asked on

Trying to generate GridView columns programmatically

I have a program where I am trying to generate the columns dynamically from an IEnumerable datasource, which Ive never used before, and Im having trouble with. I assign the Datasource to the gridview and then I try to create the columns but it was orignally done in C# but I am dtrying to do it in VB.NEt so I havent been able to get this done.

Here is the code in C#...I tried to convert to VB.NET using Telerix but Im passing in a DataView as the source where in this code its passing in a dynamic source, which cant be done in VB so when I try to run the GetProperties I am getting the same values? Can someone help me out here to get this done in VB.NET passing in a DataView or a DataTable?

public static void PrepareColumns(dynamic source, DataControlFieldCollection columns, Func<string, string> headerNameFormatter)
{
// if ViewState is enabled, the columns info will be persisted between requests and we only want to add the column
// the first time the grid is requested.
if (columns.Count == 0)
{
// at this point, the datasource must have been prepared and it must be a list
var properties = source[0].GetType().GetProperties();
foreach (var property in properties)
{
var name = property.Name;

var field = new BoundField
{
DataField = name,
HeaderText =
headerNameFormatter == null
? SeperateNamesWithSpace(name)
: headerNameFormatter(name),
SortExpression = name,
HtmlEncode = false
};

if (property.PropertyType.Name == "DateTime")
{
field.DataFormatString = "{0:dd-MMM-yyyy}";
}

columns.Add(field);
}
}
}

jknj72

ASKER

Sorry I meant to say that I am NOT getting the same values in the GetProperties

it_saige

In all honesty, I believe this might be what you are after:

Module Extensions
	<System.Runtime.CompilerServices.Extension()> _
	Public Sub PrepareColumns(Of T)(ByVal source As IEnumerable(Of T), ByVal columns As DataControlFieldCollection, ByVal headerNameFormatter As Func(Of String, String))
		' if ViewState is enabled, the columns info will be persisted between requests and we only want to add the column 
		' the first time the grid is requested. 
		If columns.Count = 0 Then
			' at this point, the datasource must have been prepared and it must be a list
			Dim properties = source(0).[GetType]().GetProperties()
			For Each [property] As PropertyInfo In properties
				Dim name = [property].Name

				Dim field = New BoundField() With { _
					.DataField = name, _
					.HeaderText = If(headerNameFormatter Is Nothing, SeperateNamesWithSpace(name), headerNameFormatter(name)), _
					.SortExpression = name, _
					.HtmlEncode = False _
				}

				If [property].PropertyType.Name = "DateTime" Then
					field.DataFormatString = "{0:dd-MMM-yyyy}"
				End If

				columns.Add(field)
			Next
		End If
	End Sub
End Module

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-saige-

jknj72

ASKER

I got an error on this
"Unable to cast object of type 'System.Data.DataRowView' to type 'System.Collections.IEnumerable'. "
on
Dim properties = source(0).[GetType]().GetProperties()

In the example I am going off of it is using a System.Linq.Enumerable.WhereSelectIsIterator as the source and I am using a database so I am passing in a different type as the original. But I think Im in the ballpark!

In my example I am passing in a DataView, as the source,, which is causing a problem for me. I have the datasource set and can pass in a datatable or whatever if I need to?

Thanks for your help

jknj72

ASKER

Just so you know I prepare the DataSource prior to the Columns so maybe I need to change anything here? Again, his is obviously in C# but Im doing it in VB

public static void PrepareDataSource(
GridView gvGeneric,
StateBag viewState,
ref IEnumerable DataSource,
ref int _totalRowCount,
Func<GridViewSortEventArgs, IEnumerable> sorting)
{
var column = viewState[Const.SortExpression] as string;
SortDirection sortDirection = SortDirection.Ascending;
if (viewState[Const.SortDirection] != null)
{
sortDirection = (SortDirection)viewState[Const.SortDirection];
}

var temp = DataSource.Cast<object>();
_totalRowCount = temp.Count();

if (column != null)
{
var source = SortingHelper.GetSortedObjects(new GridViewSortEventArgs(column, sortDirection), temp, sorting);
DataSource = source;
}
else if (DataSource.GetType().Name != Const.ListTypeName)
{
DataSource = temp.ToList();
}

gvGeneric.DataSource = DataSource;
}

it_saige

I'm not seeing where you prepare the columns. Can provide the code associated with this? Also it would help if you use code blocks.

1. Press the '[b]CODE[/b]' glyph in the formatting bar.

2. This will insert code blocks.

3. Code is formatted like the following.

This is example code

Open in new window

-saige-

jknj72

ASKER

Ok sorry, I just pasted it in there? Could you not see my first post with the code in it? The Sub was called PrepareColumns

 public static void PrepareColumns(dynamic source, DataControlFieldCollection columns, Func<string, string> headerNameFormatter)
        {
            // if ViewState is enabled, the columns info will be persisted between requests and we only want to add the column 
            // the first time the grid is requested. 
            if (columns.Count == 0)
            {
                // at this point, the datasource must have been prepared and it must be a list
                var properties = source[0].GetType().GetProperties();
                foreach (var property in properties)
                {
                    var name = property.Name;

                    var field = new BoundField
                                    {
                                        DataField = name,
                                        HeaderText =
                                            headerNameFormatter == null
                                                ? SeperateNamesWithSpace(name)
                                                : headerNameFormatter(name),
                                        SortExpression = name,
                                        HtmlEncode = false
                                    };

                    if (property.PropertyType.Name == "DateTime")
                    {
                        field.DataFormatString = "{0:dd-MMM-yyyy}";
                    }

                    columns.Add(field);
                }
            }
        }

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and then the PrepareDataSource which I call before the PrepareColumns

      public static void PrepareDataSource(
            GridView gvGeneric,
            StateBag viewState,
            ref IEnumerable DataSource,
            ref int _totalRowCount,
            Func<GridViewSortEventArgs, IEnumerable> sorting)
        {
            var column = viewState[Const.SortExpression] as string;
            SortDirection sortDirection = SortDirection.Ascending;
            if (viewState[Const.SortDirection] != null)
            {
                sortDirection = (SortDirection)viewState[Const.SortDirection];
            }

            var temp = DataSource.Cast<object>();
            _totalRowCount = temp.Count();

            if (column != null)
            {
                var source = SortingHelper.GetSortedObjects(new GridViewSortEventArgs(column, sortDirection), temp, sorting);
                DataSource = source;
            }
            else if (DataSource.GetType().Name != Const.ListTypeName)
            {
                DataSource = temp.ToList();
            }

            gvGeneric.DataSource = DataSource;
        }

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Hope I did it correctly and thanks for your help!!!

jknj72

ASKER

oh I see what you mean now...Thanks for the correction

it_saige

You did fine.

To clarify, where is the code that calls the PrepareColumns and PrepareDataSource methods?

-saige-

jknj72

ASKER

Ahh sorry...Here it is... In my code I had to take out the sorting in the DataSource call and the HeaderFormatter in the Column call, so you could ignore those parameters because I couldnt figure out the C# conversion to VB.NET so I had to work around it

        
    Public DataSource As IEnumerable
    'Public Event HeaderFormatting As Func(Of String, String)
    'Public Event Sorting As Func(Of GridViewSortEventArgs, IEnumerable)

        gvGeneric.AllowPaging = AllowSorting
        gvGeneric.AllowSorting = AllowSorting

        DataSourceHelper.PrepareDataSource(gvGeneric, ViewState, DataSource, _totalRowCount) ', Sorting(e))
        ColumnHelper.PrepareColumns(DataSource, gvGeneric.Columns) ', HeaderFormatting)

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jknj72

ASKER

Im thinking I need to convert the DataSource to a list because thats what they had it as in the example. I just created a dataset and tried to pass it in that way(tried a dataview as well) and it didnt work.

ASKER CERTIFIED SOLUTION

it_saige

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jknj72

ASKER

thanks Saige