Entity Framework 4: How to find the primary key?

Question

I am trying to create a generic method using EF4 to find the primary key of an object.

example

public string GetPrimaryKey()
{
    ...
}
         


        

Answer 1

So I was finally able to find out how to get this to work. I wish I hadn't lost the link to the blog I read last night as I didn't write the code.

public T GetByPrimaryKey(int id) where T : class
{
    return (T)_db.GetObjectByKey(new EntityKey(_db.DefaultContainerName + "." + this.GetEntityName(), GetPrimaryKeyInfo().Name, id));
}

string GetEntityName()
{
    string name = typeof(T).Name;
    if (name.ToLower() == "person")
        return "People";
    else if (name.Substring(name.Length - 1, 1).ToLower() == "y")
        return name.Remove(name.Length - 1, 1) + "ies";
    else if (name.Substring(name.Length - 1, 1).ToLower() == "s")
        return name + "es";
    else
        return name + "s";
}

private PropertyInfo GetPrimaryKeyInfo()
{
    PropertyInfo[] properties = typeof(T).GetProperties();
    foreach (PropertyInfo pI in properties)
    {
        System.Object[] attributes = pI.GetCustomAttributes(true);
        foreach (object attribute in attributes)
        {
            if (attribute is EdmScalarPropertyAttribute)
            {
                if ((attribute as EdmScalarPropertyAttribute).EntityKeyProperty == true)
                    return pI;
            }
            else if (attribute is ColumnAttribute)
            {

                if ((attribute as ColumnAttribute).IsPrimaryKey == true)
                    return pI;
            }
        }
    }
    return null;
}

I hope this helps someone else. All I can say is that it should be a little clearer on how to do this.