UserMapping Scope

[randellhodges]

This is probably an edge case with limit use.

I have a few mappings I'm converting from Automapper that makes use of the AddTransform feature. For example:

.AddTransform<ICollection<string>>(collection => collection.DistinctAndSort());

So, after mapping, it basically ensures that the collection is sorted and distinct. I understand it would be better to ensure that happens before it makes it this far, but that is another conversation :)

I know that I could do a [UserMapping(Default = true)] but I don't want to do that for every ICollection in the mapping.

I could do a [MapProperty(..., ..., Use = nameof(SomeMethod))] , but then I'd be doing that dozens of times and if I add another ICollection to that object, I'd have to remember to map that.

I was thinking, would there be other uses for something like [UserMapping(Scope = "SomeName")] and then you could apply an attribute like [MapScope("SomeName")] so that only those that match the scope would get applied to that instance of the mapping.

A few things that would make this not worth implementing:

1. Any one else have a use beyond me?
2. Probably need to be able to have support for multiple scopes
3. Order resolving the scopes

Just an idea to avoid having to put a dozen attributes on my partial mapper definition.

[latonz]

We won’t add support for this directly in Mapperly since it’s more business logic than mapping logic. Mapperly’s goal is to focus on generating type-safe mappings, and transformations like enforcing DistinctAndSort() are better expressed explicitly in your own code.

If you really want to do it in the Mapperly, #451 could simplify it (would allow to implement a generic collection to collection user implemented mapping).

At the same time, this does look like a fairly edge case with limited usage outside of scenarios like yours. That’s why we’d prefer to keep the core of Mapperly simple.