API JSON authentication with Devise

registrations_controller.rb

class Api::RegistrationsController < Api::BaseController
  
  respond_to :json
  def create

    user = User.new(params[:user])
    if user.save
      render :json=> user.as_json(:auth_token=>user.authentication_token, :email=>user.email), :status=>201
      return
    else
      warden.custom_failure!
      render :json=> user.errors, :status=>422
    end
  end
end

sessions_controller.rb

class Api::SessionsController < Api::BaseController
  before_filter :authenticate_user!, :except => [:create, :destroy]
  before_filter :ensure_params_exist
  respond_to :json

  def create
    resource = User.find_for_database_authentication(:email => params[:user_login][:email])
    return invalid_login_attempt unless resource

    if resource.valid_password?(params[:user_login][:password])
      sign_in(:user, resource)
      resource.ensure_authentication_token!
      render :json=> {:success=>true, :auth_token=>resource.authentication_token, :email=>resource.email}
      return
    end
    invalid_login_attempt
  end

  def destroy
    resource = User.find_for_database_authentication(:email => params[:user_login][:email])
    resource.authentication_token = nil
    resource.save
    render :json=> {:success=>true}
  end

  protected
  def ensure_params_exist
    return unless params[:user_login].blank?
    render :json=>{:success=>false, :message=>"missing user_login parameter"}, :status=>422
  end

  def invalid_login_attempt
    render :json=> {:success=>false, :message=>"Error with your login or password"}, :status=>401
  end
end

Here is a working version for devise_jwt gem

    class SessionsController < Api::BaseController
      skip_authorization_check # cancancan
      before_action :authenticate_user!, except: [:create, :destroy]

      respond_to :json

      def create
        resource = User.find_for_database_authentication(email: login_params[:email])
        return invalid_login_attempt unless resource

        if resource.valid_password?(login_params[:password])
          sign_in(:user, resource)
          render json: { success: true }
          return
        end
        invalid_login_attempt
      end

      def destroy
        resource = User.find_for_database_authentication(email: login_params[:email])
        sign_out(resource)
        render json: { success: true }
      end

      private def login_params
        @login_params ||= params.permit(:email, :password)
      end

      protected def ensure_params_exist
        return unless params[:user_login].blank?
        render json: { success: false, message: "missing user_login parameter" }, status: 422
      end

      protected def invalid_login_attempt
        render json: { success: false, message: "Error with your login or password" }, status: 401
      end
    end

This Returns on create a response header with a valid jwt token and revokes this token on logout.

Thank you.