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    express-openapi-validate
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    0.6.1 • Public • Published

    express-openapi-validate

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    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

    const fs = require("fs");
    const express = require("express");
    const { OpenApiValidator } = require("express-openapi-validate");
    const jsYaml = require("js-yaml");
    
    const app = express();
    app.use(express.json());
    
    const openApiDocument = jsYaml.safeLoad(
      fs.readFileSync("openapi.yaml", "utf-8"),
    );
    const validator = new OpenApiValidator(openApiDocument);
    
    app.post("/echo", validator.validate("post", "/echo"), (req, res, next) => {
      res.json({ output: req.body.input });
    });
    
    app.use((err, req, res, next) => {
      const statusCode = err.statusCode || 500;
      res.status(statusCode).json({
        error: {
          name: err.name,
          message: err.message,
          data: err.data,
        },
      });
    });
    
    const server = app.listen(3000, () => {
      console.log("Listening on", server.address());
    });

    Or using match():

    // Apply to all requests
    app.use(validator.match());
    
    // On each request validator.validate("post", "/echo") is called automatically,
    // if it has a matching specification in the OpenAPI schema
    app.post("/echo", (req, res, next) => {
      res.json({ output: req.body.input });
    });

    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

    Currently unsupported features

    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:

    // Using validate()
    app.post("/echo", validator.validate("post", "/echo"), (req, res, next) => {
      res.json({ output: req.body.input });
    });
    
    // Using match()
    app.use(validator.match());
    app.post("/echo", (req, res, next) => {
      res.json({ output: req.body.input });
    });

    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:

    import { OpenApiValidator } from "express-openapi-validate";
    import fs from "fs";
    import jsYaml from "js-yaml";
    import request from "supertest";
    import app from "./app";
    
    const openApiDocument = jsYaml.safeLoad(
      fs.readFileSync("openapi.yaml", "utf-8"),
    );
    const validator = new OpenApiValidator(openApiDocument);
    
    test("/echo responses", async () => {
      const validateResponse = validator.validateResponse("post", "/echo");
      let res = await request(app).post("/echo").send({});
      expect(validateResponse(res)).toBeUndefined();
    
      res = await request(app).post("/echo").send({ input: "Hello!" });
      expect(validateResponse(res)).toBeUndefined();
    });

    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.

    Install

    npm i express-openapi-validate

    DownloadsWeekly Downloads

    9,029

    Version

    0.6.1

    License

    Apache-2.0

    Unpacked Size

    163 kB

    Total Files

    55

    Last publish

    Collaborators

    • hilzu