active_model_serializers/docs/general/passing_arbitrary_options.md

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# Passing Arbitrary Options To A Serializer

Let's say you have a basic Post Controller:

```ruby
class PostController < ApplicationController
  def dashboard  
    render json: @posts
  end
end
```

Odds are, your serializer will look something like this:

```ruby
class PostSerializer < ActiveModel::Serializer
  attributes :id, :title, :body
end
```

This works all fine and well, but maybe you passing in some arbitrary options
into the serializer. These options can be anything that isn't already reserved for use by
ActiveModelSerializers' adapter options.

Here's an example:

```ruby
# posts_controller.rb
class PostController < ApplicationController
  def dashboard  
    render json: @posts, user_id: 12
  end
end

# post_serializer.rb
class PostSerializer < ActiveModel::Serializer
  attributes :id, :title, :body

  def comments_by_me  
    Comments.where(user_id: instance_options[:user_id], post_id: object.id)
  end
end
```