EntityFramework Code First – Check if Entity is attached

You can find the answer here.

public bool Exists<T>(T entity) where T : class
{
    return this.Set<T>().Local.Any(e => e == entity);
}

Place that code into your context or you can turn it into an extension like so.

public static bool Exists<TContext, TEntity>(this TContext context, TEntity entity)
    where TContext : DbContext
    where TEntity : class
{
    return context.Set<TEntity>().Local.Any(e => e == entity);
}