为什么我得到这个`ActiveRecord :: RecordNotFound。 （找不到'id'）`我的Rails API中的POST请求出错？

Question

Some context. I am creating an API that is contacted by an external server. This external server contacts the API with POST requests to the endpoint /vehicles with a unique id number. The request body has the format { "id": “some_string_here” } . My API stores these in the db. After the vehicles have been created the external server then makes POST requests with the endpoint vehicles/:id/locations with the request body looking something like this { "lat": 10.0, "lng": 20.0, "at": "2019-09-01T12:00:00Z" } - adding lat lng coordinates and a time stamp to each vehicle periodically (to update the vehicle's location).

I have been able to set up my API with vehicles and locations controllers and when I start the external server the vehicles are stored successfully. The problem I have is when the server then starts to send requests to add locations to each vehicle. In the console I get the message:

Processing by LocationsController#create as HTML

  Parameters: {"lat"=>52.44381, "lng"=>13.47686, "at"=>"2019-07-28T16:56:45.311Z", "vehicle_id"=>"d759fc35-b25c-4877-8e40-9b0104447b31", "location"=>{"lat"=>52.44381, "lng"=>13.47686, "at"=>"2019-07-28T16:56:45.311Z"}}
ActiveRecord::RecordNotFound (Couldn't find Vehicle with 'id'=d6880741-ae7f-4741-aa04-950b0a1e2d3b):
Can't verify CSRF token authenticity.

app/controllers/locations_controller.rb:9:in `create'
  Vehicle Load (38.2ms)  SELECT  "vehicles".* FROM "vehicles" WHERE "vehicles"."id" = $1 LIMIT $2  [["id", 0], ["LIMIT", 1]]
  ↳ app/controllers/locations_controller.rb:9
Completed 404 Not Found in 50ms (ActiveRecord: 38.2ms)

ActiveRecord::RecordNotFound (Couldn't find Vehicle with 'id'=d759fc35-b25c-4877-8e40-9b0104447b31):

The problem might have something to do with the fact that the requests to store a vehicle have id as the key in the body (the same name as the default primary key column name). This meant that I had to create a new column for the vehicle id that the server is passing and then add this code in my controller to change the params hash:

def vehicle_params
  params[:vehicle][:unique_id] = params[:vehicle].delete(:id)
end 

This meant that vehicles were stored correctly, however it may (or may not) be the reason why I am getting the error message described above. Any ideas how I can fix this? My relevant code is below.

vehicles_controller.rb

class VehiclesController < ApplicationController
...
  def create
    @vehicle = Vehicle.new(vehicle_params)

    respond_to do |format|
      if @vehicle.save
        format.json { render status: :created, location: @vehicle }
      else
        format.json { render json: @vehicle.errors, status: :unprocessable_entity }
      end
    end
  end

  private

    def vehicle_params
      # swap id column value with unique_id to avoid conflict with primary key
      params[:vehicle][:unique_id] = params[:vehicle].delete(:id)
      params.require(:vehicle).permit(:unique_id)
    end
end

locations_controller.rb

class LocationsController < ApplicationController
...
  def create
    @vehicle = Vehicle.find(params[:vehicle_id])
    @location = @vehicle.locations.new(location_params)


    respond_to do |format|
      if @location.save
        format.json { render :show, status: :created, location: @vehicle }
      else
        format.json { render json: @location.errors, status: :unprocessable_entity }
      end
    end
  end

  private

    def location_params
      params.require(:location).permit(:lat, :lng, :at, :vehicle_id)
    end
end

routes.rb

Rails.application.routes.draw do
  resources :vehicles do
    resources :locations
  end
end

schema.rb

ActiveRecord::Schema.define(version: 2019_07_27_224818) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "locations", force: :cascade do |t|
    t.float "lat"
    t.float "lng"
    t.datetime "at"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer "vehicle_id"
  end

  create_table "vehicles", force: :cascade do |t|
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string "unique_id"
  end
end

Any help would be greatly appreciated!

Answer 1

It looks like the string d6880741-ae7f- .... is supposed to correspond to the unique_id column on vehicles. In which case you would use

@vehicle = Vehicle.find_by!(unique_id: params[:vehicle_id])

The id column is an int, and params[:vehicle_id] is a string ... thus Vehicle.find(params[:vehicle_id]) would always raise a "not found" error, which is the behavior you're seeing.

Note that find and find_by! will raise an error if the record is not found. If you don't want to have this happen, you can use find_by (without the exclamation point) - it just returns nil if the record is not found. But you will have to change your code to account for the possibility that @vehicle is nil.