dynamic_routes.cr

require "json"
require "kemal"

macro build_routes(hash)
  {% for route, info in hash %}
  {{info[:method].id}} {{route}} do |env|
      # originally I had info[:method] but that would kick out "put"
      # but changing to info[:method].id kicked out put, which worked.
    env.response.status_code = {{info[:status_code]}}
    env.response.content_type = "application/json"
    {{info[:body]}}.to_json
  end
  {% end %}
end

build_routes({
  "/widgets/:widget_id" => {
      :method => "put",
      :status_code => 200,
      :body => {foo: 1},
  }
})

Kemal.run

I tried doing

routes = {
  "/widgets/:widget_id" => {
      :method => "put",
      :status_code => 200,
      :body => {foo: 1},
  }
}

build_routes(routes)

but I would get an error:

build_routes(routes)
^~~~~~~~~~~~

in ./src/mock_api.cr:8: for expression must be an array, hash or tuple literal, not Var:

routes

  {% for route, info in hash %}

I don't know enough about how the type system works in Crystal. Thoughts?

You're creating routes as a local variable at runtime. Needs to be a literal to be evaluated at compile-time.

Ah, that makes sense. I ended up getting rid of that var anyway.