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Working with XML payloads

Molly Exten
  • Updated

If you're testing an API that uses XML payloads, such as SOAP APIs, you can validate responses and create variables using custom post-request scripts. Here’s a quick overview of the steps to accomplish this:

  1. Add a new API snippet to the post-request script
  2. Use the built-in xml2json library to convert the XML response body to a JSON object
  3. Use JSON path notation to iterate over object keys to find the target property
  4. Create a variable or an assertion using Postman pm. methods

This article uses the Fahrenheit to Celsius endpoint from W3Schools to demonstrate how to work with XML payloads in the API Test Editor:

Add variables

This example will assert that the value of tempF is correctly converted to the value of tempC. Add the following variables to the Variables panel:

  • tempF = 32
  • tempC = 0

Configure request details

Add a request with the following details:

In the Body tab of Request Details, add the following raw XML request body:

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
   <soap:Body>
    <FahrenheitToCelsius xmlns="https://www.w3schools.com/xml/">
      <Fahrenheit>{{@tempF}}</Fahrenheit>
    </FahrenheitToCelsius>   
   </soap:Body>
</soap:Envelope>

Send the request

When you send the POST request, the API returns an XML response body with the temperature of tempF in Celsius. In this example, the temperature is 0.

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <soap:Body>
    <FahrenheitToCelsiusResponse xmlns="https://www.w3schools.com/xml/">
      <FahrenheitToCelsiusResult>0</FahrenheitToCelsiusResult>
    </FahrenheitToCelsiusResponse>
  </soap:Body>
</soap:Envelope>

Validate the response

To assert that the value of <FahrenheitToCelsiusResult>0</FahrenheitToCelsiusResult> value equals the value of the tempC variable, add a new snippet to the Post-request tab in the Validation and variable assignment section.

The following script takes the following steps to validate the response:

  1. Convert the XML response body into a JSON object with the xml2Json library
  2. Use JSON path notation to get the value FahrenheitToCelsius
  3. Assert that the value of FahrenheitToCelsius equals the value of the variable tempC 
pm.test("Validate conversion Fahrenheit To Celsius produces the expected result", () => {

   //convert XML response body to a JSON object using xml2Json library
   const responseJson = xml2Json(pm.response.text());

   //Use JSON path syntax to get to the target property
   let result = responseJson["soap:Envelope"]["soap:Body"].FahrenheitToCelsiusResponse.FahrenheitToCelsiusResult;

   //Assert that result is the correct value
   pm.expect(result).to.eql(pm.variables.get("tempC"));
});

Create a new variable

Creating a variable based on an XML response body requires the same initial steps that it takes to validate data in an XML-based response body: converting the XML to JSON with xml2json library and finding the target property value of FahrehheitToCelsiusResult with JSON path notation.

Use the pm.environment.set() method to assign the result to a variable.

//convert XML response body to a JSON object using xml2Json library
const responseJson = xml2Json(pm.response.text());

//Use JSON path syntax to get to the target property value to be assigned to a variable
let result = responseJson["soap:Envelope"]["soap:Body"].FahrenheitToCelsiusResponse.FahrenheitToCelsiusResult;

//Assign the result value to a given variable name
pm.environment.set("myTemperature", result);

To see the updated myTemperature variable value when you send the request, add myTemperature to the Variables list on the left side of the API Test Editor.

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