Moving build_runner to the Context Menu in VS Code

Shorten build_runner run time & regenerate only needed files in just two clicks.

Quite a lot of Dart & Flutter projects rely on code generation, delegating the burden of writing boilerplate code to a script. Although the more the project grows, the longer & less attractive code generation becomes. I heard wild stories about code generation taking more than half an hour to rebuild everything (I’m sure there’s more). And simply using the watch command wasn’t helping: a small change was still triggering a few minutes of rebuilding.

Luckily, my situation is better. On my current project, it takes 4 minutes for my laptop to generate the code. Not that long, I agree. But we lose the beauty of hot reload if we need to wait until code generation completes.

So how do we keep it short & convenient?

Photo by Andrik Langfield on Unsplash

Configuring the generators

It is possible to tell specific code generation builders to work with needed files. For example, we can tell Freezed to generate only *_model.dart files. For this, we need to configure in the build.yaml file:

targets:
  $default:
    builders:
      freezed:freezed:
        generate_for:
          include:
            - lib/**model.dart
            # Or we can limit it even more:
            - lib/data/**_dto.dart

# Etc etc etc

With this, we make sure that Freezed doesn’t work, say, with *_screen.dart or *_widget.dart classes. Similarly, we can exclude files.

While it’s great, it can still be quite time consuming to regenerate all the model classes in your project.

Utilizing build-filter

build_runner has a parameter build-filter that allows to specify which files to work with. It can be used for a single or multiple relative paths to files:

dart run build_runner build  --release --build-filter=lib/data/ad
min.freezed.dart --build-filter=lib/data/admin.g.dart

With this command, only the specified files will be regenerated.

Note that this must be ran on generated files, not on source files. In the given example, admin.dart contains all the required freezed & json_serializable configuration whereas .freezed.dart and .g.dart are generated files.

But files are not always stored under lib/data. Your project might have a complex & deep-nested folder structure making file paths long. Gathering these paths of required files, using them as build-filters, running a terminal command… Boring. Not mentioning we have to do it again for a new set of files.

I couldn’t resist putting this joke here. Pardon me!

Solution

… is quite simple. Somehow optimize code generation by collecting relative paths of the required files & passing it to build_runner automatically.

For example, we can move it to the context menu of the VS Code’s file explorer, so you can right click files and regenerate them. Like this:

Here’s how it’s going to look like.

Bringing it to your table

All you need to do is to install the build_runner Tools extension. After that, you will see 4 new commands in the context menu when you right click .dart files or folders:

• Build / Watch this: runs build_runner on the selected files. It simply maps relative paths of the selected files to build-filter params and launches build_runner. Must be ran on generated files like .g.dart.
• Build / Watch parts: unlike the “this” command, it reads the selected files / folders and collects all the part directives. Must be run on files like admin.dart from the example above. The extension will automatically launch build_runner on the admin.g.dart and admin.freezed.dart files since it’s referenced in the source file itself.

More examples and possible answers to your questions are in the extension’s description itself.

That’s it folks!

I couldn’t come up with a conclusion, so I’ll just put a philosophical statement here:

Time is one of the most valuable things in this world. There are better ways to spend it rather than waiting for code generation to complete.

Reach out to me in Telegram or join my technical blog there. I will be happy to have you.

Peace and light to your house.