Binding an enum in a datatable

[Anthony Daniel]

I have bound a BindingList holding my business objects to a GridView which displays fine.  Then I reset the grid and I converted the list to a DataTable and bind it to a gridview.  The business objects have an enum property for which the appropriate string name is displayed when the objects are bound, however only the integer value of the enum is displayed when the datatable is bound.  I use the same predefined group of GridViewDataColumns for both scenarios.  The extension method generates a datacolumn with the datatype of my enum.  What should I do to get the enum string name to display when the datatable is bound?  I just want the string in a textbox, this grid is strictly read only.

List<WorkItem> _workitems = new List<WorkItem>();
List<GridViewDataColumn> _workitemColumns = new List<GridViewDataColumn>();

_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "InstanceID", HeaderText = "Instance ID" });
_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "StorageObjectID", HeaderText = "Object ID" });
_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "Document.BatchID", HeaderText = "Batch ID" });
_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "ReferenceTypeName", HeaderText = "Document Type" });
_workitemColumns.Add(new GridViewDateTimeColumn() { DataField = "CreateDate", HeaderText = "Create Date", ExcelExportType = DisplayFormatType.Custom, ExcelExportFormatString = "MM/dd/yyyy hh:mm:ss" });
_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "Title", HeaderText = "Title" });
_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "OwningUser", HeaderText = "Assigned User" });
_workitemColumns.Add(new GridViewTextBoxColumn() { DataField = "Status", HeaderText = "Status"});

#region this works

foreach (GridViewDataColumn curCol in this._workitemColumns)
{
    this.workItemsGridView1.Columns.Add(curCol);
}

BindingList<WorkItem> bindingWorkitems = new BindingList<WorkItem>(this._workitems);
BindingSource dbBindSource = new BindingSource();
dbBindSource.DataSource = bindingWorkitems;
this.workItemsGridView1.DataSource = dbBindSource;

#endregion

#region does not work

DataTable workitemsDT = this._workitems.ToDataTable();

foreach (GridViewDataColumn curCol in this._workitemColumns)
{
    this.workItemsGridView1.Columns.Add(curCol);
}

foreach(GridViewDataColumn curCol in this._layerColumns[this._selectedLayer])
{
    this.workItemsGridView1.Columns.Add(curCol);
}

this.workItemsGridView1.DataSource = workitemsDT;

#endregion

public static DataTable ToDataTable<T>(this List<T> items)
{
    var tb = new DataTable(typeof(T).Name);

    PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

    foreach (var prop in props)
    {
    if (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
    {
        tb.Columns.Add(prop.Name, prop.PropertyType.GetGenericArguments()[0]);
    }
    else
        tb.Columns.Add(prop.Name, prop.PropertyType);
    }

    foreach (var item in items)
    {
    var values = new object[props.Length];
    for (var i = 0; i < props.Length; i++)
    {
        values[i] = props[i].GetValue(item, null);
    }

    tb.Rows.Add(values);
    }

    return tb;
}

[Julian Benkov]

Hello Anthony,

You can check the PropertyInfo type for Enum and get the name of the variable in this case to save it in the DataTable. In addition, you should create a string DataColumn in this scenario:

public static DataTable ToDataTable<T>(this List<T> items)
{
    var tb = new DataTable(typeof(T).Name);

    PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

    foreach (var prop in props)
    {
        if (prop.PropertyType.IsEnum)
        {
            tb.Columns.Add(prop.Name, typeof(string));
        }
        else if (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
        {
            tb.Columns.Add(prop.Name, prop.PropertyType.GetGenericArguments()[0]);
        }
        else
            tb.Columns.Add(prop.Name, prop.PropertyType);
    }

    foreach (var item in items)
    {
        var values = new object[props.Length];
        for (var i = 0; i < props.Length; i++)
        {
            if (props[i].PropertyType.IsEnum)
            {
                object val = props[i].GetValue(item, null);
                values[i] = Enum.GetName(props[i].PropertyType, val);
            }
            else
            {
                values[i] = props[i].GetValue(item, null);
            }
        }

        tb.Rows.Add(values);
    }

    return tb;
}public static DataTable ToDataTable<T>(this List<T> items)
{
    var tb = new DataTable(typeof(T).Name);

    PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

    foreach (var prop in props)
    {
        if (prop.PropertyType.IsEnum)
        {
            tb.Columns.Add(prop.Name, typeof(string));
        }
        else if (prop.PropertyType.IsGenericType && prop.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
        {
            tb.Columns.Add(prop.Name, prop.PropertyType.GetGenericArguments()[0]);
        }
        else
            tb.Columns.Add(prop.Name, prop.PropertyType);
    }

    foreach (var item in items)
    {
        var values = new object[props.Length];
        for (var i = 0; i < props.Length; i++)
        {
            if (props[i].PropertyType.IsEnum)
            {
                object val = props[i].GetValue(item, null);
                values[i] = Enum.GetName(props[i].PropertyType, val);
            }
            else
            {
                values[i] = props[i].GetValue(item, null);
            }
        }

        tb.Rows.Add(values);
    }

    return tb;
}

I hope this helps.

All the best,
Julian Benkov
the Telerik team