Command plugin to accept input with aliased keys

core/lib/rom/core.rb

@@ -33,6 +33,7 @@
 require 'rom/plugins/relation/instrumentation'
 require 'rom/plugins/command/schema'
 require 'rom/plugins/command/timestamps'
+require 'rom/plugins/command/alias'
 require 'rom/plugins/schema/timestamps'
 
 module ROM
@@ -45,5 +46,6 @@ module ROM
     register :instrumentation, ROM::Plugins::Relation::Instrumentation, type: :relation
     register :schema, ROM::Plugins::Command::Schema, type: :command
     register :timestamps, ROM::Plugins::Command::Timestamps, type: :command
+    register :alias, ROM::Plugins::Command::Alias, type: :command
   end
 end

core/lib/rom/plugins/command/alias.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module ROM
+  module Plugins
+    module Command
+      # A plugin for transparently translating schema defined aliases
+      # into canonical names expected by adapters.
+      #
+      # @example
+      #   class User < ROM::Relations[:sql]
+      #     schema(infer: true) do
+      #       attribute :first_name, alias: name
+      #     end
+      #   end
+      #
+      #   class CreateUser < ROM::Commands::Create[:sql]
+      #     result :one
+      #     use :alias
+      #   end
+      #
+      #   result = rom.command(:user).create.call(name: 'Jane')
+      #   result[:first_name]  #=> 'Jane'
+      #
+      # @api public
+      module Alias
+        module T
+          extend Transproc::Registry
+
+          import :rename_keys, from: Transproc::HashTransformations
+        end
+
+        # @api private
+        def self.included(klass)
+          super
+          klass.before :map_aliases
+          klass.include(InstanceMethods)
+        end
+
+        module InstanceMethods
+          # @api private
+          def map_aliases(tuples, *)
+            mapping = relation.class.schema.alias_mapping.invert
+            map_input_tuples(tuples) do |t|
+              T[:rename_keys].(t, mapping)
+            end
+          end
+        end
+      end
+    end
+  end
+end

core/lib/rom/schema.rb

@@ -450,6 +450,17 @@ def to_ast
       [:schema, [name, attributes.map(&:to_ast)]]
     end
 
+    # Hash from canonical name to alias for aliased attributes
+    #
+    # @return [Hash<Symbol, Symbol>]
+    #
+    # @api public
+    def alias_mapping
+      each_with_object({}) do |attr, obj|
+        obj[attr.name] = attr.alias if attr.aliased?
+      end
+    end
+
     # @api private
     def set!(key, value)
       instance_variable_set("@#{ key }", value)

core/spec/unit/rom/plugins/command/alias_spec.rb

@@ -0,0 +1,36 @@
+require 'rom/command'
+require 'rom/plugins/command/alias'
+
+RSpec.describe ROM::Plugins::Command::Alias do
+  include_context 'container'
+
+  let(:users) { container.commands.users }
+  let(:command) { users.create }
+
+  before do
+    configuration.relation :users do
+      schema(:users) do
+        attribute :first_name, Types::String, alias: :name
+      end
+    end
+
+    configuration.commands(:users) do
+      define :create, type: :create do
+        result :one
+        use :alias
+      end
+    end
+  end
+
+  it 'accepts input with aliased names' do
+    result = command.call(name: 'Joe')
+
+    expect(result[:first_name]).to eq('Joe')
+  end
+
+  it 'accepts input with canonical names' do
+    result = command.call(first_name: 'Joe')
+
+    expect(result[:first_name]).to eq('Joe')
+  end
+end

core/spec/unit/rom/schema_spec.rb

@@ -67,4 +67,16 @@
       expect(schema.project(:name).primary_key_name).to be(:id)
     end
   end
+
+  describe '#alias_mapping' do
+    it 'returns a hash from canonical name to alias including aliased attributes' do
+      attrs = [
+        define_attr_info(:Integer, name: :id, alias: :pk),
+        define_attr_info(:String, name: :name)
+      ]
+      schema = ROM::Schema.define(:name, attributes: attrs)
+
+      expect(schema.alias_mapping).to eq(id: :pk)
+    end
+  end
 end