Customize Model URLs with to_param

Rails models default to using their ID in URLs: /articles/42. The to_param method lets you customize this—use a slug, hide the ID, or combine both for readable URLs. Exposing IDs isn’t dangerous if you scope access properly, but you might want cleaner paths.

Instead of…

…exposing IDs in your URLs:

redirect_to article_path(@article)
# => "/articles/42"

Use…

…the to_param method to return a slug instead:

class Article < ApplicationRecord
  before_save { self.slug = title.parameterize }

  def to_param = slug
end

redirect_to article_path(@article)
# => "/articles/understanding-rails-extensions"

Then find records by slug in your controller:

def set_article
  @article = Article.find_by!(slug: params[:id])
end

For reliable lookups with readable URLs, prefix the slug with the ID:

def to_param
  "#{id}-#{title.parameterize}"
end

# => "/articles/42-understanding-rails-extensions"

The ID lookup just works—"42-understanding-rails-extensions".to_i returns 42, so Article.find(params[:id]) needs no parsing.

Why?

Rails URL helpers call to_param automatically when generating URLs. Override it to create cleaner, more descriptive paths without changing controller code.

Descriptive URLs are easier to read in logs, analytics, and when shared. They give users context about content before clicking. For content-heavy sites, slug-based URLs can help with SEO.

Hiding IDs also keeps URLs stable if you ever migrate databases or change ID schemes.

Why not?

Pure slug URLs require uniqueness on the relevant column, an index in the database, and method changes everywhere you find the model. If slugs can change, you’ll need redirects for old URLs.

For production apps, consider friendly_id—it handles slug generation, duplicates, history tracking, and scoped slugs. Or try prefixed_ids for Stripe-style encoded IDs like user_5vJjbzXq9KrLEMm32iAnOP0xGDYk6dpe that hide sequential IDs without needing slugs.

The ID-prefixed approach avoids uniqueness issues but still exposes the ID. Hiding IDs entirely means extra complexity in exchange for security through obscurity—a trade-off worth considering carefully.