Allow to manually add NPM dependencies (peerDependencies, devDependencies and dependencies)

[jjoslet]

This is currently possible to add import declarations but there is no way to add NPM dependencies in the package.json file from the configuration.

In addition, the package.json model does not handle peerDependencies.

Here is an example useage:

1. Map java.time.LocalDate to JS Joda LocalDate
2. Import JS Joda package using importDeclarations
3. Add js joda package to peerDependencies, devDependencies and/or dependencies.

[vojtechhabarta]

I think we should add npmDependencies parameter to support use-case you mentioned.

But I would not add parameters for other types of dependencies unless there is a real need for it. In more complex situations it is always possible to enrich generated package.json file in next build step for example using npm install command with respective parameter.

[jjoslet]

Here's my company use cases if it can help you undesrtand why we want to use this feature.

We write µService with Spring Boot that provide REST API consumed by both Java and Angular frontend.

Since these pieces of software are mainly written by the same team, we manage to share the API model between the backend and the frontend.
So we write the API model in Java (annotated with Jackson) and generate it to TypeScript using your Maven Plugin.
The Maven model project build a Java package and a NPM package, both published to our company repository.

We have many application that follows that pattern.

Therefore, in our Angular common framework, we create tool to deserialize JSON and verify it against the model. We use the reflect-metadata package to decorate the generated model.
I write a plugin to your generator to generate the meta-data. These meta-data has a dependency to our meta-data API. This API is then a dependency of our framework and our models.

In that situation, this dependency has to be a peerDependency to avoid issues when the model and the framework communicate using our meta-data library.

Since a peerDependency is not automatically installed by the Node tools during development, this dependency must also be a devDependency to ease the development.

In the NPM world, a dependency must be a peerDependency if this dependency is part of the API. If it's an internal dependency, it must be a "normal" dependency.

Source: https://nodejs.org/en/blog/npm/peer-dependencies/

Please note that one cannot use npm install tool to add peerDependency in the package.json (https://docs.npmjs.com/cli/v6/commands/npm-install and npm/npm#3994).

I see that there is also an optionalDependencies and a bundleDependencies in the package.json that can be useful for someone one day.

[vojtechhabarta]

Thanks for your use case and the link to a great explanation of peer dependencies. Just for curiosity: if you would put reflect-metadata into "normal" dependencies it should work most of the time because dependencies are installed flattened (top-level) in node_modules these days but it would break if two dependencies would declare different versions of reflect-metadata in their dependencies in which case it would not be installed top-level? Anyway I agree that peer dependency is the right solution.

[jjoslet]

You're right.

Suppose two packages depA and depB that both depend to reflect-metadata as a "normal" dependency and my-project uses these two dependencies.

If they both depend on the same version of reflect-metadata, there is no problem, it'll be installed at the root of my-project.

If they depend to different version of reflect-metadata, one reflect-metadata will be hosted at the root node_modules of my-project, the second will be hosted in the package specific node_modules. Something like that:

my-project
├── depA
├── reflect-metadata@1.0.0
└── depB
    └── reflect-metadata@2.0.0

This can then cause trouble with instanceof.

[vojtechhabarta]

Released in 2.30.840.