An opinionated abstraction of DataFactory?

Comments

1. 

   Magnus Paulsson 1 years ago

   Not an answer to your questions, but a general comment/opinion: I don't think GetChildrenVisibleForVisitor or GetChildrenVisibleInMenus should be included in the interface. I would rather have general VisibleForVisitor and VisibleInMenus extension methods. It just feels cleaner to leave the filtering out of the interface, otherwise why not have GetChildrenAlphabetical, GetChildrenByIndex, GetDescendantsStartingWithLetterB (ok that's absurd, but I'm trying to make a point here ;) ). I might be missing something though, that requires the methods to be in there.
2. 

   Joel Abrahamsson 1 years ago

   Magnus,
   
   The problem with extension methods is that you cannot isolate your code from the code in them. That's not a problem for simple methods that do string manipulation, filtering based on properties of objects in a collection etc. But when an extension method has external dependencies any code that uses it is more or less impossible to test using unit tests.
   
   Therefore methods for filtering must be declared in something abstract, such as an interface.
   
   One could argue though that there should be a separate interface for filtering. I agree with that, but from a pragmatic standpoint, given that it's extremely common to retrieve a page's children filtered by access it might be warranted to include that in the general interface? Would love to hear more reactions to this view though!
3. 

   Magnus Paulsson 1 years ago

   Hah, you could say that I completely missed the point of it all then :)
4. 

   Stefan Forsberg 1 years ago

   Some additions to the MSN-feedback I already gave =)
   
   1. Yes, sounds reasonable
   
   5. IEnumerable, ICollection or IList. As long as it's not List or another of the concrete implementations.
   
   Another thing, I'm not sure exactly what data it should return but have you given any thoughts to return some form of Null Object from instead of null? To save the user of a lot if null checks (instead of try/catch).
   
5. 

   Joel Abrahamsson 1 years ago

   Stefan,
   
   Could you elaborate regarding #5? It would be convenient to get Lists, but on the other hand I figure that the methods will then have to do .ToList() while in 80-90% of the cases you can just do with IEnumerable.
   
   Regarding null objects etc I got some feedback regarding that on Twitter. My current idea is to let the methods continue to throw PageNotFoundException as well as a new PageNotOfExpectedTypeException but also add a couple of TryGetPage methods. What do you think?
6. 

   Stefan Forsberg 1 years ago

   I'd say go with IEnumerable then. Btw, on another sort of related subject. How will your FilterForVisitor methods work? Will they convert the IEnumerables to PageDataCollections and use EPi's filters and then back to IEnumerable or are you doing the filtering yourself?
   
   Aha, a TryGet approach would work really well I think.
7. 

   Joel Abrahamsson 1 years ago

   I'm thinking that they will look something like this:
   

   PageDataCollection children = DataFactory.Instance.GetPage();
   PageDataCollection filteredChildren = FilterForVisitor.Filter(children);
   return filteredChildren.OfType();
   
8. 

   Blake Payne 1 months ago

   Happy New Year to All!