# AWS CloudFormation template of a sample API with basic request validation
<a name="api-gateway-request-validation-sample-cloudformation"></a>

 The following CloudFormation example template definition defines a sample API with request validation enabled. The API is a subset of the [PetStore API](http://petstore-demo-endpoint.execute-api.com/petstore/pets). It exposes a `POST` method to add a pet to the `pets` collection and a `GET` method to query pets by a specified type. 

 There are two request validators declared:

**`GETValidator`**  
This validator is enabled on the `GET` method. It allows API Gateway to verify that the required query parameter (`q1`) is included and not blank in the incoming request. 

**`POSTValidator`**  
This validator is enabled on the `POST` method. It allows API Gateway to verify that payload request format adheres to the specified `RequestBodyModel` when the content type is `application/json` if no matching content type is found, request validation is not performed. To use the same model regardless of the content type, specify `$default`. `RequestBodyModel` contains an additional model, `RequestBodyModelId`, to define the pet ID.

```
AWSTemplateFormatVersion: 2010-09-09
Parameters:
  StageName:
    Type: String
    Default: v1
    Description: Name of API stage.
Resources:
  Api:
    Type: 'AWS::ApiGateway::RestApi'
    Properties:
      Name: ReqValidatorsSample
  RequestBodyModelId:
    Type: 'AWS::ApiGateway::Model'
    Properties:
      RestApiId: !Ref Api
      ContentType: application/json
      Description: Request body model for Pet ID.
      Schema:
        $schema: 'http://json-schema.org/draft-04/schema#'
        title: RequestBodyModelId
        properties:
            id:
              type: integer
  RequestBodyModel: 
    Type: 'AWS::ApiGateway::Model'
    Properties:
      RestApiId: !Ref Api
      ContentType: application/json
      Description: Request body model for Pet type, name, price, and ID.
      Schema:
        $schema: 'http://json-schema.org/draft-04/schema#'
        title: RequestBodyModel
        required:
          - price
          - name
          - type
        type: object
        properties:
            id:
              "$ref": !Sub 
                - 'https://apigateway.amazonaws.com/restapis/${Api}/models/${RequestBodyModelId}'
                - Api: !Ref Api
                  RequestBodyModelId: !Ref RequestBodyModelId
            price: 
              type: number
              minimum: 25
              maximum: 500
            name:
              type: string
            type:
              type: string
              enum:
                - "dog"
                - "cat"
                - "fish"
  GETValidator:
    Type: AWS::ApiGateway::RequestValidator
    Properties:
      Name: params-only
      RestApiId: !Ref Api
      ValidateRequestBody: False
      ValidateRequestParameters: True 
  POSTValidator:
    Type: AWS::ApiGateway::RequestValidator
    Properties:
      Name: body-only
      RestApiId: !Ref Api
      ValidateRequestBody: True
      ValidateRequestParameters: False
  ValidationResource:
    Type: 'AWS::ApiGateway::Resource'
    Properties:
      RestApiId: !Ref Api
      ParentId: !GetAtt Api.RootResourceId
      PathPart: 'validation'
  ValidationMethodGet:
    Type: 'AWS::ApiGateway::Method'
    Properties:
      RestApiId: !Ref Api
      ResourceId: !Ref ValidationResource
      HttpMethod: GET
      AuthorizationType: NONE
      RequestValidatorId: !Ref GETValidator
      RequestParameters:
        method.request.querystring.q1: true
      Integration:
        Type: HTTP_PROXY
        IntegrationHttpMethod: GET
        Uri: http://petstore-demo-endpoint.execute-api.com/petstore/pets/
  ValidationMethodPost:
    Type: 'AWS::ApiGateway::Method'
    Properties:
      RestApiId: !Ref Api
      ResourceId: !Ref ValidationResource
      HttpMethod: POST
      AuthorizationType: NONE
      RequestValidatorId: !Ref POSTValidator
      RequestModels:
        application/json : !Ref RequestBodyModel 
      Integration:
        Type: HTTP_PROXY
        IntegrationHttpMethod: POST
        Uri: http://petstore-demo-endpoint.execute-api.com/petstore/pets/
  ApiDeployment:
    Type: 'AWS::ApiGateway::Deployment'
    DependsOn:
      - ValidationMethodGet
      - RequestBodyModel 
    Properties:
      RestApiId: !Ref Api
      StageName: !Sub '${StageName}'
Outputs:
  ApiRootUrl:
    Description: Root Url of the API
    Value: !Sub 'https://${Api}.execute-api.${AWS::Region}.amazonaws.com/${StageName}'
```