Merge pull request rmosolgo#1869 from goco-inc/prepare-input-objects

Prepare input objects

Author: Robert Mosolgo

guides/type_definitions/input_objects.md

@@ -103,3 +103,30 @@ You can also add or override methods on input object classes to customize them.
 - `@context`: The current {{ "GraphQL::Query::Context" | api_doc }}
 
 Any extra methods you define on the class can be used for field resolution, as demonstrated above.
+
+## Converting to Other Ruby Objects
+
+Your input objects can be automatically converted to other Ruby types before they're passed to your application code. This is an easy way to use `Range`'s in your schema:
+
+```ruby
+class Types::DateRangeInput < Types::BaseInputObject
+  description "Range of dates"
+  argument :min, Types::Date, "Minimum value of the range", required: true
+  argument :max, Types::Date, "Maximum value of the range", required: true
+
+  def prepare
+    min..max
+  end
+end
+
+class Types::CalendarType < Types::BaseObject
+  field :appointments, [Types::Appointment], "Appointments on your calendar", null: false do
+    argument :during, Types::DateRangeInput, "Only show appointments within this range", required: true
+  end
+
+  def appointments(during:)
+    # during will be an instance of Range
+    object.appointments.select { |appointment| during.cover?(appointment.date) }
+  end
+end
+```

lib/graphql/input_object_type.rb

@@ -99,7 +99,8 @@ def coerce_non_null_input(value, ctx)
         end
       end
 
-      arguments_class.new(input_values, context: ctx, defaults_used: defaults_used)
+      result = arguments_class.new(input_values, context: ctx, defaults_used: defaults_used)
+      result.prepare
     end
 
     # @api private

lib/graphql/query/arguments.rb

@@ -87,6 +87,10 @@ def to_h
 
       def_delegators :to_h, :keys, :values, :each, :any?
 
+      def prepare
+        self
+      end
+
       # Access each key, value and type for the arguments in this set.
       # @yield [argument_value] The {ArgumentValue} for each argument
       # @yieldparam argument_value [ArgumentValue]
@@ -152,7 +156,8 @@ def wrap_value(value, arg_defn_type, context)
             wrap_value(value, arg_defn_type.of_type, context)
           when GraphQL::InputObjectType
             if value.is_a?(Hash)
-              arg_defn_type.arguments_class.new(value, context: context, defaults_used: Set.new)
+              result = arg_defn_type.arguments_class.new(value, context: context, defaults_used: Set.new)
+              result.prepare
             else
               value
             end

lib/graphql/query/literal_input.rb

@@ -108,7 +108,8 @@ def self.from_arguments(ast_arguments, argument_owner, variables)
           end
         end
 
-        argument_owner.arguments_class.new(values_hash, context: context, defaults_used: defaults_used)
+        result = argument_owner.arguments_class.new(values_hash, context: context, defaults_used: defaults_used)
+        result.prepare
       end
     end
   end

lib/graphql/schema/input_object.rb

@@ -57,6 +57,10 @@ def to_hash
         to_h
       end
 
+      def prepare
+        self
+      end
+
       def unwrap_value(value)
         case value
         when Array

spec/graphql/schema/input_object_spec.rb

@@ -168,6 +168,53 @@ def self.resolve_type(type, obj, ctx)
     end
   end
 
+  describe "prepare (entire input object)" do
+    module InputObjectPrepareObjectTest
+      class InputObj < GraphQL::Schema::InputObject
+        argument :min, Integer, required: true
+        argument :max, Integer, required: false
+
+        def prepare
+          min..max
+        end
+      end
+
+      class Query < GraphQL::Schema::Object
+        field :inputs, String, null: false do
+          argument :input, InputObj, required: true
+        end
+
+        def inputs(input:)
+          input.inspect
+        end
+      end
+
+      class Schema < GraphQL::Schema
+        query(Query)
+      end
+    end
+
+    it "calls prepare on the input object (literal)" do
+      query_str = <<-GRAPHQL
+      { inputs(input: { min: 5, max: 10 }) }
+      GRAPHQL
+
+      res = InputObjectPrepareObjectTest::Schema.execute(query_str)
+      expected_obj = (5..10).inspect
+      assert_equal expected_obj, res["data"]["inputs"]
+    end
+
+    it "calls prepare on the input object (variable)" do
+      query_str = <<-GRAPHQL
+      query ($input: InputObj!){ inputs(input: $input) }
+      GRAPHQL
+
+      res = InputObjectPrepareObjectTest::Schema.execute(query_str, variables: { input: { min: 5, max: 10 } })
+      expected_obj = (5..10).inspect
+      assert_equal expected_obj, res["data"]["inputs"]
+    end    
+  end
+
   describe "loading application object(s)" do
     module InputObjectLoadsTest
       class SingleLoadInputObj < GraphQL::Schema::InputObject