the data when one of these LinkButton elements is selected.

Can anyone provide some suggestions as to what the cause could be?

Thank you!

Best Answer

Here are good examples. You can figure out postback issue.

http://quickstarts.asp.net/QuickStartV20/aspnet/

Related Solutions

Adding dynamic columns to an ASP.NET Gridview

I recently conquered silmilar issues with dynamic columns in gridviews, perhaps this will help.

First turn the viewstate off
Second add the columns programatically in a function fired in the oninit event
Lastly I used the following helper class to cause the checkboxes to instantiate when the RowDataBound event kicked off. Yes some of it is hard coded.

Heck here is all the code. Have at it :) Warrenty as is, blah blah blah...

Finally since I am just getting my feet wet DotNet any tips would be appreciated [IE don't rip me too much :) ]. And yes 'borrowed' the initial code from the web somewhere, sorry I cant remember off the top of my head :(

-- Fire this off in protected override void OnInit

    private void GridViewProject_AddColumns()
    {
        DataSet dsDataSet = new DataSet();
        TemplateField templateField = null;

        try
        {
            StoredProcedure sp = new StoredProcedure("ExpenseReportItemType_GetList", "INTRANETWEBDB", Context.User.Identity.Name);
            dsDataSet = sp.GetDataSet();

            if (sp.RC != 0 && sp.RC != 3000)
            {
                labelMessage.Text = sp.ErrorMessage;
            }

            int iIndex = 0;
            int iCount = dsDataSet.Tables[0].Rows.Count;
            string strCategoryID = "";
            string strCategoryName = "";
            iStaticColumnCount = GridViewProject.Columns.Count;

            // Insert all columns immediatly to the left of the LAST column
            while (iIndex < iCount)
            {
                strCategoryName = dsDataSet.Tables[0].Rows[iIndex]["CategoryName"].ToString();
                strCategoryID = dsDataSet.Tables[0].Rows[iIndex]["CategoryID"].ToString();

                templateField = new TemplateField();
                templateField.HeaderTemplate = new GridViewTemplateExternal(DataControlRowType.Header, strCategoryName, strCategoryID);
                templateField.ItemTemplate = new GridViewTemplateExternal(DataControlRowType.DataRow, strCategoryName, strCategoryID);
                templateField.FooterTemplate = new GridViewTemplateExternal(DataControlRowType.Footer, strCategoryName, strCategoryID);

                // Have to decriment iStaticColumnCount to insert dynamic columns BEFORE the edit row
                GridViewProject.Columns.Insert((iIndex + (iStaticColumnCount-1)), templateField);
                iIndex++;
            }
            iFinalColumnCount = GridViewProject.Columns.Count;
            iERPEditColumnIndex = (iFinalColumnCount - 1); // iIndex is zero based, Count is not
        }
        catch (Exception exception)
        {
            labelMessage.Text = exception.Message;
        }
    }

-- Helper Class

public class GridViewTemplateExternal : System.Web.UI.ITemplate
{
    #region Fields
    public DataControlRowType DataRowType;
    private string strCategoryID;
    private string strColumnName;
    #endregion

    #region Constructor
    public GridViewTemplateExternal(DataControlRowType type, string ColumnName, string CategoryID)
    {
        DataRowType = type; // Header, DataRow,
        strColumnName = ColumnName; // Header name
        strCategoryID = CategoryID;
    }
    #endregion

    #region Methods
    public void InstantiateIn(System.Web.UI.Control container)
    {
        switch (DataRowType)
        {
            case DataControlRowType.Header:
                // build the header for this column
                Label labelHeader = new Label();
                labelHeader.Text = "<b>" + strColumnName + "</b>";
                // All CheckBoxes "Look Up" to the header row for this information
                labelHeader.Attributes["ERICategoryID"] = strCategoryID;
                labelHeader.Style["writing-mode"] = "tb-rl";
                labelHeader.Style["filter"] = "flipv fliph";
                container.Controls.Add(labelHeader);
                break;
            case DataControlRowType.DataRow:
                CheckBox checkboxAllowedRow = new CheckBox();
                checkboxAllowedRow.Enabled = false;
                checkboxAllowedRow.DataBinding += new EventHandler(this.CheckBox_DataBinding);
                container.Controls.Add(checkboxAllowedRow);
                break;
            case DataControlRowType.Footer:
                // No data handling for the footer addition row
                CheckBox checkboxAllowedFooter = new CheckBox();
                container.Controls.Add(checkboxAllowedFooter);
                break;
            default:
                break;
        }
    }
    public void CheckBox_DataBinding(Object sender, EventArgs e)
    {
        CheckBox checkboxAllowed = (CheckBox)sender;// get the control that raised this event
        GridViewRow row = (GridViewRow)checkboxAllowed.NamingContainer;// get the containing row
        string RawValue = DataBinder.Eval(row.DataItem, strColumnName).ToString();
        if (RawValue.ToUpper() == "TRUE")
        {
            checkboxAllowed.Checked = true;
        }
        else
        {
            checkboxAllowed.Checked = false;
        }
    }
    #endregion
}

.net – ASP.NET Web Site or ASP.NET Web Application

Website:

The Web Site project is compiled on the fly. You end up with a lot more DLL files, which can be a pain. It also gives problems when you have pages or controls in one directory that need to reference pages and controls in another directory since the other directory may not be compiled into the code yet. Another problem can be in publishing.

If Visual Studio isn't told to re-use the same names constantly, it will come up with new names for the DLL files generated by pages all the time. That can lead to having several close copies of DLL files containing the same class name, which will generate plenty of errors. The Web Site project was introduced with Visual Studio 2005, but it has turned out not to be popular.

Web Application:

The Web Application Project was created as an add-in and now exists as part of SP 1 for Visual Studio 2005. The main differences are the Web Application Project was designed to work similarly to the Web projects that shipped with Visual Studio 2003. It will compile the application into a single DLL file at build time. To update the project, it must be recompiled and the DLL file published for changes to occur.

Another nice feature of the Web Application project is it's much easier to exclude files from the project view. In the Web Site project, each file that you exclude is renamed with an excluded keyword in the filename. In the Web Application Project, the project just keeps track of which files to include/exclude from the project view without renaming them, making things much tidier.

Reference

The article ASP.NET 2.0 - Web Site vs Web Application project also gives reasons on why to use one and not the other. Here is an excerpt of it:

You need to migrate large Visual Studio .NET 2003 applications to VS 2005? use the Web Application project.

You want to open and edit any directory as a Web project without creating a project file? use Web Site project.

You need to add pre-build and post-build steps during compilation? use Web Application project.

You need to build a Web application using multiple Web projects? use the Web Application project.

You want to generate one assembly for each page? use the Web Site project.

You prefer dynamic compilation and working on pages without building entire site on each page view? use Web Site project.

You prefer single-page code model to code-behind model? use Web Site project.

Web Application Projects versus Web Site Projects (MSDN) explains the differences between the web site and web application projects. Also, it discusses the configuration to be made in Visual Studio.