Using Reflection to create a DataTable from a Class?

Question

I\'ve just learned about Generics and I\'m wondering whether I can use it to dynamically build datatables from my classes.

Or I might be missing the point here. Here

Answer 1

my favorite homemade function. it create and populate all at same time. throw any object.

 public static DataTable ObjectToData(object o)
 {
    DataTable dt = new DataTable("OutputData");

    DataRow dr = dt.NewRow();
    dt.Rows.Add(dr);

    o.GetType().GetProperties().ToList().ForEach(f =>
    {
        try
        {
            f.GetValue(o, null);
            dt.Columns.Add(f.Name, f.PropertyType);
            dt.Rows[0][f.Name] = f.GetValue(o, null);
        }
        catch { }
    });
    return dt;
 }

Answer 2

Here's a VB.Net version that creates a data table from a generic list passed to the function as an object. There is also a helper function (ObjectToDataTable) that creates a data table from an object.

Imports System.Reflection

   Public Shared Function ListToDataTable(ByVal _List As Object) As DataTable

    Dim dt As New DataTable

    If _List.Count = 0 Then
        MsgBox("The list cannot be empty. This is a requirement of the ListToDataTable function.")
        Return dt
    End If

    Dim obj As Object = _List(0)
    dt = ObjectToDataTable(obj)
    Dim dr As DataRow = dt.NewRow

    For Each obj In _List

        dr = dt.NewRow

        For Each p as PropertyInfo In obj.GetType.GetProperties

            dr.Item(p.Name) = p.GetValue(obj, p.GetIndexParameters)

        Next

        dt.Rows.Add(dr)

    Next

    Return dt

End Function

Public Shared Function ObjectToDataTable(ByVal o As Object) As DataTable

    Dim dt As New DataTable
    Dim properties As List(Of PropertyInfo) = o.GetType.GetProperties.ToList()

    For Each prop As PropertyInfo In properties

        dt.Columns.Add(prop.Name, prop.PropertyType)

    Next

    dt.TableName = o.GetType.Name

    Return dt

End Function

Answer 3

Here is a little bit modified code, which fixed time zone issue for datatime fields:

    public static DataTable ToDataTable<T>(this IList<T> data)
    {
        PropertyDescriptorCollection props =
            TypeDescriptor.GetProperties(typeof(T));
        DataTable table = new DataTable();
        for (int i = 0; i < props.Count; i++)
        {
            PropertyDescriptor prop = props[i];
            table.Columns.Add(prop.Name, prop.PropertyType);
        }
        object[] values = new object[props.Count];
        foreach (T item in data)
        {
            for (int i = 0; i < values.Length; i++)
            {
                if (props[i].PropertyType == typeof(DateTime))
                {
                    DateTime currDT = (DateTime)props[i].GetValue(item);
                    values[i] = currDT.ToUniversalTime();
                }
                else
                {
                    values[i] = props[i].GetValue(item);
                }
            }
            table.Rows.Add(values);
        }
        return table;
    }

Answer 4

Using the answer provided by @neoistheone I've changed the following sections. Works fine now.

DataTable dogTable = new DataTable();
        dogTable = CreateDataTable(typeof(Dog));

        dogTable.Rows.Add(Killer.Breed, Killer.Name,Killer.legs,Killer.tail);

        foreach (DataRow row in dogTable.Rows)
        {
            Console.WriteLine(row.Field<string>("Name") + " " + row.Field<string>("Breed"));
            Console.ReadLine();
        }

Answer 5

Here is a more compact version of David's answer that is also an extension function. I've posted the code in a C# project on Github.

public static class Extensions
{
    public static DataTable ToDataTable<T>(this IEnumerable<T> self)
    {
        var properties = typeof(T).GetProperties();

        var dataTable = new DataTable();
        foreach (var info in properties)
            dataTable.Columns.Add(info.Name, Nullable.GetUnderlyingType(info.PropertyType) 
               ?? info.PropertyType);

        foreach (var entity in self)
            dataTable.Rows.Add(properties.Select(p => p.GetValue(entity)).ToArray());

        return dataTable;
    }     
}

I have found that this works very well in conjunction with code to write a DataTable to CSV.

Answer 6

Building up on all the previous answers, here is a version that creates a DataTable from any collection:

public static DataTable CreateDataTable<T>(IEnumerable<T> list)
{
    Type type = typeof(T);
    var properties = type.GetProperties();      

    DataTable dataTable = new DataTable();
    foreach (PropertyInfo info in properties)
    {
        dataTable.Columns.Add(new DataColumn(info.Name, Nullable.GetUnderlyingType(info.PropertyType) ?? info.PropertyType));
    }

    foreach (T entity in list)
    {
        object[] values = new object[properties.Length];
        for (int i = 0; i < properties.Length; i++)
        {
            values[i] = properties[i].GetValue(entity);
        }

        dataTable.Rows.Add(values);
    }

    return dataTable;
}