Reflection

The V2 Reflection API has very few changes from Legacy/V1.

Reflecting on fields

Regular fields (no change):

MyBlueprint.reflections[:default].fields

Objects and collections:

# Legacy/V1 does not differentiate between objects and collections
MyV1Blueprint.reflections[:default].associations

# V2 does
MyV2Blueprint.reflections[:default].objects
MyV2Blueprint.reflections[:default].collections

Field names

V2’s field metadata is similar, but there’s an important different in name.

Legacy/V1

In Legacy/V1, name refers to what the field is called in the input.

class MyV1Blueprint < Blueprinter::Base
  field :foo, name: :bar
end

ref = MyV1Blueprint.reflections[:default]

# What the field is called in the source object
ref.fields[:foo].name
=> :foo

# What the field will be called in the output
ref.fields[:foo].display_name
=> :bar

V2

In V2, name refers to what the field is called in the output. Note that this change is also reflected in the Hash key.

class MyV2Blueprint < Blueprinter::Blueprint
  field :bar, from: :foo
end

ref = MyV1Blueprint.reflections[:default]

# What the field will be called in the output
ref.fields[:bar].name
=> :bar

# What the field is called in the source object
ref.fields[:bar].from
=> :foo