Entity Framework will only set related entity property to “null” if I first get the property

Question

Edit This seems to occur for any Entity property that references another entity in one direction. In other words, for the below example, the fact

Answer 1

I am not happy with the official workaround:

    context.Entry(foo).Reference(f => f.Bar).CurrentValue = null;

because it involves too much contextual knowledge by the user of the POCO object. My fix is to trigger a load of the lazy property when setting the value to null so that we do not get a false positive comparison from EF:

    public virtual User CheckoutUser
    {
        get { return checkoutUser; }
        set
        {
            if (value != null || !LazyPropertyIsNull(CheckoutUser))
            {
                checkoutUser = value;
            }
        }
    }

and in my base DbEntity class:

    protected bool LazyPropertyIsNull(T currentValue) where T : DbEntity
    {
        return (currentValue == null);
    }

Passing the property to the LazyPropertyIsNull function triggers the lazy load and the correct comparison occurs.

Please vote for this issue on the EF issues log: