With respect to the developers working on ExAdmin (and ActiveAdmin, which was the inspiration) these tools run completely contrary to building maintainable software. They encourage the tightest coupling not only between parts of your own software, but to the libraries they are built on. If you are building a small CRUD application that you need a quick-and-dirty admin interface for, by all means, they’re useful for prototyping such a thing. But if you are building an application that drives your business and you let your architecture and techniques be dictated by the constraints of a protoyping tool… man, you are in for a world of hurt. Its been awhile since I looked at ExAdmin, so maybe its come along since the last time I looked at it, but the last time I did it had the same shortcomings as ActiveAdmin in an utter and complete dependence on Ecto’s associations.
I personally don’t really like using examples like a Blog for illustrating an idea like contexts because its such a simple modelling domain that any distinction between contexts is very contrived, which leads to questions like this one. (I’m not knocking you for asking it, btw, its a perfectly legitimate thing to want to do in that context.) Lets say then that blogs are a smaller feature within a larger application and you want to separate an authentication context from a content context. One thing I would do here is create a separate schema backed by the same table with only the relevant information (e.g. name, email) in it. Then you can create associations between this new version of a user (we’ll call it Author, backed by the users table) and the Post schema. However, unlike the Account version of a user (from the Auth) context, you wouldn’t have changesets available to create a new author or even update the author record.
This isn’t the only way to preserve boundaries between contexts—I honestly feel like its cheating a little because you’ve got them coupled at the database level, though this does preserve some independence between them. In a richer domain it would make sense to reach for other tools. But also, if your application is really just a blog, then you’re in something that is A) quite simple, behaviorally, and B) straight up CRUD. I probably wouldn’t go reaching for a lot of separate contexts for this use-case.
