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route_constraints_lambda

🚧 Leverage Route Constraints for Dynamic Matching​

Constraint lambdas give you programmatic control over whether a route matches. Use them to guard routes by subdomains, request params, or any custom logic.

# config/routes.rb
Rails.application.routes.draw do
  constraints(lambda { |req| req.params[:preview] == "true" }) do
    get 'articles/preview/:id', to: 'articles#preview'
  end
end

Here, the preview route only matches when ?preview=true is present. You can also define a custom constraint class for more complex checks.