Support for the Many-to-One association

lib/hanami/model/associations/belongs_to.rb

@@ -5,14 +5,95 @@ module Model
     module Associations
       # Many-To-One association
       #
-      # @since 0.7.0
+      # @since x.x.x
       # @api private
       class BelongsTo
-        # @since 0.7.0
+        # @since x.x.x
         # @api private
         def self.schema_type(entity)
           Sql::Types::Schema::AssociationType.new(entity)
         end
+
+        # @since x.x.x
+        # @api private
+        attr_reader :repository
+
+        # @since x.x.x
+        # @api private
+        attr_reader :source
+
+        # @since x.x.x
+        # @api private
+        attr_reader :target
+
+        # @since x.x.x
+        # @api private
+        attr_reader :subject
+
+        # @since x.x.x
+        # @api private
+        attr_reader :scope
+
+        # @since x.x.x
+        # @api private
+        def initialize(repository, source, target, subject, scope = nil)
+          @repository = repository
+          @source     = source
+          @target     = target
+          @subject    = subject.to_hash unless subject.nil?
+          @scope      = scope || _build_scope
+          freeze
+        end
+
+        # @since x.x.x
+        # @api private
+        def one
+          scope.one
+        end
+
+        private
+
+        # @since x.x.x
+        # @api private
+        def container
+          repository.container
+        end
+
+        # @since x.x.x
+        # @api private
+        def primary_key
+          association_keys.first
+        end
+
+        # @since x.x.x
+        # @api private
+        def relation(name)
+          repository.relations[Hanami::Utils::String.new(name).pluralize]
+        end
+
+        # @since x.x.x
+        # @api private
+        def foreign_key
+          association_keys.last
+        end
+
+        # Returns primary key and foreign key
+        #
+        # @since x.x.x
+        # @api private
+        def association_keys
+          relation(source)
+            .associations[target]
+            .__send__(:join_key_map, container.relations)
+        end
+
+        # @since x.x.x
+        # @api private
+        def _build_scope
+          result = relation(target)
+          result = result.where(foreign_key => subject.fetch(primary_key)) unless subject.nil?
+          result.as(Model::MappedRelation.mapper_name)
+        end
       end
     end
   end

lib/hanami/model/associations/dsl.rb

@@ -19,9 +19,10 @@ def has_many(relation, *)
           @repository.__send__(:relations, relation)
         end
 
-        # @since 0.7.0
+        # @since x.x.x
         # @api private
-        def belongs_to(*)
+        def belongs_to(relation, *)
+          @repository.__send__(:relations, Hanami::Utils::String.new(relation).pluralize.to_sym)
         end
       end
     end

lib/hanami/model/error.rb

@@ -60,7 +60,7 @@ def initialize(message = 'Constraint has been violated')
     # Error for Unique Constraint Violation
     #
     # @since 0.6.1
-    class UniqueConstraintViolationError < Error
+    class UniqueConstraintViolationError < ConstraintViolationError
       # @since 0.6.1
       # @api private
       def initialize(message = 'Unique constraint has been violated')
@@ -71,7 +71,7 @@ def initialize(message = 'Unique constraint has been violated')
     # Error for Foreign Key Constraint Violation
     #
     # @since 0.6.1
-    class ForeignKeyConstraintViolationError < Error
+    class ForeignKeyConstraintViolationError < ConstraintViolationError
       # @since 0.6.1
       # @api private
       def initialize(message = 'Foreign key constraint has been violated')
@@ -82,7 +82,7 @@ def initialize(message = 'Foreign key constraint has been violated')
     # Error for Not Null Constraint Violation
     #
     # @since 0.6.1
-    class NotNullConstraintViolationError < Error
+    class NotNullConstraintViolationError < ConstraintViolationError
       # @since 0.6.1
       # @api private
       def initialize(message = 'NOT NULL constraint has been violated')
@@ -93,7 +93,7 @@ def initialize(message = 'NOT NULL constraint has been violated')
     # Error for Check Constraint Violation raised by Sequel
     #
     # @since 0.6.1
-    class CheckConstraintViolationError < Error
+    class CheckConstraintViolationError < ConstraintViolationError
       # @since 0.6.1
       # @api private
       def initialize(message = 'Check constraint has been violated')

spec/integration/associations/belongs_to_spec.rb

@@ -0,0 +1,28 @@
+RSpec.describe 'Associations (belongs_To)' do
+  it "returns nil if association wasn't preloaded" do
+    repository = BookRepository.new
+    book       = repository.create(name: 'L')
+    found      = repository.find(book.id)
+
+    expect(found.author).to be(nil)
+  end
+
+  it 'preloads the associated record' do
+    repository = BookRepository.new
+    author = AuthorRepository.new.create(name: 'Michel Foucault')
+    book   = repository.create(author_id: author.id, title: 'Surveiller et punir')
+    found = repository.find_with_author(book.id)
+
+    expect(found).to eq(book)
+    expect(found.author).to eq(author)
+  end
+
+  it 'returns an author' do
+    repository = BookRepository.new
+    author = AuthorRepository.new.create(name: 'Maurice Leblanc')
+    book   = repository.create(author_id: author.id, title: "L'Aguille Creuse")
+    found = repository.author_for(book)
+
+    expect(found).to eq(author)
+  end
+end

spec/support/fixtures.rb

@@ -138,6 +138,14 @@ class BookRepository < Hanami::Repository
   associations do
     belongs_to :author
   end
+
+  def find_with_author(id)
+    aggregate(:author).where(id: id).as(Book).one
+  end
+
+  def author_for(book)
+    assoc(:author, book).one
+  end
 end
 
 class OperatorRepository < Hanami::Repository

spec/unit/hanami/model/check_constraint_validation_error_spec.rb

@@ -0,0 +1,13 @@
+RSpec.describe Hanami::Model::CheckConstraintViolationError do
+  it "inherits from Hanami::Model::ConstraintViolationError" do
+    expect(described_class.ancestors).to include(Hanami::Model::ConstraintViolationError)
+  end
+
+  it "has a default error message" do
+    expect { raise described_class }.to raise_error(described_class, "Check constraint has been violated")
+  end
+
+  it "allows custom error message" do
+    expect { raise described_class.new("Ouch") }.to raise_error(described_class, "Ouch")
+  end
+end

spec/unit/hanami/model/constraint_violation_error_spec.rb

@@ -0,0 +1,13 @@
+RSpec.describe Hanami::Model::ConstraintViolationError do
+  it "inherits from Hanami::Model::Error" do
+    expect(described_class.ancestors).to include(Hanami::Model::Error)
+  end
+
+  it "has a default error message" do
+    expect { raise described_class }.to raise_error(described_class, "Constraint has been violated")
+  end
+
+  it "allows custom error message" do
+    expect { raise described_class.new("Ouch") }.to raise_error(described_class, "Ouch")
+  end
+end

spec/unit/hanami/model/error_spec.rb

@@ -0,0 +1,5 @@
+RSpec.describe Hanami::Model::Error do
+  it "inherits from StandardError" do
+    expect(described_class.ancestors).to include(StandardError)
+  end
+end

spec/unit/hanami/model/foreign_key_constraint_violation_error_spec.rb

@@ -0,0 +1,13 @@
+RSpec.describe Hanami::Model::ForeignKeyConstraintViolationError do
+  it "inherits from Hanami::Model::ConstraintViolationError" do
+    expect(described_class.ancestors).to include(Hanami::Model::ConstraintViolationError)
+  end
+
+  it "has a default error message" do
+    expect { raise described_class }.to raise_error(described_class, "Foreign key constraint has been violated")
+  end
+
+  it "allows custom error message" do
+    expect { raise described_class.new("Ouch") }.to raise_error(described_class, "Ouch")
+  end
+end

spec/unit/hanami/model/not_null_constraint_violation_error_spec.rb

@@ -0,0 +1,13 @@
+RSpec.describe Hanami::Model::NotNullConstraintViolationError do
+  it "inherits from Hanami::Model::ConstraintViolationError" do
+    expect(described_class.ancestors).to include(Hanami::Model::ConstraintViolationError)
+  end
+
+  it "has a default error message" do
+    expect { raise described_class }.to raise_error(described_class, "NOT NULL constraint has been violated")
+  end
+
+  it "allows custom error message" do
+    expect { raise described_class.new("Ouch") }.to raise_error(described_class, "Ouch")
+  end
+end

spec/unit/hanami/model/unique_constraint_violation_error_spec.rb

@@ -0,0 +1,13 @@
+RSpec.describe Hanami::Model::UniqueConstraintViolationError do
+  it "inherits from Hanami::Model::ConstraintViolationError" do
+    expect(described_class.ancestors).to include(Hanami::Model::ConstraintViolationError)
+  end
+
+  it "has a default error message" do
+    expect { raise described_class }.to raise_error(described_class, "Unique constraint has been violated")
+  end
+
+  it "allows custom error message" do
+    expect { raise described_class.new("Ouch") }.to raise_error(described_class, "Ouch")
+  end
+end