A way to get value out of composed generator?

[thejohnfreeman]

I'd like to send my users to generator-license to let them choose a license, but I need to know that choice after it runs to put it in the project metadata file I generate. Is there an API for getting values out of subgenerators? Can there be?

[SBoudrias]

You could read it from the package.json file after the generator-license run.

There's no API to pass data outside a composed generator. The system isn't design to allow this kind of interactions.

[thejohnfreeman]

generator-license does not emit a package.json, nor do I want it to. I'm trying to scaffold a Python project. Thank you for the answer regardless!

[FrederickEngelhardt]

One way to do this would be to bind an update function to an object. Firing the function would then update the original generator.

In my use case, I want to combine a bunch of generators and update the file only once if possible. My root app generator will do this while my sub generators will only update the object that the root generator will eventually reference to create a file.

Example:

// Generator 1
module.exports = class extends Generator {
constructor(args, opts) {
    super(args, opts)

    this.packageJson = {
      name: 'test'
    }

    this._updatePackageJson = this._updatePackageJson.bind(this)
  }
 _updatePackageJson(newValues: Record<string, any>) {
    this.packageJson = merge(this.packageJson, newValues)
  }

  initializing() {
    this.composeWith('generator2', {
      configuration: this.configuration,
      updatePackageJson: this._updatePackageJson,
    })
  }
}

// generator 2
module.exports = class extends Generator {
constructor(args, opts) {
    super(args, opts)
    this.updatePackageJson = opts.updatePackageJson
  }

  updatePackageFunction(){
     this.updatePackageJson({ name: 'hello world' })
 }
}

[thejohnfreeman]

That requires both generators to be aware of each other. It doesn't work when composing with an arbitrary generator.

[mshima]

That requires both generators to be aware of each other. It doesn't work when composing with an arbitrary generator.

Yep, a new composing api is in experimental, it will be enable composing with arbitrary generator.
But it's not backward compatible.
https://github.com/mshima/generators/blob/3dead1692fd2716048c4282f5fe846d4627c88da/%40mshima/generator-generator/generators/app/index.js#L38-L89

Should be enabled by yo --experimental.