Add support for discriminator

lib/openapi_parser/errors.rb

@@ -43,6 +43,29 @@ def message
     end
   end
 
+  class NotExistDiscriminatorMappingTarget < OpenAPIError
+    def initialize(key, reference)
+      super(reference)
+      @key = key
+    end
+
+    def message
+      "discriminator mapping key #{@key} does not exist in #{@reference}"
+    end
+  end
+
+  class NotExistDiscriminatorPropertyName < OpenAPIError
+    def initialize(key, value, reference)
+      super(reference)
+      @key   = key
+      @value = value
+    end
+
+    def message
+      "discriminator propertyName #{@key} does not exist in value #{@value} in #{@reference}"
+    end
+  end
+
   class NotOneOf < OpenAPIError
     def initialize(value, reference)
       super(reference)

lib/openapi_parser/schema_validators/any_of_validator.rb

@@ -3,6 +3,10 @@ class AnyOfValidator < Base
     # @param [Object] value
     # @param [OpenAPIParser::Schemas::Schema] schema
     def coerce_and_validate(value, schema)
+      if schema.discriminator
+        return validate_discriminator_schema(schema.discriminator, value)
+      end
+
       # in all schema return error (=true) not any of data
       schema.any_of.each do |s|
         coerced, err = validatable.validate_schema(value, s)

lib/openapi_parser/schema_validators/base.rb

@@ -17,5 +17,23 @@ def initialize(validatable, coerce_value)
     def coerce_and_validate(_value, _schema)
       raise 'need implement'
     end
+
+    def validate_discriminator_schema(discriminator, value)
+      unless value.key?(discriminator.property_name)
+        return [nil, OpenAPIParser::NotExistDiscriminatorPropertyName.new(discriminator.property_name, value, discriminator.object_reference)]
+      end
+      mapping_key = value[discriminator.property_name]
+
+      # TODO: it's allowed to have discriminator without mapping, then we need to lookup discriminator.property_name
+      # but the format is not the full path, just model name in the components
+      mapping_target = discriminator.mapping[mapping_key]
+      unless mapping_target
+        return [nil, OpenAPIParser::NotExistDiscriminatorMappingTarget.new(mapping_key, discriminator.object_reference)]
+      end
+
+      # TODO: this is likely O(n) for each validation, we need to find it once during parsing
+      resolved_schema = discriminator.root.find_object(mapping_target)
+      validatable.validate_schema(value, resolved_schema)
+    end
   end
 end

lib/openapi_parser/schema_validators/one_of_validator.rb

@@ -3,6 +3,10 @@ class OneOfValidator < Base
     # @param [Object] value
     # @param [OpenAPIParser::Schemas::Schema] schema
     def coerce_and_validate(value, schema)
+      if schema.discriminator
+        return validate_discriminator_schema(schema.discriminator, value)
+      end
+
       # if multiple schemas are satisfied, it's not valid
       result = schema.one_of.one? do |s|
         _coerced, err = validatable.validate_schema(value, s)

lib/openapi_parser/schemas/schema.rb

@@ -1,5 +1,5 @@
 # TODO: support 'not' because I need check reference...
-# TODO: support 'discriminator', 'xml', 'externalDocs'
+# TODO: support 'xml', 'externalDocs'
 # TODO: support extended property
 
 module OpenAPIParser::Schemas
@@ -73,6 +73,7 @@ class Schema < Base
                         :example,
                         :deprecated
 
+
     # @!attribute [r] read_only
     #   @return [Boolean, nil]
     openapi_attr_value :read_only, schema_key: :readOnly
@@ -101,6 +102,18 @@ class Schema < Base
     #   @return [Hash{String => Schema}, nil]
     openapi_attr_hash_object :properties, Schema, reference: true
 
+    # @!attribute [r] discriminator
+    #   @return [Hash{String => Schema}, nil]
+    openapi_attr_objects :discriminator, Schema
+
+    # @!attribute [r] property_name
+    #   @return [String, nil]
+    openapi_attr_value :property_name, schema_key: :propertyName
+
+    # @!attribute [r] mapping
+    #   @return [Hash{String => String]
+    openapi_attr_value :mapping
+
     # @!attribute [r] additional_properties
     #   @return [Boolean, Schema, Reference, nil]
     openapi_attr_object :additional_properties, Schema, reference: true, allow_data_type: true, schema_key: :additionalProperties

spec/data/petstore-with-discriminator.yaml

@@ -0,0 +1,109 @@
+openapi: "3.0.0"
+info:
+  version: 1.0.0
+  title: Swagger Petstore
+  description: A sample API that uses a petstore as an example to demonstrate features in the OpenAPI 3.0 specification
+  termsOfService: http://swagger.io/terms/
+  contact:
+    name: Swagger API Team
+    email: [email protected]
+    url: http://swagger.io
+  license:
+    name: Apache 2.0
+    url: https://www.apache.org/licenses/LICENSE-2.0.html
+servers:
+  - url: http://petstore.swagger.io/api
+paths:
+  /save_the_pets:
+    post:
+      description: Creates a new pet in the store.  Duplicates are allowed
+      operationId: addPet
+      requestBody:
+        description: Pet to add to the store
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/PetBaskets'
+      responses:
+        '200':
+          description: pet response
+          content:
+            application/json:
+              schema:
+                type: object
+components:
+  schemas:
+    PetBaskets:
+      type: object
+      properties:
+        baskets:
+          type: array
+          items:
+            anyOf:
+              - "$ref": "#/components/schemas/SquirrelBasket"
+              - "$ref": "#/components/schemas/CatBasket"
+            discriminator:
+              propertyName: name
+              mapping:
+                cats: "#/components/schemas/CatBasket"
+                squirrels: "#/components/schemas/SquirrelBasket"
+    SquirrelBasket:
+      type: object
+      required:
+        - name
+      properties:
+        name:
+          type: string
+        content:
+          type: array
+          items:
+            "$ref": "#/components/schemas/Squirrel"
+    Squirrel:
+      type: object
+      required:
+        - name
+        - nut_stock
+      properties:
+        name:
+          type: string
+        born_at:
+          format: date-time
+          nullable: true
+          type: string
+        description:
+          nullable: true
+          type: string
+        nut_stock:
+          nullable: true
+          type: integer
+    CatBasket:
+      type: object
+      required:
+        - name
+      properties:
+        name:
+          type: string
+        content:
+          type: array
+          items:
+            "$ref": "#/components/schemas/Cat"
+    Cat:
+      type: object
+      required:
+        - name
+        - milk_stock
+      properties:
+        name:
+          type: string
+        born_at:
+          format: date-time
+          nullable: true
+          type: string
+        description:
+          nullable: true
+          type: string
+        milk_stock:
+          nullable: true
+          type: integer
+

spec/openapi_parser/schemas/discriminator_spec.rb

@@ -0,0 +1,100 @@
+require_relative '../../spec_helper'
+
+RSpec.describe OpenAPIParser::Schemas::RequestBody do
+  let(:root) { OpenAPIParser.parse(petstore_with_discriminator_schema, {}) }
+
+  describe 'discriminator' do
+    let(:content_type) { 'application/json' }
+    let(:http_method) { :post }
+    let(:request_path) { '/save_the_pets' }
+    let(:request_operation) { root.request_operation(http_method, request_path) }
+    let(:params) { {} }
+
+    it 'picks correct object based on mapping and succeeds' do
+      body = {
+        "baskets" => [
+          {
+            "name"    => "cats",
+            "content" => [
+              {
+                "name"        => "Mr. Cat",
+                "born_at"     => "2019-05-16T11 =>37 =>02.160Z",
+                "description" => "Cat gentleman",
+                "milk_stock"  => 10
+              }
+            ]
+          },
+        ]
+      }
+
+      request_operation.validate_request_body(content_type, body)
+    end
+
+    it 'picks correct object based on mapping and fails' do
+      body = {
+        "baskets" => [
+          {
+            "name"    => "cats",
+            "content" => [
+              {
+                "name"        => "Mr. Cat",
+                "born_at"     => "2019-05-16T11 =>37 =>02.160Z",
+                "description" => "Cat gentleman",
+                "nut_stock"   => 10 # passing squirrel attribute here, but discriminator still picks cats and fails
+              }
+            ]
+          },
+        ]
+      }
+      expect { request_operation.validate_request_body(content_type, body) }.to raise_error do |e|
+        expect(e.kind_of?(OpenAPIParser::NotExistRequiredKey)).to eq true
+        expect(e.message).to match("^required parameters milk_stock not exist.*?$")
+      end
+    end
+
+    it "throws error when discriminator mapping is not found" do
+      body = {
+        "baskets" => [
+          {
+            "name"    => "dogs",
+            "content" => [
+              {
+                "name"        => "Mr. Dog",
+                "born_at"     => "2019-05-16T11 =>37 =>02.160Z",
+                "description" => "Dog bruiser",
+                "nut_stock"   => 10 # passing squirrel attribute here, but discriminator still picks cats and fails
+              }
+            ]
+          },
+        ]
+      }
+
+      expect { request_operation.validate_request_body(content_type, body) }.to raise_error do |e|
+        expect(e.kind_of?(OpenAPIParser::NotExistDiscriminatorMappingTarget)).to eq true
+        expect(e.message).to match("^discriminator mapping key dogs does not exist.*?$")
+      end
+    end
+
+    it "throws error if discriminator propertyName is not present on object" do
+      body = {
+        "baskets" => [
+          {
+            "content" => [
+              {
+                "name"        => "Mr. Dog",
+                "born_at"     => "2019-05-16T11 =>37 =>02.160Z",
+                "description" => "Dog bruiser",
+                "milk_stock"   => 10
+              }
+            ]
+          },
+        ]
+      }
+
+      expect { request_operation.validate_request_body(content_type, body) }.to raise_error do |e|
+        expect(e.kind_of?(OpenAPIParser::NotExistDiscriminatorPropertyName)).to eq true
+        expect(e.message).to match("^discriminator propertyName name does not exist in value.*?$")
+      end
+    end
+  end
+end

spec/spec_helper.rb

@@ -32,6 +32,10 @@ def petstore_schema
   YAML.load_file('./spec/data/petstore-expanded.yaml')
 end
 
+def petstore_with_discriminator_schema
+  YAML.load_file('./spec/data/petstore-with-discriminator.yaml')
+end
+
 def build_validate_test_schema(new_properties)
   b = YAML.load_file('./spec/data/validate_test.yaml')
   obj = b['paths']['/validate_test']['post']['requestBody']['content']['application/json']['schema']['properties']