Jordan Nielson

First impressions of Postgraphile

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Over the last few months I've gotten to work on a project utilizing Postgraphile for the first time, and it was pretty fun! I was jumping into the project near the end, so I wasn't involved in setting up the library, but I did get a fair amount of usage time in and wanted to write down and consolidate some thoughts I had.

One of the first things I needed to do involving Postgraphile was changing the database schema, something that the other people working on the project had setup graphile/migrate to handle. It was super straightforward to use, which I appreciated, especially since Postgraphile didn't require a server restart after running migrations.

Some high level thoughts

After my first couple days I wrote down the following thoughts about Postgraphile. I'm sharing them pretty raw here, but I think they say a lot about the things that stuck out to me off the bat.

  • Security rules on the database level should exist anyway, so it makes sense to use those as your security model
  • Using comments on the columns to control what goes into the graphql is kind of mind-bending, but works super well
  • RLS (row-level security) in Postgres is nifty. Super nice for user-specific data.

Handling non-user inputs

One of the first tasks I was completing on the project was adding a new table for an upcoming section of the application. We wanted to keep track of created_at and updated_at timestamps (which should be set automatically and not by the user), something that I've done previously by using in the mutation handler that creates or updates the item. I'd frequently forget to include that in a spot and end up with actions that don't update the updated_at timestamp, causing inconsistencies! Inconsistencies are some of the worst bugs to track down in my opinion since they're usually super subtle and hard to replicate on demand.

Postgraphile's documentation recommends keeping created_at and updated_at correctly set for rows by utilizing a trigger. Following their recommendation was super straightforward, since their documentation had this exact example. This approach results in handling this at the database-level which lets you can manually test if it works by adding or updating a row directly in the database without needing to run it through the GraphQL layer and thereby avoid some complexities.

Sometimes you need to adjust your approach

At one point while working on the project we needed some file upload capabilities. I helped review the pull request adding this since it required changing how we had the server setup. Instead of utilizing Postgraphile middleware directly the PR changed the project to utilize apollo-server-express with Postgraphile as a plugin and schema generator.

We learned that sometimes there are things you need to do that a tool just can't do, like Postgraphile natively handling file uploads in the timeline we were working on... so you adjust and hack things together to make it work! Thankfully we were able to utilize a library postgraphile-apollo-server to make that transition easier and avoid needing to rewrite a bunch of code to get us on apollo-server.

Hidden functionality

After making the switch to apollo-server-express we learned that there was some functionality in the Postgraphile middleware that wasn't replicated as some things that didn't seem related broke after this change. The main thing we ran into was handling JSON objects is different between apollo-server-express and Postgraphile. Postgraphile automatically stringifies and parses JSON where needed, while apollo-server-express requires the developer to add that in where needed. Since we had started with the library that did it automatically, it was super painful to come across places we needed to do this after switching.

Things I liked in Postgraphile

Working with Postgraphile itself is actually super straightforward. As I mentioned in my high level thoughts earlier the reliance on the database for a lot of features makes a bunch of sense when your goal is to avoid re-working and duplicating features that already exist there. I really liked the experience of working so close to the database since if there were issues there was only 1, maybe 2, places to look for where that logic would be.

Another thing I really liked about the setup was the generated database schema file, since it made PR reviews super easy for database changes. For example, in order to adjust a function in Postgres you utilize CREATE OR REPLACE FUNCTION in your migration and would need to include the entire function in order for the migration to work properly. But, after the migrations were run the git diff of the generated schema only contained what actually changed making it super easy to validate in PR review.

There are always tradeoffs

One thing that I found while working with Postgraphile, and earlier last year while working with TypeORM, is that everything has tradeoffs. Something that one library chooses to make super easy to do will likely make something else way harder.

Things I want to look into with Postgraphile

  • Testing
  • Subscriptions
  • Debugging deeper problems

Something I've been wanting to focus more on is testing, especially in the node backend code that I write. I haven't seen much focus on testing in the overall node GraphQL ecosystem, but Postgraphile does have a guide on testing with jest available that looks pretty solid.

GraphQL subscriptions weren't needed for this project, but they're talked about in the Postgraphile documentation. I'd want to read through that before committing to using Postgraphile in a project that needs subscriptions since I have no idea how they are to work with.

Most issues I've run into with Postgraphile so far I've been able to work out through the GraphQL playground or direct database queries how to fix. I'd be interested in looking at the deeper debugging story - what happens when it seems like Postgraphile isn't working correctly. I've had to dig in like that a few times with TypeORM this last year and it was super painful since TypeORM has decent "info" logging, but very little "debugging" logs.

Would I start a new project with Postgraphile?

After spending a few months working on a project utilizing Postgraphile I think it's a solid pick for a project where you already have a postgres database and want to put a GraphQL server on top of it. The next project I'm working on is using Blitz.js which utilizes Prisma 2 for the default database client, and that seems like the option I would usually reach for. It should be fun!

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