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Use Accept Headers to GET XML Content as a preference

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How to complete the challenge GET /todos XML (200) to successfully GET all the todos in XML format as first preference.

GET /todos XML Preference (200)

It is possible to ask for multiple types in the Accept header, expressing a preference for the returned format. If none of the types are available then expect a 406 response.

Issue a GET request on the /todos end point with an Accept header of application/xml followed by application/json to receive results in XML format if supported, or JSON if not.

  • GET request will receive a response with all the todo items
    • e.g. GET /todos to get all the todo items
  • 200 is a success code, in this case it means the end point exists and the todo items were returned
  • Accept means that an Accept header was added to specify that the todos should be returned in XML format as first preference, followed by JSON as second preference
  • add the X-CHALLENGER header to track progress

Basic Instructions

  • Issue a GET request to end point "/todos"
    • if running locally that endpoint would be
      • https://apichallenges.com/todos
  • The request should have an Accept header specifying XML format by using a value of application/xml,application/json
  • The request should have an X-CHALLENGER header to track challenge completion
  • The response status code should be 200 when all the details are valid.
  • Check the body of the message has JSON format data, which is the default from the server
  • Check the content-type header in the response has application/json

The chained Accept header application/xml,application/json asks for XML as first preference, but if not supported then supply JSON. Because no q values are supplied, both media types behave as if they had q=1.0, so order is used to choose between equally preferred supported formats.

Try it now

GET /todos with XML preferred over JSON

Example Request

> GET /todos HTTP/1.1
> Host: apichallenges.com
> User-Agent: rest-client
> X-CHALLENGER: x-challenger-guid
> Accept: application/xml,application/json

Example Response

< HTTP/1.1 200 OK
< Connection: close
< Date: Sat, 29 May 2021 10:05:24 GMT
< Content-Type: application/xml
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Headers: *
< X-Challenger: x-challenger-guid
< Server: Jetty(9.4.z-SNAPSHOT)
< Via: 1.1 vegur

Example Response body:

<todos>
    <todo>
        <doneStatus>false</doneStatus>
        <description/>
        <id>267</id>
        <title>train staff</title>
    </todo>
    <todo>
        <doneStatus>false</doneStatus>
        <description/>
        <id>268</id>
        <title>schedule meeting</title>
    </todo>
</todos>

Overview Video

Watch on YouTube: "Solution to Get all Todos in XML as preferred format"

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Lessons Learned

  • Accept: application/xml,application/json expresses a preference order without q values.
  • Negotiation should return application/xml when XML is supported, not simply the API default.
  • Preference lists are useful for clients that can process a fallback format.
  • A supported lower-priority format still matters when a higher-priority format is unavailable.

Suggested Experiments

  • Reverse the header to Accept: application/json,application/xml and observe which Content-Type wins.
  • Add q values such as application/xml;q=0.5, application/json;q=1 and compare with the comma-order request.
  • Try Accept: application/problem+xml, application/xml;q=0.5 and confirm that the supported XML fallback can still be used.
Experiment with this endpoint

 

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