Support for Relations?

[leekelleher]

@Hendy mentioned this in the Gitter chatroom.

Consider adding support for Relations.

[RelationType("relationTypeAlias")]
public object RelatedItems { get; set; }

Then Ditto could get the related node IDs for the associated IPublishedContent node and pass the value to the POCO property.

e.g. @Model.RelatedItems could return a IEnumerable<IRelation> object type?

Details of the IRelation interface can be found here.

Then for more complex types a custom TypeConverter can be used:

[RelationType("relationTypeAlias")]
[TypeConverter(typeof(RelationsTypeConverter))]
public IEnumerable<IPublishedContent> RelatedItems { get; set; }

Then the custom RelationsTypeConverter can work out how to convert an IEnumerable<IRelation> into IEnumerable<IPublishedContent>.

[leekelleher]

One concern might be that the IRelationService call hits the database? Do we know if Umbraco core caches the result in memory?

[mattbrailsford]

I'd say make sure to use the Lazy< T> class so that they are only loaded when someone tries to access them. Don't want to slow down general Ditto for an edge case.

[leekelleher]

👍 on Lazy<T>.

At this stage, I'm only noting this as an idea. If we think it is too much of an edge case, then we can shelve it.

[JimBobSquarePants]

I've just pushed a new branch for you to look at. feature/allow-relations

This contains a change to the PublishedContentContext class.

The context PropertyDescriptor property now points to the property on the target class that is currently being converted. This allows us to parse any attributes on that property from within a custom TypeConverter Using the PropertyDescriptor.Attributes property.

I think that would be enough to allow what is needed. Am I correct?

[leekelleher]

You're correct!

Actually thinking about it, this might remove the need for having my UmbracoDictionaryValue attribute, as it could be handled the same way - within a specialised/custom TypeConverter.

[Hendy]

@JimBobSquarePants perfect :)

@leekelleher how about a caching factory, that'll supply 'clean' POCOs (ones that don't inherit from PublishedContetModel) so once slow relations are inflated, they are in the object graph cache

[leekelleher]

@Hendy - we already have pre/post event hooks during the conversion - see EventHandlers.cs source. You could roll your own? (Unless I'm missing a bigger benefit?)

[JimBobSquarePants]

Awesomesauce!
@leekelleher Shifting that into it's own TypeConverter would clean up the GetTypedProperty method a little anyway. It seems a good fit also and we only get strings from that don't we?

[leekelleher]

Cool. I'll look to remove the UmbracoDictionaryValue attribute (and associated code). I'll branch it off so that I can rework it later.

[JimBobSquarePants]

Ok coke... Should be simple enough too do. We still on for a release tomorrow?

[leekelleher]

Yeah, should be good for tomorrow!