Note This repository has moved to https://github.com/kogosoftwarellc/open-api/tree/master/packages/express-openapi-response-validation

express-openapi-response-validation

Express middleware for openapi response validation.

Provides a .validateResponse method to express response objects. If the method returns a value, it will be a validation error with status: 500, a message, and an optional array of errors.

Highlights

• Performant.
• Extensively tested.
• Small footprint.
• Leverages jsonschema.
• Currently supports openapi 2.0 (a.k.a. swagger 2.0) responses objects.
• Supports $ref in response schemas i.e. #/definitions/SomeType.

Example

See ./test/data-driven/*.js for more examples.

var app = require('express')();
var validateResponseMiddleware = require('express-openapi-response-validation')({
  responses: {
    200: {
      description: 'We found what you were looking for.',
      schema: {
        $ref: '#/definitions/ResourceResponse'
      }
    },
    default: {
      description: 'Something happened...',
      schema: {
        $ref: '#/definitions/SomeErrorResponse'
      }
    }
  },
  definitions: {
    ResourceResponse: {
      type: 'object',
      properties: {
        id: {
          type: 'integer'
        },
        name: {
          type: 'string'
        }
      },
      required: ['id', 'name']
    },
    SomeErrorResponse: {
      type: 'object',
      properties: {
        errorCode: {
          type: 'string'
        },
        message: {
          type: 'string'
        }
      }
    }
  }
});

app.get('/something', validateResponseMiddleware, function(req, res, next) {
  var someResource = {};
  var validationError = res.validateResponse(200, someResource);

  /*
    Validation errors look like this (except for objects in the errors array which
    may be overridden with errorTransformer):
    {
      status: 500,
      message: 'The response was not valid.',
      errors: [
        {
          path: 'foo',
          errorCode: 'type.openapi.responseValidation',
          message: 'foo is not of a type(s) string'
        }
      ]
    }
  */

  if (validationError) {
    return next(validationError);
  } else {
    res.status(200, someResource);
  }
});

API

module(args)

Returns an express middleware function.

args

Type	Required	Default Value	Description
Object	Y	N/A	Arguments to configure the middleware.

args.responses

Type	Required	Default Value	Description
Object	Y	N/A	A key value pair of response definitions. At least one response definition is to be provided.

Keys may be any HTTP status code or default (for all HTTP status codes). See http://swagger.io/specification/#responsesObject.

args.definitions

Type	Required	Default Value	Description
Object	N	N/A	A key value pair of type definitions

This object is used to support $ref in your responses

args.errorTransformer

Type	Required	Default Value	Description
Function	N	toOpenapiValidationError (see the source)	A function that receives an error and returns a mapped version of the error.

This function is passed 2 arguments.

  errorTransformer: function(openapiError, jsonschemaError) {
    return {
      message: openapiError.message
    };
  }

See the error format in jsonschema for jsonschemaError. openapiErrors have the following properties:

• errorCode - A jsonschema error suffixed with .openapi.validation. failed.
• message - A detailed message as to why validation failed.
• path - The property of the response body that failed validation.

args.customFormats

Type	Required	Default Value	Description
Object	N	null	An object of custom formats.

Each key is the name of the format to be used with the format keyword. Each value is a function that accepts an input and returns a boolean value.

See Custom Formats in jsonschema.

LICENSE

The MIT License (MIT)

Copyright (c) 2016 Kogo Software LLC

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.