Question

For example I have 3 entities : product, tool, device. All of them have “id” and “Name” attributes. Now I try to write a method to fill entity’s data into a combobox. But I don’t now how to create a method that can pass any entity into it. Something like code below :

    private comboBox FillCombobox(List<EntityType>)
    {
        using (dowacodbEntities dowacodbEntities = new dowacodbEntities())
        {
            comboBox comboBox = new comboBox();
            List<EntityType> EntityList = dowacodbEntities.EntityType.ToList();
            DataTable dt = new DataTable();
            dt.Columns.Add("id");
            dt.Columns.Add("Name");
            dt.Rows.Add(-1, "Choose one option");
            foreach (EntityType Entity in EntityList)
            {
                dt.Rows.Add(Entity.id, Entity.Name);
            }
            comboBox.ValueMember = dt.Columns[0].ColumnName;
            comboBox.DisplayMember = dt.Columns[1].ColumnName;
            comboBox.DataSource = dt;
            return combobox;
        }
    }

Which EntityType can be product, tool or device.

Answer 1

Define interface:

public interface IBaseEntity
{
    int Id { get; }
    string Name { get; }
}

Implement that interface in your Product, Tool and Device classes (it can be implemented by your partial part if entities are autogenerated) and define your method as:

private ... FillCombobox<T>(...) where T : class, IBaseEntity
{
    using (var context = new Context())
    {
        var entities = context.CreateObjectSet<T>().ToList();
        ...
        foreach (IBaseEntity entity in entities)
        {
            dt.Rows.Add(entity.Id, entity.Name);
        }
        ...
    }
}