Coerce collections of parseable types

CHANGELOG.md

@@ -5,6 +5,7 @@
 * [#1686](https://github.com/ruby-grape/grape/pull/1686): Avoid coercion of a value if it is valid - [@timothysu](https://github.com/timothysu).
 * [#1688](https://github.com/ruby-grape/grape/pull/1688): Removes yard docs - [@ramkumar-kr](https://github.com/ramkumar-kr).
 * [#1702](https://github.com/ruby-grape/grape/pull/1702): Added danger-toc, verify correct TOC in README - [@dblock](https://github.com/dblock).
+* [#1711](https://github.com/ruby-grape/grape/pull/1711): Automatically coerce arrays and sets of types that implement a `parse` method - [@dslh](https://github.com/dslh).
 
 #### Fixes
 

README.md

@@ -909,6 +909,8 @@ end
 
 params do
   requires :color, type: Color, default: Color.new('blue')
+  requires :more_colors, type: Array[Color] # Collections work
+  optional :unique_colors, type: Set[Color] # Duplicates discarded
 end
 
 get '/stuff' do
@@ -943,6 +945,26 @@ params do
 end
 ```
 
+Grape will assert that coerced values match the given `type`, and will reject the request
+if they do not. To override this behaviour, custom types may implement a `parsed?` method
+that should accept a single argument and return `true` if the value passes type validation.
+
+```ruby
+class SecureUri
+  def self.parse(value)
+    URI.parse value
+  end
+
+  def self.parsed?(value)
+    value.is_a? URI::HTTPS
+  end
+end
+
+params do
+  requires :secure_uri, type: SecureUri
+end
+```
+
 ### Multipart File Parameters
 
 Grape makes use of `Rack::Request`'s built-in support for multipart file parameters. Such parameters can be declared with `type: File`:

lib/grape/validations/types.rb

@@ -1,5 +1,6 @@
 require_relative 'types/build_coercer'
 require_relative 'types/custom_type_coercer'
+require_relative 'types/custom_type_collection_coercer'
 require_relative 'types/multiple_type_coercer'
 require_relative 'types/variant_collection_coercer'
 require_relative 'types/json'
@@ -143,7 +144,8 @@ def self.group?(type)
       end
 
       # A valid custom type must implement a class-level `parse` method, taking
-      #   one String argument and returning the parsed value in its correct type.
+      # one String argument and returning the parsed value in its correct type.
+      #
       # @param type [Class] type to check
       # @return [Boolean] whether or not the type can be used as a custom type
       def self.custom?(type)
@@ -155,6 +157,17 @@ def self.custom?(type)
           type.respond_to?(:parse) &&
           type.method(:parse).arity == 1
       end
+
+      # Is the declared type an +Array+ or +Set+ of a {#custom?} type?
+      #
+      # @param type [Array<Class>,Class] type to check
+      # @return [Boolean] true if +type+ is a collection of a type that implements
+      #   its own +#parse+ method.
+      def self.collection_of_custom?(type)
+        (type.is_a?(Array) || type.is_a?(Set)) &&
+          type.length == 1 &&
+          custom?(type.first)
+      end
     end
   end
 end

lib/grape/validations/types/build_coercer.rb

@@ -51,6 +51,14 @@ def self.create_coercer_instance(type, method = nil)
         elsif method || Types.custom?(type)
           converter_options[:coercer] = Types::CustomTypeCoercer.new(type, method)
 
+        # Special coercer for collections of types that implement a parse method.
+        # CustomTypeCoercer (above) already handles such types when an explicit coercion
+        # method is supplied.
+        elsif Types.collection_of_custom?(type)
+          converter_options[:coercer] = Types::CustomTypeCollectionCoercer.new(
+            type.first, type.is_a?(Set)
+          )
+
         # Grape swaps in its own Virtus::Attribute implementations
         # for certain special types that merit first-class support
         # (but not if a custom coercion method has been supplied).

lib/grape/validations/types/custom_type_collection_coercer.rb

@@ -0,0 +1,71 @@
+module Grape
+  module Validations
+    module Types
+      # Instances of this class may be passed to
+      # +Virtus::Attribute.build+ as the +:coercer+
+      # option, to handle collections of types that
+      # provide their own parsing (and optionally,
+      # type-checking) functionality.
+      #
+      # See {CustomTypeCoercer} for details on types
+      # that will be supported by this by this coercer.
+      # This coercer works in the same way as +CustomTypeCoercer+
+      # except that it expects to receive an array of strings to
+      # coerce and will return an array (or optionally, a set)
+      # of coerced values.
+      #
+      # +CustomTypeCoercer+ is already capable of providing type
+      # checking for arrays where an independent coercion method
+      # is supplied. As such, +CustomTypeCollectionCoercer+ does
+      # not allow for such a method to be supplied independently
+      # of the type.
+      class CustomTypeCollectionCoercer < CustomTypeCoercer
+        # A new coercer for collections of the given type.
+        #
+        # @param type [Class,#parse]
+        #   type to which items in the array should be coerced.
+        #   Must implement a +parse+ method which accepts a string,
+        #   and for the purposes of type-checking it may either be
+        #   a class, or it may implement a +coerced?+, +parsed?+ or
+        #   +call+ method (in that order of precedence) which
+        #   accepts a single argument and returns true if the given
+        #   array item has been coerced correctly.
+        # @param set [Boolean]
+        #   when true, a +Set+ will be returned by {#call} instead
+        #   of an +Array+ and duplicate items will be discarded.
+        def initialize(type, set = false)
+          super(type)
+          @set = set
+        end
+
+        # This method is called from somewhere within
+        # +Virtus::Attribute::coerce+ in order to coerce
+        # the given value.
+        #
+        # @param value [Array<String>] an array of values to be coerced
+        # @return [Array,Set] the coerced result. May be an +Array+ or a
+        #   +Set+ depending on the setting given to the constructor
+        def call(value)
+          coerced = value.map { |item| super(item) }
+
+          @set ? Set.new(coerced) : coerced
+        end
+
+        # This method is called from somewhere within
+        # +Virtus::Attribute::value_coerced?+ in order to assert
+        # that the all of the values in the array have been coerced
+        # successfully.
+        #
+        # @param primitive [Axiom::Types::Type] primitive type for
+        #   the coercion as deteced by axiom-types' inference system.
+        # @param value [Enumerable] a coerced result returned from {#call}
+        # @return [true,false] whether or not all of the coerced values in
+        #   the collection satisfy type requirements.
+        def success?(primitive, value)
+          value.is_a?(@set ? Set : Array) &&
+            value.all? { |item| super(primitive, item) }
+        end
+      end
+    end
+  end
+end

spec/grape/validations/validators/coerce_spec.rb

@@ -225,6 +225,55 @@ class User
           expect(last_response.status).to eq(200)
           expect(last_response.body).to eq('1')
         end
+
+        it 'Array of type implementing parse' do
+          subject.params do
+            requires :uri, type: Array[URI]
+          end
+          subject.get '/uri_array' do
+            params[:uri][0].class
+          end
+          get 'uri_array', uri: ['http://www.google.com']
+          expect(last_response.status).to eq(200)
+          expect(last_response.body).to eq('URI::HTTP')
+        end
+
+        it 'Set of type implementing parse' do
+          subject.params do
+            requires :uri, type: Set[URI]
+          end
+          subject.get '/uri_array' do
+            "#{params[:uri].class},#{params[:uri].first.class},#{params[:uri].size}"
+          end
+          get 'uri_array', uri: Array.new(2) { 'http://www.example.com' }
+          expect(last_response.status).to eq(200)
+          expect(last_response.body).to eq('Set,URI::HTTP,1')
+        end
+
+        it 'Array of class implementing parse and parsed?' do
+          class SecureURIOnly
+            def self.parse(value)
+              URI.parse(value)
+            end
+
+            def self.parsed?(value)
+              value.is_a? URI::HTTPS
+            end
+          end
+
+          subject.params do
+            requires :uri, type: Array[SecureURIOnly]
+          end
+          subject.get '/secure_uris' do
+            params[:uri].first.class
+          end
+          get 'secure_uris', uri: ['https://www.example.com']
+          expect(last_response.status).to eq(200)
+          expect(last_response.body).to eq('URI::HTTPS')
+          get 'secure_uris', uri: ['https://www.example.com', 'http://www.example.com']
+          expect(last_response.status).to eq(400)
+          expect(last_response.body).to eq('uri is invalid')
+        end
       end
 
       context 'Set' do