Features/inheritance and discriminator (#793)

* Add Discrimator

* Fix rubocop and add test

* Add Changelog

* Fix spec_helper and move test

* Add Readme

* Point grape-swagger-entity to rubygems again

* Force new test

* Fix rubocop

Co-authored-by: peter scholz <pscholz.le@gmail.com>

CHANGELOG.md

@@ -3,6 +3,7 @@
 #### Features
 
 * Your contribution here.
+* [#793](https://github.com/ruby-grape/grape-swagger/pull/793): Features/inheritance and discriminator - [@MaximeRDY](https://github.com/MaximeRDY).
 
 #### Fixes
 

README.md

@@ -44,15 +44,15 @@ This screenshot is based on the [Hussars](https://github.com/LeFnord/hussars) sa
 The following versions of grape, grape-entity and grape-swagger can currently be used together.
 
 | grape-swagger | swagger spec | grape                   | grape-entity | representable |
-|---------------|--------------|-------------------------|--------------|---------------|
-| 0.10.5        |     1.2      | >= 0.10.0 ... <= 0.14.0 |  < 0.5.0     | n/a           |
-| 0.11.0        |     1.2      |               >= 0.16.2 |  < 0.5.0     | n/a           |
-| 0.25.2        |     2.0      | >= 0.14.0 ... <= 0.18.0 | <= 0.6.0     | >= 2.4.1      |
-| 0.26.0        |     2.0      | >= 0.16.2 ... <= 1.1.0  | <= 0.6.1     | >= 2.4.1      |
-| 0.27.0        |     2.0      | >= 0.16.2 ... <= 1.1.0  | >= 0.5.0     | >= 2.4.1      |
-| 0.32.0        |     2.0      | >= 0.16.2               | >= 0.5.0     | >= 2.4.1      |
-| 0.34.0        |     2.0      | >= 0.16.2 ... < 1.3.0   | >= 0.5.0     | >= 2.4.1      |
-| >= 1.0.0      |     2.0      | >= 1.3.0                | >= 0.5.0     | >= 2.4.1      |
+| ------------- | ------------ | ----------------------- | ------------ | ------------- |
+| 0.10.5        | 1.2          | >= 0.10.0 ... <= 0.14.0 | < 0.5.0      | n/a           |
+| 0.11.0        | 1.2          | >= 0.16.2               | < 0.5.0      | n/a           |
+| 0.25.2        | 2.0          | >= 0.14.0 ... <= 0.18.0 | <= 0.6.0     | >= 2.4.1      |
+| 0.26.0        | 2.0          | >= 0.16.2 ... <= 1.1.0  | <= 0.6.1     | >= 2.4.1      |
+| 0.27.0        | 2.0          | >= 0.16.2 ... <= 1.1.0  | >= 0.5.0     | >= 2.4.1      |
+| 0.32.0        | 2.0          | >= 0.16.2               | >= 0.5.0     | >= 2.4.1      |
+| 0.34.0        | 2.0          | >= 0.16.2 ... < 1.3.0   | >= 0.5.0     | >= 2.4.1      |
+| >= 1.0.0      | 2.0          | >= 1.3.0                | >= 0.5.0     | >= 2.4.1      |
 
 
 ## Swagger-Spec <a name="swagger-spec"></a>
@@ -1381,6 +1381,94 @@ module API
 end
 ```
 
+#### Inheritance with allOf and discriminator
+```ruby
+module Entities
+  class Pet < Grape::Entity
+    expose :type, documentation: {
+      type: 'string',
+      is_discriminator: true,
+      required: true
+    }
+    expose :name, documentation: {
+      type: 'string',
+      required: true
+    }
+  end
+
+  class Cat < Pet
+    expose :huntingSkill, documentation: {
+      type: 'string',
+      description: 'The measured skill for hunting',
+      default: 'lazy',
+      values: %w[
+        clueless
+        lazy
+        adventurous
+        aggressive
+      ]
+    }
+  end
+end
+```
+
+Should generate this definitions:
+```JSON
+{
+  "definitions": {
+    "Pet": {
+      "type": "object",
+      "discriminator": "petType",
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "petType": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "name",
+        "petType"
+      ]
+    },
+    "Cat": {
+      "description": "A representation of a cat",
+      "allOf": [
+        {
+          "$ref": "#/definitions/Pet"
+        },
+        {
+          "type": "object",
+          "properties": {
+            "huntingSkill": {
+              "type": "string",
+              "description": "The measured skill for hunting",
+              "default": "lazy",
+              "enum": [
+                "clueless",
+                "lazy",
+                "adventurous",
+                "aggressive"
+              ]
+            },
+            "petType": {
+              "type": "string",
+              "enum": ["Cat"]
+            }
+          },
+          "required": [
+            "huntingSkill",
+            "petType"
+          ]
+        }
+      ]
+    }
+  }
+}
+```
+
+
 
 
 ## Securing the Swagger UI <a name="oauth"></a>

lib/grape-swagger/doc_methods/build_model_definition.rb

@@ -4,8 +4,8 @@ module GrapeSwagger
   module DocMethods
     class BuildModelDefinition
       class << self
-        def build(model, properties, required)
-          definition = { type: 'object', properties: properties }
+        def build(model, properties, required, other_def_properties = {})
+          definition = { type: 'object', properties: properties }.merge(other_def_properties)
 
           if required.nil?
             required_attrs = required_attributes(model)
@@ -17,6 +17,57 @@ def build(model, properties, required)
           definition
         end
 
+        def parse_params_from_model(parsed_response, model, model_name)
+          if parsed_response.is_a?(Hash) && parsed_response.keys.first == :allOf
+            refs_or_models = parsed_response[:allOf]
+            parsed = parse_refs_and_models(refs_or_models, model)
+
+            {
+              allOf: parsed
+            }
+          else
+            properties, required = parsed_response
+            unless properties&.any?
+              raise GrapeSwagger::Errors::SwaggerSpec,
+                    "Empty model #{model_name}, swagger 2.0 doesn't support empty definitions."
+            end
+            properties, other_def_properties = parse_properties(properties)
+
+            build(
+              model, properties, required, other_def_properties
+            )
+          end
+        end
+
+        def parse_properties(properties)
+          other_properties = {}
+
+          discriminator_key, discriminator_value =
+            properties.find do |_key, value|
+              value[:documentation].try(:[], :is_discriminator)
+            end
+
+          if discriminator_key
+            discriminator_value.delete(:documentation)
+            properties[discriminator_key] = discriminator_value
+
+            other_properties[:discriminator] = discriminator_key
+          end
+
+          [properties, other_properties]
+        end
+
+        def parse_refs_and_models(refs_or_models, model)
+          refs_or_models.map do |ref_or_models|
+            if ref_or_models.is_a?(Hash) && ref_or_models.keys.first == '$ref'
+              ref_or_models
+            else
+              properties, required = ref_or_models
+              GrapeSwagger::DocMethods::BuildModelDefinition.build(model, properties, required)
+            end
+          end
+        end
+
         private
 
         def required_attributes(model)

lib/grape-swagger/doc_methods/parse_params.rb

@@ -77,6 +77,19 @@ def document_array_param(value_type, definitions)
 
           param_type ||= value_type[:param_type]
 
+          array_items = parse_array_item(
+            definitions,
+            type,
+            value_type
+          )
+
+          @parsed_param[:in] = param_type || 'formData'
+          @parsed_param[:items] = array_items
+          @parsed_param[:type] = 'array'
+          @parsed_param[:collectionFormat] = collection_format if DataType.collections.include?(collection_format)
+        end
+
+        def parse_array_item(definitions, type, value_type)
           array_items = {}
           if definitions[value_type[:data_type]]
             array_items['$ref'] = "#/definitions/#{@parsed_param[:type]}"
@@ -91,10 +104,7 @@ def document_array_param(value_type, definitions)
 
           array_items[:default] = value_type[:default] if value_type[:default].present?
 
-          @parsed_param[:in] = param_type || 'formData'
-          @parsed_param[:items] = array_items
-          @parsed_param[:type] = 'array'
-          @parsed_param[:collectionFormat] = collection_format if DataType.collections.include?(collection_format)
+          array_items
         end
 
         def document_additional_properties(settings)

lib/grape-swagger/endpoint.rb

@@ -196,10 +196,7 @@ def params_object(route, options, path)
     end
 
     def response_object(route, options)
-      codes = http_codes_from_route(route)
-      codes.map! { |x| x.is_a?(Array) ? { code: x[0], message: x[1], model: x[2], examples: x[3], headers: x[4] } : x }
-
-      codes.each_with_object({}) do |value, memo|
+      codes(route).each_with_object({}) do |value, memo|
         value[:message] ||= ''
         memo[value[:code]] = { description: value[:message] }
 
@@ -225,6 +222,12 @@ def response_object(route, options)
       end
     end
 
+    def codes(route)
+      http_codes_from_route(route).map do |x|
+        x.is_a?(Array) ? { code: x[0], message: x[1], model: x[2], examples: x[3], headers: x[4] } : x
+      end
+    end
+
     def success_code?(code)
       status = code.is_a?(Array) ? code.first : code[:code]
       status.between?(200, 299)
@@ -340,12 +343,10 @@ def expose_params_from_model(model)
       parser = GrapeSwagger.model_parsers.find(model)
       raise GrapeSwagger::Errors::UnregisteredParser, "No parser registered for #{model_name}." unless parser
 
-      properties, required = parser.new(model, self).call
-      unless properties&.any?
-        raise GrapeSwagger::Errors::SwaggerSpec,
-              "Empty model #{model_name}, swagger 2.0 doesn't support empty definitions."
-      end
-      @definitions[model_name] = GrapeSwagger::DocMethods::BuildModelDefinition.build(model, properties, required)
+      parsed_response = parser.new(model, self).call
+
+      @definitions[model_name] =
+        GrapeSwagger::DocMethods::BuildModelDefinition.parse_params_from_model(parsed_response, model, model_name)
 
       model_name
     end

spec/swagger_v2/inheritance_and_discriminator_spec.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'Inheritance and Discriminator' do
+  before :all do
+    module InheritanceTest
+      module Entities
+        # example from https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#models-with-polymorphism-supports
+        class Pet < Grape::Entity
+          expose :type, documentation: {
+            type: 'string',
+            is_discriminator: true,
+            required: true
+          }
+          expose :name, documentation: {
+            type: 'string',
+            required: true
+          }
+        end
+
+        class Cat < Pet
+          expose :huntingSkill, documentation: {
+            type: 'string',
+            description: 'The measured skill for hunting',
+            default: 'lazy',
+            values: %w[
+              clueless
+              lazy
+              adventurous
+              aggressive
+            ]
+          }
+        end
+      end
+      class NameApi < Grape::API
+        add_swagger_documentation models: [Entities::Pet, Entities::Cat]
+      end
+    end
+  end
+
+  context 'Parent model' do
+    let(:app) { InheritanceTest::NameApi }
+
+    subject do
+      get '/swagger_doc'
+      JSON.parse(last_response.body)['definitions']
+    end
+
+    specify do
+      subject['InheritanceTest::Entities::Pet'].key?('discriminator')
+      subject['InheritanceTest::Entities::Pet']['discriminator'] = 'type'
+      subject['InheritanceTest::Entities::Cat'].key?('allOf')
+    end
+  end
+end