Friendly ID - undefined method `slug=' for

Question

I am using the gems Workflow, Paper Trail and Friend ID.

To track the state changes using Paper Trail, I have overridden the persist_workflow_state to explicitly update the workflow column, so that Paper Trail can capture the change.

https://github.com/geekq/workflow#integration-with-activerecord

def persist_workflow_state(new_value)
  update_attribute self.class.workflow_column, new_value
end

Now, I have introduced Friendly ID without slug column, and I get the error, upon reaching the above method.

undefined method `slug=' for #<ModelName:0x007f81cf342cd8>

Any help?

Answer 1

Basic point is that, if you're using the friendly ID gem, then you will need to add a slug column, to the relevant ActiveModel table.

Example: Add a slug to my Project model

Each Project has a name (attribute).

class Project < ApplicationRecord
      extend FriendlyId
      friendly_id :name, use: :slugged        

      validates :name, :state, presence: true
end

1. Run a migration to add a slug column

This can be done easily in rails:

 rails g migration AddSlugToProjects slug

2. Don't forget the index!:

Make sure you add in an index on the slug column:

class AddSlugToProjects < ActiveRecord::Migration[5.2]
  def change
    add_column :projects, :slug, :string
    add_index :projects, :slug
  end
end

And now you're off to the races!

Answer 2

Now, I have introduced Friendly ID without slug column

I don't know exactly what you mean here, but simply, it's like trying to start a car without the key

---

FriendlyID

The way FriendlyID works is to use a slug (or other identifier) column to both create the slugged URL, and find based off the slugged ID:

extend FriendlyId
friendly_id :name, use: [:slugged, :finders]

This allows the gem to find based off either the id or the slug attribute

If you miss out the slug column, this will prevent this from working, causing your error. The ways to fix this are:

1. Use the slug column
2. Create a slug attribute using attr_accessor

If you'd like to try the second option, you could try this:

#app/models/ModelName.rb
attr_accessor :slug

Answer 3

Richard Peck is correct that you have to add slug field.

But lot's of people got confused because FriendlyID generates friendly_id_slugs table which contains sluggable_id and sluggable_type field.

create_table "friendly_id_slugs", force: :cascade do |t|
t.string   "slug",                      null: false
t.integer  "sluggable_id",              null: false
t.string   "sluggable_type", limit: 50
t.string   "scope"
t.datetime "created_at"
t.index ["slug", "sluggable_type", "scope"], name: "index_friendly_id_slugs_on_slug_and_sluggable_type_and_scope", unique: true
t.index ["slug", "sluggable_type"], name: "index_friendly_id_slugs_on_slug_and_sluggable_type"
t.index ["sluggable_id"], name: "index_friendly_id_slugs_on_sluggable_id"
t.index ["sluggable_type"], name: "index_friendly_id_slugs_on_sluggable_type"
end

Basically it generates friendly_id_slugs table for History Module. Have a look at their documentation about History__Avoiding_404_s_When_Slugs_Change : http://norman.github.io/friendly_id/file.Guide.html#History__Avoiding_404_s_When_Slugs_Change