express-openapi-validate
Express middleware to validate requests based on an OpenAPI 3.0
document. OpenAPI specification was called the Swagger specification
before version 3.
Usage
Install this package with npm or yarn:
npm install --save express-openapi-validate
# or
yarn add express-openapi-validate
Then use the validator like this:
index.js
Or using match()
:
openapi.yaml
openapi: 3.0.1
info:
title: Example API with a single echo endpoint
version: 1.0.0
components:
schemas:
Error:
type: object
properties:
error:
type: object
properties:
name:
type: string
message:
type: string
data:
type: array
items:
type: object
required:
- name
- message
required:
- error
responses:
error:
description: Default error response with error object
content:
application/json:
schema:
$ref: "#/components/schemas/Error"
paths:
/echo:
post:
description: Echo input back
requestBody:
content:
application/json:
schema:
type: object
properties:
input:
type: string
required:
- input
responses:
"200":
description: Echoed input
content:
application/json:
schema:
type: object
properties:
output:
type: string
default:
$ref: "#/components/responses/error"
Supported features
- Validating request bodies with a schema (See Request Body
Object and Schema
Object)- All schema properties in a Schema Object that are directly supported by
JSON Schema and Ajv are used in validation - Schemas are validated according to JSON Schema Specification Wright Draft
00 (draft-04/05) as specified in OpenAPI
specification nullable
field for handling properties that can be null is supported (See
OpenAPI fixed fields)- Validation according to
format
including additional data type formats
(like int32 and bytes) defined by OpenAPI (See OpenAPI data
types and Ajv formats)
- All schema properties in a Schema Object that are directly supported by
- Validating parameters: query, header, path and cookies (including signed
cookies) (See Parameter Object)- The same
schema
features that are supported for request bodies are also
supported for parameters required
field for marking parameters that must be given is supported
- The same
- Validating response bodies and headers in tests (See Responses
Object and Header Object) - References to Components Object (See Reference
Object) - Typescript definitions are included in the package
- Discriminator keyword
Currently unsupported features
- Validating request bodies with media type other than
application/json
(See
content
under Request Body Object) - Some OpenAPI Schema Object specific fields are
unsupported:deprecated
xml
- External references (references to other files and network resources) (See
Reference Object) - Parameter Objects (including Header
Objects) that define shape usingcontent
andstyle
(onlyschema
is supported) - Links and callbacks (See Callback Object and Link
Object) - Encodings (See Encoding Object)
Public API
class OpenApiValidator
const { OpenApiValidator } = require("express-openapi-validate");
The main class of this package. Creates JSON schema validators
for the given operations defined in the OpenAPI document. In the background
Ajv is used to validate the request.
constructor(openApiDocument: OpenApiDocument, options: ValidatorConfig = {}))
Creates a new validator for the given OpenAPI document.
options
parameter is optional. It has the following optional fields:
{
ajvOptions: Ajv.Options;
}
You can find the list of options accepted by Ajv from its
documentation. The formats
object passed to Ajv will be merged
with additional OpenAPI formats supported by this library.
validate(method: Operation, path: string): RequestHandler
Returns an express middleware function for the given operation. The operation
matching the given method and path has to be defined in the OpenAPI document or
this method throws.
The middleware validates the incoming request according to the parameters
and
requestBody
fields defined in the Operation
Object. If the validation fails the next
express
function is called with an
ValidationError
.
See the Parameter Object and Request Body
Object sections of the OpenAPI specification for
details how to define schemas for operations.
method
must be one of the valid operations of an OpenAPI Path Item
Object:
"get" | "put" | "post" | "delete" | "options" | "head" | "patch" | "trace"
.
RequestHandler
is an express middleware function with the signature
(req: Request, res: Response, next: NextFunction): any;
.
match(options: MatchOptions = { allowNoMatch: false }): RequestHandler
Returns an express middleware function which calls validate()
based on the
request method and path. Using this function removes the need to specify
validate()
middleware for each express endpoint individually.
match()
throws an error if matching route specification is not found. This
ensures all requests are validated.
Use match({ allowNoMatch: true})
if you want to skip validation for routes
that are not mentioned in the OpenAPI schema. Use with caution: It allows
requests to be handled without any validation.
The following examples achieve the same result:
validateResponse(method: Operation, path: string): (res: any) => void
Creates a function for the given operation that can be used to validate
responses. Response validation is meant to be used in tests and not in
production code. See below for example usage.
For documentation of the method
and path
parameters see
validate
.
res
is expected to have the shape
{ statusCode: number, body: {}, headers: {}}
. The statusCode
field can also
be called status
and the body
field can be called data
. This means that
response objects from most request libraries should work out of the box.
If validation fails the validation function throws a
ValidationError
. Otherwise it returns
undefined
.
Example usage when using Jest and SuperTest:
class ValidationError extends Error
const { ValidationError } = require("express-openapi-validate");
This error is thrown by OpenApiValidator#validate
when the request validation
fails. It contains useful information about why the validation failed in
human-readable format in the .message
field and in machine-readable format in
the .data
array.
You can catch this error in your express error handler and handle it specially.
You probably want to log the validation error and pass the errors to the client.
message: string
Human-readable error message about why the validation failed.
statusCode: number = 400
This field is always set to 400
. You can check this field in your express
error handler to decide what status code to send to the client when errors
happen.
data: ErrorObject[]
Machine-readable array of validation errors. Ajv Error
Objects documentation contains a list of the fields in
ErrorObject
.