Bringing Filter to 0.10.x

[joaomdmoura]

tl;dr

Older versions of AMS had a filterfeature that older users are used to. We would like to bring this to 0.10.x.

---

Older versions of AMS had a filterfeature that older users are used to.
We would like to bring this to 0.10.x mainly for two reasons:

1. There is no easy way to filter attributes on 0.10.x so far
2. It will help ppl to update from 0.8 and 0.9

The idea is to provide a method named filter, which should return an array used to determine what attributes and associations should be included in the output. This is typically used to customize output based on current_user. For example:

class PostSerializer < ActiveModel::Serializer
  attributes :id, :title, :body, :author

  def filter(keys)
    if scope.admin?
      keys
    else
      keys - [:author]
    end
  end
end

---

related to issues:

• filter method called multiple times. #459

related to PRs:

• Fixes filter method being called multiple times.  #460
• add if/unless options to attribute #1266

[bf4]

This is also a feature of the JSON API

• http://jsonapi.org/format/#fetching-filtering
• http://jsonapi.org/recommendations/#filtering

[joaomdmoura]

But in specific to JSON-API I think the fields implementation is covering it.

[bf4]

Not sure I understand. Fields is different.

• http://jsonapi.org/format/#fetching-sparse-fieldsets
• http://jsonapi.org/examples/

[joaomdmoura]

Yup, you're right I messed up.
It seems it's not necessary but it's a recommendation that we should aim for.

It seems to me that some cases are not so useful, taking into considerations the rails context we usually have, like:
GET /comments?filter[post]=1

But as I said, is part of the convention and we should aim for that. 😄
Would be awesome to have filter back working out of the box with the filtering patter on json-api.