CODEWITHSUNDEEP
ruby-on-railspostgresqlactiverecordforeign-keysjoin
brian-welch
brian-welch

Reputation: 461

Can someone find my syntax/logic error for 'unknown attribute' when creating seed method for a many to many join table in Rails?

The project is to build a web-app which I will use to log and track my strength training sessions. One of the tables/models is a join table linking exercises and trained bodyparts.

Here is the migration for the exercise table:

# migration: successfully creates the join table
class CreateExerciseBodyparts < ActiveRecord::Migration[5.2]
  def change
    create_table :exercise_bodyparts do |t|
      t.references :exercise, foreign_key: true
      t.references :bodypart, foreign_key: true
      t.timestamps
    end
  end
end

Here is the seed data for the table:

# seed data snippet: no syntax errors here
def exercise_bodyparts_list
  return [
    {
      name: "Barbell Back Squats",
      bodyparts: ["Quads","Hamstrings","Adductors","Abductors","Glutes","Lower Back","Abs"]
    },
    {
      name: "Barbell Biceps Curls ~0°",
      bodyparts: ["Biceps","Forearms"]
    },
    {
      name: "Barbell Biceps Curls ~45°",
      bodyparts: ["Biceps","Forearms"]
    },
    #(...)
  ]
end

Here is my seed method to populate the DB:

# seed method: where the error comes...
exercise_bodyparts_list.each do |ex_body|
  ex_body[:bodyparts].each do |bodypart|
    ExerciseBodypart.create!(
      exercise: Exercise.find_by_name(ex_body[:name]),
      bodypart: Bodypart.find_by_name(bodypart)
      )
  end
end

Here is the error message:

# error message:
ActiveModel::UnknownAttributeError: unknown attribute 'exercise' for ExerciseBodypart.

Upvotes: 0

Views: 35

Answers (2)

brian-welch
brian-welch

Reputation: 461

I received advice from another Ruby developer who said that I ought to be naming the relationship nature in the model with belongs_to

I indeed did that and the logic works ok.

My model looks like this:

class ExerciseBodypart < ApplicationRecord
  belongs_to :exercise
  belongs_to :bodypart
end

Lo and behold, this was the key. This espressed relationship in the model doesn't exist in my other project; however I suspect that the relationship is taken from the connection of other models - as it is a more complicated database with many more models.

Upvotes: 0

ray
ray

Reputation: 5552

I do not know exact reason but it was working for me inside rake task in rails-3 but failed for rails-5 while updating application to higher version.

I suggest you try following, following worked for me,

exercise_id: Exercise.find_by_name(ex_body[:name]).id

Upvotes: 1

Related Questions