Fix: Mongoose types incorrect for when includeResultMetadata: true is set

[prathamVaidya]

Summary

Fixed Issue #13987
Mongoose Version: 8.0

When includeResultMetadata is set to true. The document parameter in post middleware can also be ModifyResult<>.

Functions that support includeResultMetadata option are : findOneAndUpdate, findByIdAndUpdate, findOneAndReplace, findByIdAndDelete, and findOneAndDelete.

Changes Done:

• Introduced a separate document type for the post middleware, specifically for these functions, ensuring they also return ModifyResult<>.
• Some of these functions were not returning ModifyResult<> when includeResultMetadata was set to True. I've addressed this by adding appropriate return types.
• In cases where includeResultMetadata is false and no matching document is found in any of these functions, the document parameter in the post middleware is NULL. So I have included NULL as a possible doc type in the middleware parameter.

Examples

import mongoose, { ModifyResult, Query } from "mongoose";

const UserSchema = new mongoose.Schema({
  id: String,
  username: String,
});

UserSchema.post<
  Query<
    mongoose.HydratedDocument<mongoose.InferSchemaType<typeof UserSchema>>,
    mongoose.InferSchemaType<typeof UserSchema>
  >
>("findOneAndDelete", function (doc) {
// doc can be NULL | QueryResultType<T> | ModifyResult<QueryResultType<T>>
  if (doc && "value" in doc) {
    console.debug("DELETE VALUE = ", doc.value);
  }
});

const UserModel = mongoose.model("User", UserSchema);

async function main() {
  await mongoose.connect(`mongodb://localhost:27017/mongoose-test`);

  await mongoose.connection.dropDatabase();

  const doc = new UserModel({ username: "user1" });

  await doc.save();

  const upsertResult = await UserModel.findOneAndDelete(
    {username: "user1"},
    {
      includeResultMetadata: true,
    }
  ).exec();

  if (upsertResult) {
    console.log("Result=", upsertResult.value); // it has type set to ModifyResult now
  } else {
    console.log("NULL", upsertResult);
  }
}

main();

I have fixed the issue for v8.0. If the solution is acceptable then I will also do it for v7.4 that was originally specified in the Issue. @hasezoey

[vkarpov15]

Thanks for your PR. Please fix lint, add a test case, and address the comments in this review 👍

[hasezoey]

Looks good to me, though some minor questions / suggestions.

also does someone know why the tests are not running for the latest commits?

[vkarpov15]

Can you please fix merge conflicts?

[prathamVaidya]

Fixed Merge Conflicts ✅

[vkarpov15]

LGTM, thanks 👍