Postman Tips and Tricks 👨‍🚀

Over the past year, I've been working a lot with Postman - an API platform for building and using APIs.

Postman has really improved over the past few years. I've found it hard to keep up with all of the changes made to Postman! It's only recently that Postman can capture response using it's own proxy.

I thought that in this post I'd share several tips and tricks that I've picked up over the past year. So let's dive in.

Postman Interceptor with Swagger UI

The Interceptor is a fantastic way of capturing HTTP requests from within your browser. The best way I've used the Interceptor extension is working with Swagger UI. If you submit a request via Swagger with the Interceptor running, you'll capture the request to the API. Even though the request could return a response you weren't expecting, it still captures the headers and the request you sent. This could save some time with writing tests for the same endpoint.

Environments can share the same name for variables.

Say you have an application that can is deployed onto three different environments; test, dev, preproduction. You have a postman collection that can run on each environment, and the only difference is the URL used for each environment (i.e, testapp.com, devapp.com). How can we easily manage this without duplicating the collection (one for each environment)? Simply create environments in Postman where each share the same name for a variable (but have different values).

Example:

Environment 1 Name: Dev App Variable: environment Value: devapp.com

Environment 2 Name: Test App Variable: environment Value: testapp.com

These two environments have a variable that although has the same name, the value is different. So if we were to use these variables in a request on Postman, it would look like this:

www.{{environment}}/hello

The application has the endpoint called hello, but by changing the environment in postman - the collection can be used across multiple environments. This avoids duplicating the collection!

Working with XML

I honestly hate XML - it's the worst thing to work with in Postman. Thankfully, there is a great method called xml2Json which takes an XML response and converts into a JSON!

Like so:

var jsonObject = xml2Json(responseBody);
console.log(jsonObject);

And then you can access different properties of the response:

console.log(jsonObject['soap:Envelope']['soap:Body']['Property'])

Now you can work with XML using your existing knowledge of working with JSON!

Don't forget to clear your variables!

One thing I found when working with Postman is that sometimes, you can refer to variables which can have a value that you weren't expecting. I had this happen when I had several folders where the initial setup was the same but had slightly different variations to them.

To avoid any cross over from variables in previous requests, I started to clear out the variables at the end of a series of requests.

This can be done like so:

pm.globals.clear();
pm.environment.clear();
pm.collectionVariables.clear();

Just remember that this is a destructive method. Once it runs, it removes the variables from the current scope! So only use it if you really need it!

Remember you can export your requests as code snippets in different languages!

One handy feature of Postman is to export your request into another language! From C# to Ruby, Postman can export your request so you can make the same request in a different language. It's a cool trick if you're working on an application that makes a request to the endpoint you're using in Postman.

You can disable automatic redirects (HTTP 3xx)

An issue I found a few months back was where a request I had was automatically redirecting. I was trying to get a particular response from an API but since one of the responses was a 3xx it redirected it. Myself and a colleague did some research and found that there is an option in the settings for a request.

Under settings for a request (not the settings for Postman), you can disable the automatic redirects if the response is 3xx.

No more redirects for that request!

Don't forget about Newman!

Have a CI and want to use Postman? Not a problem! Use newman!

This handy CLI version of Postman is installed via NPM and runs your collection (once exported as a JSON)!

The documentation shows a range of useful options such as environments and global files.

It's great that this tool exists, especially if you want to automate a lot of your testing using your Postman collection.

That about wraps up this post! I'll do another Postman tips and tricks post in the future (or even just a post about Postman). I do encourage you to read the Postman blog and read the release notes for new versions as they provide a great insight in what's changed and what's going on at Postman in general.

Thanks for reading! 👏