Is there any way to pre-load external files/modules before generating/running typeorm migrations?

Question

I have created a few extensions on some base classes, such as Array to add some functionality that is commonly used throughout our NestJS app. Consider the following example:

We have a declaration in a .d file:

// in src/declarations/array.d.ts

declare interface Array<T> {
  undupe(key?: (e: T) => any): Array<T>; // method that removes duplicate elements from the array
}

And the corresponding implementation:

// src/implementations/array.implementation.ts

Array.prototype.undupe = function (
  this: Array<any>,
  key?: (e: any) => any,
): Array<any> {
  ...
};

In order for this to work, I am also importing src/implementations/array.implementation.ts in our main.ts file.

I am now trying to create a new entity that is importing a file that is using .undupe() somewhere in it an I am getting this error while generating a new migration for it using the typeorm CLI:

$ yarn typeorm migration:generate -n 'SomeMigration'
yarn run v1.22.19
warning ../../package.json: No license field
$ node --require ts-node/register ./node_modules/typeorm/cli.js migration:generate -n 'SomeMigration'
Error during migration generation:
<some-file-path-that-is-imported-in-the-new-entity-file> - error TS2339: Property 'undupe' does not exist on type 'number[]'.

292         .undupe();
             ~~~~~~

error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

I tried specifically importing src/implementations/array.implementation in the file that is being imported, but that did not work.

I saw a similar error while using Jest, but I could easily solve that by specifying src/implementations/array.implementation.ts in the setupFilesAfterEnv field of our jest config json, like this:

{
...
"setupFilesAfterEnv": ["<rootDir>/src/implementations/array.implementation.ts"]
...
}

Is there something similar for TypeOrm? Or does anyone know another workaround to this?

Similar question I found (with no answers)

Answer 1

After some messing around, I found a way to fix this. The issue wasn't with TypeORM, but with node (or ts-node) not including the declaration files, and the compiler complaining that the undupe property does not exist on Array .

Previously, I had in my package.json , the following line:

"typeorm": "node --require ts-node/register ./node_modules/typeorm/cli.js"

I changed this to use ts-node instead:

"typeorm": "ts-node ./node_modules/typeorm/cli.js"

I then had to edit my existing tsconfig.json file to add these lines:

// tsconfig.json
{
  "ts-node": {
    "files": true
  }, 
  "include": ["src/declarations/*"], 
  ... //rest of my ts-config below
}

Alternatively, I also found that this works as well:

// tsconfig.json
{
  "ts-node": {
    "files": true
  }, 
  "files": ["src/declarations/array.d.ts"], 
  ... //rest of my ts-config below
}

Source for the above can be found here .