Rails4 Friendly_id Unique Slug Formatting

Question

I am using friendly_id gem for slugging my models. Since the slug has to be unique when i enter the same data to check i get a long hashed appending in the slug.

Answer 1

Today I came accross this issue and while other answer helped me get started, I wasn't satisfied because, like you, I wanted to have the slugs appear in sequence like explore, explore-2, explore-3.

So, here's how I fixed it:

class Thing < ActiveRecord::Base
  extend FriendlyId
  friendly_id :slug_candidates, use: :slugged

  validates :name, presence: true, uniqueness: { case_sensitive: false }
  validates :slug, uniqueness: true

  def slug_candidates
    [:name, [:name, :id_for_slug]]
  end

  def id_for_slug
    generated_slug = normalize_friendly_id(name)
    things = self.class.where('slug REGEXP :pattern', pattern: "#{generated_slug}(-[0-9]+)?$")
    things = things.where.not(id: id) unless new_record?
    things.count + 1
  end

  def should_generate_new_friendly_id?
    name_changed? || super
  end
end

I used uniqueness validation for :slug just in case this model is being used in concurrent code.

Here you can see it working:

irb(main):001:0> Thing.create(name: 'New thing')
   (0.1ms)  begin transaction
   (0.2ms)  SELECT COUNT(*) FROM "things" WHERE (slug REGEXP 'new-thing(-[0-9]+)?$')
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing"]]
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE LOWER("things"."name") = LOWER('New thing') LIMIT 1
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE "things"."slug" = 'new-thing' LIMIT 1
  SQL (0.4ms)  INSERT INTO "things" ("name", "slug") VALUES (?, ?)  [["name", "New thing"], ["slug", "new-thing"]]
   (115.7ms)  commit transaction
=> #
irb(main):002:0> Thing.create(name: 'New thing')
   (0.2ms)  begin transaction
   (0.9ms)  SELECT COUNT(*) FROM "things" WHERE (slug REGEXP 'new-thing(-[0-9]+)?$')
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing"]]
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing-2"]]
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE LOWER("things"."name") = LOWER('New thing') LIMIT 1
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE "things"."slug" = 'new-thing-2' LIMIT 1
   (0.1ms)  rollback transaction
=> #
irb(main):003:0> Thing.create(name: 'New-thing')
   (0.2ms)  begin transaction
   (0.5ms)  SELECT COUNT(*) FROM "things" WHERE (slug REGEXP 'new-thing(-[0-9]+)?$')
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing"]]
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing-2"]]
  Thing Exists (0.3ms)  SELECT  1 AS one FROM "things" WHERE LOWER("things"."name") = LOWER('New-thing') LIMIT 1
  Thing Exists (0.3ms)  SELECT  1 AS one FROM "things" WHERE "things"."slug" = 'new-thing-2' LIMIT 1
  SQL (0.4ms)  INSERT INTO "things" ("name", "slug") VALUES (?, ?)  [["name", "New-thing"], ["slug", "new-thing-2"]]
   (108.9ms)  commit transaction
=> #
irb(main):004:0> Thing.create(name: 'New!thing')
   (0.2ms)  begin transaction
   (0.6ms)  SELECT COUNT(*) FROM "things" WHERE (slug REGEXP 'new-thing(-[0-9]+)?$')
  Thing Exists (0.0ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing"]]
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE ("things"."id" IS NOT NULL) AND "things"."slug" = ? LIMIT 1  [["slug", "new-thing-3"]]
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE LOWER("things"."name") = LOWER('New!thing') LIMIT 1
  Thing Exists (0.1ms)  SELECT  1 AS one FROM "things" WHERE "things"."slug" = 'new-thing-3' LIMIT 1
  SQL (0.1ms)  INSERT INTO "things" ("name", "slug") VALUES (?, ?)  [["name", "New!thing"], ["slug", "new-thing-3"]]
   (112.4ms)  commit transaction
=> #
irb(main):005:0> 

Also, if you use sqlite3 adapter you'll need to install sqlite3_ar_regexp gem (it won't be very fast, because SQLite doesn't have REGEXP() and it evaluates Ruby code instead).