Blueprints

A blueprint specifies how to construct an object of a class by providing values for its attributes.

Post.blueprint do
  title { "A Post" }
  body  { "Lorem ipsum..." }
end

Serial Numbers

If you’ve got an attribute that needs to be unique, Machinist gives you a serial number for the object being created that you can insert into the attribute.

User.blueprint do
  username { "user#{sn}" }
end

Learn more about Serial Numbers.

Accessing Other Attributes

You can access the object being constructed from within your blueprints, so you can construct one attribute from another.

User.blueprint do
  username { "user#{sn}" }
  email    { "#{object.username}@example.com" }
end

Associations

Machinist knows about ActiveRecord associations, and will automatically generate associated objects.

Comment.blueprint do
  post # This will look at the post association, and make the right kind of object.
end

Learn more about Associations.

Inheritance

Machinist knows about object inheritance, and will apply blueprints from parent classes.

ParentClass.blueprint do
  name { "Fred" }
  age  { 97 }
end

ChildClass.blueprint do
  # The blueprint will take the name attribute from ParentClass's blueprint.
  age { 36 }  # This will override the age from ParentClass.
end

Learn more about Inheritance.

Named Blueprints

You can create different, named blueprints for a class.

Comment.blueprint(:spam) do
  spam { true }
  body { "Send me money!" }
end

Comment.make(:spam)

Learn more about Named Blueprints.