Core Backend : ES Modules

[pankhur94]

No description provided.

[pankhur94]

We changed our core-bentley package to module system, while re building the repo, Bentley package builds successfully, however, some depenedent package fail to build with the following issue

I tried providing different types file for both cjs and esm build using export map,

"exports": {
    ".": {
      "require": {
        "types": "./lib/cjs/core-bentley",
        "default": "./lib/cjs/core-bentley.js"
      },
      "import": {
        "types": "./lib/esm/core-bentley",
        "default": "./lib/esm/core-bentley.js"
      }
    }
  }

, but the issue still persists.

[mayank99]

I'm not familiar with this codebase, but it looks like a TypeScript issue. The packages that are consuming @itwin/core-bentley are expecting some types (likely CJS) that don't match what is being imported (likely ESM).

[grigasp]

We changed our core-bentley package to module system, while re building the repo, Bentley package builds successfully, however, some depenedent package fail <..>

I'm not seeing this issue with presentation-backend, but I do with presentation-frontend package, and it's also related to BeEvent as yours:

src/test/PresentationManager.test.ts:97:63 - error TS2322: Type 'import("/home/grigas/itwinjs-core/core/bentley/lib/esm/BeEvent", { with: { "resolution-mode": "import" } }).BeEvent<(_imodel: import("/home/grigas/itwinjs-core/core/frontend/lib/cjs/IModelConnection").IModelConnection) => void>' is not assignable to type 'import("/home/grigas/itwinjs-core/core/bentley/lib/cjs/BeEvent").BeEvent<(_imodel: import("/home/grigas/itwinjs-core/core/frontend/lib/cjs/IModelConnection").IModelConnection) => void>'.
  Types have separate declarations of a private property '_listeners'.

From the paths in the error you can clearly see that BeEvent that tests use is from esm, but IModelConnection and its onClose BeEvent type are coming from cjs. And the tests are trying to assign an instance of ESM BeEvent to a property that is CJS BeEvent. From TS perspective these are 2 different types, and it rightfully complains.

I think this is happening because, with your changes, core-bentley package now properly supports ESM, and that makes our tests use ESM instead of CJS. On the other hand, core-frontend doesn't have proper ESM support, and the tests still use its CJS version, and all its dependencies are also from CJS, including BeEvent from core-bentley.

So I think you'll have to start from the top and then move deeper into the stack. E.g. core-bentley can be fixed only when you fix all packages that have dependency on it.

[pankhur94]

We changed our core-bentley package to module system, while re building the repo, Bentley package builds successfully, however, some depenedent package fail <..>

I'm not seeing this issue with presentation-backend, but I do with presentation-frontend package, and it's also related to BeEvent as yours:

src/test/PresentationManager.test.ts:97:63 - error TS2322: Type 'import("/home/grigas/itwinjs-core/core/bentley/lib/esm/BeEvent", { with: { "resolution-mode": "import" } }).BeEvent<(_imodel: import("/home/grigas/itwinjs-core/core/frontend/lib/cjs/IModelConnection").IModelConnection) => void>' is not assignable to type 'import("/home/grigas/itwinjs-core/core/bentley/lib/cjs/BeEvent").BeEvent<(_imodel: import("/home/grigas/itwinjs-core/core/frontend/lib/cjs/IModelConnection").IModelConnection) => void>'.
  Types have separate declarations of a private property '_listeners'.

From the paths in the error you can clearly see that BeEvent that tests use is from esm, but IModelConnection and its onClose BeEvent type are coming from cjs. And the tests are trying to assign an instance of ESM BeEvent to a property that is CJS BeEvent. From TS perspective these are 2 different types, and it rightfully complains.

I think this is happening because, with your changes, core-bentley package now properly supports ESM, and that makes our tests use ESM instead of CJS. On the other hand, core-frontend doesn't have proper ESM support, and the tests still use its CJS version, and all its dependencies are also from CJS, including BeEvent from core-bentley.

So I think you'll have to start from the top and then move deeper into the stack. E.g. core-bentley can be fixed only when you fix all packages that have dependency on it.

We are actually moving other way round, for ex, we start with the package with least dependencies i.e. core-bentley, core-geometry and upwards. But yes, I do agree that the reason you explained is correct. As soon as we convert all the dependencies of presentation-backend i.e. core-bentley, core-backend etc to esm, the issue is resolved.