Docs: how to mixin from local file?

[bestickley]

Hi, thanks so much for this library! Has really helped cdk-nextjs offer a flexible/customizable L3 construct to deploy Next.js on AWS.

Given the example from the docs:

new ProjenStruct(project, { name: 'MyProjectOptions' })
  .mixin(Struct.fromFqn('projen.typescript.TypeScriptProjectOptions'))
  .omit('sampleCode', 'projenrcTs', 'projenrcTsOptions');

How could I adjust this example to create a new interface from a local file like:

new ProjenStruct(project, { name: 'MyProjectOptions' })
  .mixin(Struct.fromLocal('./my/file/path/TypeScriptProjectOptions.ts'))
  .omit('sampleCode', 'projenrcTs', 'projenrcTsOptions');

[mrgrain]

Thanks for the kind words @bestickley I'm glad it is helping!

Regarding your suggestion, I'm not sure that's possible. jsii-struct-builder is using a jsii assembly for reflection on existing interfaces. What you are suggesting is pointing to a raw TS file that could contain anything! Even if we assume that it's just an interface, we would now need to reflect on it and that's kind-of difficult. At least not something I would want to implement in this package. Maybe there are existing tools that can provide this?

Taking one step back, may I ask what you are trying to achieve with it?

[bestickley]

@mrgrain, ah I see. I didn't know this package relied on jsii assembly for reflection of existing interfaces. In cdk-nextjs project linked above, I'm exposing an overrides property on the props of the main construct: Nextjs. I'm using this package to create optional interfaces for CDK Prop types used like FunctionProps, DistributionProps etc so we don't have to use any. I'd also like to offer overrides for constructs created locally in this package like NextjsBucketDeployment which is is used in NextjsServer and NextjsStaticAssets. I didn't think I could use Struct.fromFqn to reference that construct so that's why I created this issue.

[mrgrain]

Hm, I see. So something you actually can do, is reference a FQN from the local assembly. E.g.: Struct.fromFqn('cdk-nextjs.NextjsBucketDeployment'). Only thing to consider is that there's a bootstrapping issue because you need the local .jsii to be already available. 🤔

[bestickley]

Oh I see. I thought Struct.fromFqn looked in node_modules so that wouldn't work. Yes, I would have a circular dependency issue :/

[bestickley]

Whoops, didn't mean to close.

[mrgrain]

I thought Struct.fromFqn looked in node_modules so that wouldn't work

Haha yeah. I only implemented that recently: #159

[bestickley]

Haha, well I appreciate you implementing that! Any ideas on how to get around bootstrap issue?

[mrgrain]

Any ideas on how to get around bootstrap issue?

You will have to run projen compile first, which unlike projen build doesn't do a projen default at the start.

[mrgrain]

Otherwise you could define all your interfaces (even the completely new ones) with jsii-struct-builder. That is possibly a bit annoying & manual, but would give you a single source of truth.

[bestickley]

@mrgrain, I think I'll try to modify the GitHub action to run projen compile first instead of just running projen build. Is there a simple or documented way to do that?

Here is an example of our GitHub Action (failing because I need to run projen compile first): https://github.com/jetbridge/cdk-nextjs/actions/runs/7171276028/job/19525876169?pr=181

[mrgrain]

Not this specifically, but I reckon you could patch the workflow files directly using the low level API:

https://projen.io/escape-hatches.html#object-file-patches

[bestickley]

Worked perfectly. Thanks so much, @mrgrain!