build VS json_serializable.dart

The official documentation is here. It's not very beginner friendly. Therefore, it might be easier to look at the examples.

In the first part of this series of posts, we discussed how Flutter and -Dart in general- makes use of builders to generate source code during the build process.

build: "Defines the basic pieces of how a build happens and how they interact."

build_runner

Having spent about 6 months each with SwiftUI and Flutter I vastly prefer working with Flutter. Swift is a far more ambitious language but really doesn't live up to it's own marketing. Many of the features are half down (generics and protocols are both full of holes). Dart on the other hand doesn't have half as many nice features but the one's that are there are rock solid. Reified generics in particular is far nicer to work with (Swift's compiler gets regularly gets lost on type resolution and then doesn't give you any way to give it hints). Dart also seems to be heading in the right direction. It's added null safety and the upcoming metaprogramming features should fill in many of the gaps that are currently filled by the very practical but clunky https://pub.dev/packages/build.

I am one of the authors of the build package (https://github.com/dart-lang/build) which does effectively expose a plugin system. We take the approach of creating a wrapper script that actually just generates the real program (adds imports to the plugins, registers them, etc) and then it just runs that program. There are several downsides to this approach though (primarily, slow startup).

If you really want to write it yourself, sure. This code is very easily automatically generated.

https://pub.dev/packages/json_serializable

Serializing and deserializing json is easy thanks to the json_serializable integration. Makes it impossible to make mistakes like you would normally when working with dynamic values and strings.

We will now create a new file called build.yaml in the failures directory and add the following code. This will change the behaviour of the json_serializable so that it generates JSON keys in snake_case.

Once the package has been created, we will install freezed for JSON serialization and value equality , as this library provides helpful tools for these tasks. We will use json_serializable for JSON serialization. To install freezed and freezed_annotation, open your terminal inside the models package and use the command:

However, we cannot do this kind of JSON de-serialization in Flutter. Without reflection, we need to consider other approaches for these same tasks. For instance, the package json_serializable uses source code generation for decorating classes with methods to serialize and de-serialize JSON strings.

We could work around having to introduce parsing logic by using a package such as json_serializable to parse data to and from JSON to save ourselves some time. However, you'd need to make sure the native platforms are returning the data in the exact format you are expecting, and vice versa. Otherwise the parsing will fail.

json_serializable - Provides Dart Build System builders for handling JSON.

The other ways involve using a package like json_serializable. They automatically generate boilerplate code to convert between your model classes and JSON. The issue is that Flutter doesn't support reflection (Dart does, but Flutter for mobile doesn't due to performance reasons) so any kind of library that generates code needs to do so statically. All packages involve annotating your classes and then running a builder script that generates the boilerplate code.