Rails with Grape API - relation id in params as a filter

Question

In my Rails/Grape API app I've got an endpoint where I listed all user Notes. Model Note has optional relation with Activity model (notes can be a part of activity, like below).

class Note < ApplicationRecord
  belongs_to :user
  belongs_to :activity, optional: true
end

My endpoint looks like this:

module Notes
  class Index < Base
    desc 'All user notes',
         success: { code: 200 },
         failure: [
           { code: 401, message: 'The access token is invalid' },
           { code: 401, message: 'The access token expired' },
           { code: 404, message: "Couldn't find Notes" },
         ]

    get do
      ::DetailedSerializer.new(
        Note.where(user_id: current_user.id),
      )
    end
  end
end

I want to filter notes by activities (e.g. show notes only for activities_id = 1). To do so I need to use activities_id in params as filter but I don't know what is the syntax of such action, how to achieve that?

Answer 1

Syntax for getting params in your grape API :-

desc 'Your description.'
params do
   requires :id, type: Integer, desc: 'Model ID.'
end
get do
   Model.find(params[:id])
end

So according to your code :-

class Index < Base
    desc 'All user notes',
         success: { code: 200 },
         failure: [
           { code: 401, message: 'The access token is invalid' },
           { code: 401, message: 'The access token expired' },
           { code: 404, message: "Couldn't find Notes" },
         ]
    params do
      optional :activity_id, type: Integer, desc: 'Activity filter.'
    end
    get do
     ## then you can use this id for filter in your query
      puts "activity_id ====> #{params[:activity_id]} " 

      ::DetailedSerializer.new(
        Note.where(user_id: current_user.id),
      )
    end
  end

You can make this param optional or requires :-

params do
   optional :activity_id, type: Integer, desc: 'Activity filter.'
end

OR

params do
   requires :activity_id, type: Integer, desc: 'Activity filter.'
end