We have some queries that are a bit slow because it's easy to ask a lot in GraphQL, but the alternative would be to do hundreds of HTTP queries if we were using REST for example.
The tooling is particularly good nowadays. My company use it in NodeJS with Apollo and TypeScript and it's very good and stable. I also did some side projects in Rust and it was very pleasing to use too.
One common problem is the caching, you can't easily cache using normal HTTP CDN software for example, but since our API requires to be authenticated for anything, it's not a problem for us. We just do cache in other places.
We have some simpler API not using GraphQL but I would strongly recommend GraphQL as soon as your API is not tiny.
REST Api design is probably one of the least value-add activities a company can involve itself in. Any standard that defines a standard way of performing set operations, GraphQL or even the ancient ODATA, is superior.
But one thing will always remain and you have to remember is that graphql is slow by design. If performance is critical to you, don't use it
This turned out in retrospect to be a good call. The primary consumers of the API were a set of Android and iOS apps, and integrating GraphQL into mobile apps is a pleasant experience. You can generate your data models from the graph schema. Tools like GraphiQL allow developers to explore and play with your API, substantially reducing the amount of documentation needed. The mobile team much preferred working with GraphQL over REST.
On the backend, GraphQL has a bit of a learning curve. The resolver pattern is powerful once you understand how to use it properly, but also easy to misuse. The most common source of problems is developers not understanding Graph's batch resolution mechanism. Developers accustomed to building REST APIs rely on preloading data, which is the wrong approach when dealing with GraphQL.
As a simple example, maybe you initially build a Graph query where you load comments like this:
query Comments {
user {
posts {
comments {
message
}
}
}
}
But later on, you decide you want to allow a user to load their comment history directly: query Comments {
user {
comments {
message
}
}
}
In the first example, an equivalent REST API might load comments via something like posts.preload(:comments), and when the second query is built you'd use user.preload(:comments). But the way to solve this problem in Graph is batch resolution - get a list of comment IDs you want to load, then call Comment.where(id: comments_ids). Your comment loading is now context agnostic.Another related problem is that it is easy to create N+1 queries. This also stems from a misunderstanding of batch resolution - reusing the above example it would be the equivalent of calling Comment.find(comment_id) for each ID instead of Comment.where(id: comments_ids). My first few months working with Graph were often spent fixing N+1 queries. As much as I try to explain this problem to new developers, it's one of those things that doesn't click for them until they cause the problem and end up having to fix it.
Once you understand GraphQL it's a nice technology to work with. In the early stages it can be fairly easy to shoot yourself in the foot, you just need to build up enough knowledge to avoid the common pitfalls. In general, GraphQL APIs are harder to build than REST APIs (mostly because REST is the default for most frameworks). If I had to start a new project today, my decision on whether to use GraphQL would be be determined by questions such as:
1. How much control do I have over the clients
2. Are the primary consumers native mobile applications
3. Is flexibility important
4. Will API documentation be required