Hi,

I think i have the skeleton of No3 now.

some helper methods to get/set the guids.

   private Guid? GetGuidValue(IRelationType item, string propertyName)
    {
        var propertyInfo = item.GetType().GetProperty(propertyName);
        if (propertyInfo == null) return null;

        var value = propertyInfo.GetValue(item);
        if (value == null) return null;

        if (value is Guid guid)
        {
            return guid;
        }

        return null;
    }

    private void SetGuidValue(object item, string propertyName, Guid? value)
    {
        var propertyInfo = item.GetType().GetProperty(propertyName);
        if (propertyInfo == null) return;

        if (propertyInfo.PropertyType == typeof(Guid?))
        {
            propertyInfo.SetValue(item, value);
        }
        else if (propertyInfo.PropertyType == typeof(Guid) && value != null)
        {
            propertyInfo.SetValue(item, Guid.Empty);
        }
    }

and a reflection method to find the new constructor should it exist (still testing all of this)

 private RelationType CreateRelation(string name, string alias, bool isBidrectional, Guid? parent, Guid? child)
    {
        // public RelationType(string name, string alias, bool isBidrectional, Guid? parentObjectType, Guid? childObjectType)

        var t = typeof(RelationType);
        var types = new Type[5];
        types[0] = typeof(string);
        types[1] = typeof(string);
        types[2] = typeof(bool);
        types[3] = typeof(Guid?);
        types[4] = typeof(Guid?);

        var constructorInfoObj = t.GetConstructor(types);
        if (constructorInfoObj != null)
        {
            var parameters = new object[5];
            parameters[0] = name;
            parameters[1] = alias;
            parameters[2] = isBidrectional;
            parameters[3] = parent;
            parameters[4] = child;

            var obj = constructorInfoObj.Invoke(parameters);
            return (RelationType)obj;
        }
        else
        {
            return new RelationType(child.Value, parent.Value, alias);
        }

    }

but equally i am just pasting from docs here, so if there is a better/nicer/more robust way....

Hi,

I see your almost there :-).

Without actually trying this out, I would say the below code in GetGuidValue() adds nothing (but also doesn't break anything).

if (value == null) return null;

In SetGuidValue() however, I believe it doesn't actually assign any value when it's a Guid and not Guid? ...

propertyInfo.SetValue(item, Guid.Empty);

I think you mean to assign value.Value, no?

propertyInfo.SetValue(item, value.Value);

The constructor-approach looks solid.

thanks for the sanity check - it does need some tidy up and yeah i got the nulls and empties mixed up.

I "think" i am going to go with if there is no value then don't do the set (i was thinking Guid.Empty on legacy sites, but that might actually cause other problems,.