In the last few months I have been working, together with a colleague, on an API client for several well-known systems and cloud providers. When we started, I was a novice in the Go programming language, I had no experience in programming API clients, and I trusted the makers of the APIs enough to have great expectations at them.
Today, a few months later, several hours programming later and a bunch of lines of code later, I am a better novice Go programmer, I have some experience in interfacing with APIs, and my level of trust in the API makers is well beneath my feet.
This article will be a not-so-short summary of the reasons why we started this journey and all the unexpected bad surprises we got along the way. Unfortunately, I will be able to show only snippets of the code we have written because I didn’t get the authorisation to make it public. I will make the effort to ensure that the snippets are good enough to help you get a better understanding of the topics.
OK, enough preface. It’s time to tell the story.
This is not an article about how you can work with JSON in Go: you can easily learn that from the articles and web pages in the bibliography. Rather, this post is about the concepts that you must understand clearly before you set yourself for the task. Don’t sweat, it’s just two concepts two, and I’ve tried to explain them here.
In the last few weeks I have worked together with a colleague to write some automation with Golang and the Atlassian Crowd API. With several separate user databases (and, at the current state, no hope to unify them in a smart way) it would be very handy to take advantage of the APIs offered by, say, G Suite to fetch all the email addresses related to a user and use that information to automatically deactivate that user from all systems.
Coming from a Perl 5 background, I was hoping that decoding and encoding JSON in Go was as simple as it is in Perl. But it turns out that it wasn’t, and it’s obvious if you think about it: as Perl 5 is weakly typed, decoding any typed data into an “agnostic” data structure must be simple. Encoding a weakly typed data structure into a typed format may be a bit trickier, but as long as you don’t have too many fancy data (i.e., in this context: strings made of only digits or non-obvious boolean representations) this will also work well. But with strongly typed Go and struct field names having side effects depending on upper-/lowercase, that’s a different story.
As it often happens in cases like this, you will not find all the information you need in a single place. This is my attempt to collect it all and hand it to you, so that you won’t have to waste as much time as I did. You will still have to read through stuff though.
In my quest to learn the Go language I am currently in the process of doing the Go Code Clinic. It’s taking me quite some time because instead of going through the solutions proposed in the course I try to implement a solution by myself; only when I have no idea whatsoever about how to proceed I peep into the solution to get some insight, and then work independently on my solution again.
I have been using Perl for more than 20 years now, seen Perl 4 bow out and Perl 5 come in and develop in that fantastic language that has helped me uncountable times in my professional life. During those years I’ve also considered learning another language, but I have been unable to take a stand for a long time.
And there came Go and the hype around Go, just like years ago there was a lot of hype around Java. But while whatever written in Java I came across was a big, heavy and slow memory eater, most of the tools I came across that were written in Go were actually good stuff — OK, still a bit bloated in size, but they actually worked. The opportunity came, and I finally gave Go a shot.