Rows cannot be programmatically added to the DataGridView's rows collection when the control is data-bound error on collection data source

Question

I know there are threads on this error but i only found solutions in case the data source is a table. In my case the data source is a list. Here is my code:

    private void AdminForm_Load(object sender, EventArgs e)
    {
        dgUser.DataSource = read.getUsers();
        dgUser.Rows.Add();
    }

So apparently the Add() method doesn't work for collections. Any solutions?

Answer 1

List<String> list = new List<String>();
list.add("val1");
dataGridView1.DataSource = list;
list.add("val2");
dataGridView1.DataSource = null;
dataGridView1.DataSource = list;

In this case you have to set datasource to null, and then again to list; Or better to use Binding list

BindingList <String> list = new BindingList<String>();
list.Add("val1");
dataGridView1.DataSource = list;
list.Add("val1");

In this case you dont have to "refresh" anything, its done automatically

Answer 2

Try code below. Additional you can check collection type in line 4.

private bool AddNewRow(DataGridView grid)
{
    var collection = grid.DataSource;
    if (collection == null)
    {
        grid.Rows.Add();
        return true;
    }

    var itemType = GetCollectionItemType(collection.GetType());
    if (itemType != null && itemType != typeof(object) && !itemType.IsAbstract && itemType.GetConstructor(Type.EmptyTypes) != null)
    {
        try
        {
            dynamic item = Activator.CreateInstance(itemType);
            ((dynamic)collection).Add(item);

            if (!(collection is System.ComponentModel.IBindingList))
            {
                grid.DataSource = null;
                grid.DataSource = collection;
            }

            return true;
        }
        catch { }
    }

    return false;
}
public static Type[] GetGenericArguments(this Type type, Type genericTypeDefinition)
{
    if (!genericTypeDefinition.IsGenericTypeDefinition)
        return Type.EmptyTypes;

    if (genericTypeDefinition.IsInterface)
    {
        foreach (var item in type.GetInterfaces())
            if (item.IsGenericType && item.GetGenericTypeDefinition().Equals(genericTypeDefinition))
                return item.GetGenericArguments();
    }
    else
    {
        for (Type it = type; it != null; it = it.BaseType)
            if (it.IsGenericType && it.GetGenericTypeDefinition().Equals(genericTypeDefinition))
                return it.GetGenericArguments();
    }

    return new Type[0];
}
public static Type GetCollectionItemType(Type collectionType)
{
    var args = GetGenericArguments(collectionType, typeof(IEnumerable<>));
    if (args.Length == 1)
        return args[0];

    return typeof(IEnumerable).IsAssignableFrom(collectionType)
        ? typeof(object)
        : null;
}

Answer 3

   var dataSource = datagrid.DataSource;
                    (dataSource as IList).Add(obj);
                    datagrid.DataSource = null;
                    datagrid.DataSource = dataSource;
                    datagrid.Refresh();