@middy/http-response-serializer
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    4.0.0 • Public • Published

    Middy http-response-serializer middleware

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    HTTP response serializer middleware for the middy framework, the stylish Node.js middleware engine for AWS Lambda

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    You can read the documentation at: https://middy.js.org/docs/middlewares/http-response-serializer

    The Http Serializer middleware lets you define serialization mechanisms based on the current content negotiation.

    Install

    To install this middleware you can use NPM:

    npm install --save @middy/http-response-serializer

    Configuration

    The middleware is configured by defining some serializers.

    {
      serializers: [
        {
          regex: /^application\/xml$/,
          serializer: ({ body }) => `<message>${body}</message>`,
        },
        {
          regex: /^application\/json$/,
          serializer: ({ body }) => JSON.stringify(body)
        },
        {
          regex: /^text\/plain$/,
          serializer: ({ body }) => body
        }
      ],
      defaultContentType: 'application/json'
    }
    

    The defaultContentType (optional) option is used if the request and handler don't specify what type is wanted.

    Serializer Functions

    When a matching serializer is found, the Content-Type header is set and the serializer function is run.

    The function is passed the entire response object, and should return either a string or an object.

    If a string is returned, the body attribute of the response is updated.

    If an object with a body attribute is returned, the entire response object is replaced. This is useful if you want to manipulate headers or add additional attributes in the Lambda response.

    Content Type Negotiation

    The header is not the only way the middleware decides which serializer to execute.

    The content type is determined in the following order:

    • event.requiredContentType -- allows the handler to override everything else
    • The Accept header via accept
    • event.preferredContentType -- allows the handler to override the default, but lets the request ask first
    • defaultContentType middleware option

    All options allow for multiple types to be specified in your order of preference, and the first matching serializer will be executed.

    Sample usage

    import middy from '@middy/core'
    import httpResponseSerializer from '@middy/http-response-serializer'
    
    const handler = middy((event, context) => {
      const body = 'Hello World'
    
      return {
        statusCode: 200,
        body
      }
    })
    
    handler
      .use(httpResponseSerializer({
        serializers: [
          {
            regex: /^application\/xml$/,
            serializer: ({ body }) => `<message>${body}</message>`,
          },
          {
            regex: /^application\/json$/,
            serializer: ({ body }) => JSON.stringify(body)
          },
          {
            regex: /^text\/plain$/,
            serializer: ({ body }) => body
          }
        ],
        defaultContentType: 'application/json'
      }))
    
    const event = {
      headers: {
        'Accept': 'application/xml;q=0.9, text/x-dvi; q=0.8, text/x-c'
      }
    }
    
    handler(event, {}, (_, response) => {
      t.is(response.body,'<message>Hello World</message>')
    })

    Middy documentation and examples

    For more documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.

    Contributing

    Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.

    License

    Licensed under MIT License. Copyright (c) 2017-2022 Luciano Mammino, will Farrell, and the Middy team.

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    Install

    npm i @middy/http-response-serializer

    Homepage

    middy.js.org

    DownloadsWeekly Downloads

    15,704

    Version

    4.0.0

    License

    MIT

    Unpacked Size

    13.8 kB

    Total Files

    6

    Last publish

    Collaborators

    • lmammino
    • middyjs
    • willfarrell