Generating and deep nested level collection ID in advance in Firestore?

I am trying to achieve creating the ID of a nested collection in advance the surfaceLevelDocId works fine and will generate an id, however, the second implementation should generate another id for the collection that will be nested below the first one (surfaceLevelDocId) but I am getting the following error

> Error FirebaseError: Invalid collection reference. Collection references must have an odd number of segments

the idea is I am setting all of those using a batch later on,
what I did try to add an argument that has nothing to do with anything like ('testData') it worked it gave me a random id but simply is not related to the real path by any means, and I am afraid that could have side effects (like duplicate ids later)
my point here is to generate an id for the newly nested collection that will adhere to the database ids

or something similar to

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const collectionRef = firebaseApp.firestore().collection("YOUR_COLLECTION_NAME");
const collectionId = collectionRef.generateId();

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<!-- begin snippet: js hide: false console: true babel: false -->

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// data-external/${uid}/data
 const externalDoc = doc(fireStore, 'data-external/${uid}/');
// Important: Generated firebase docs ids up-front
const surfaceLevelDocId = doc(collection(externalDoc, 'data')).id;
const nestedLevelDocId = doc(collection(externalDoc, 'data', surfaceLevelDocId)).id;
console.log('nestedLevelDocId', nestedLevelDocId);

<!-- end snippet -->

As @DougStevenson mentioned in his comment, there is nothing built in that can help you generate IDs for the collections. The only function that exists is called doc() but it generates IDs for documents, not for collections. Besides that, when it comes to queries, you have to know the names of the collections/sub-collections before time. Having random names for the collections will make the queries impossible to be performed. You might think, I can list all collection names and go ahead with the queries, but that is not possible when it comes to mobile and web clients. That is possible only with the Node.js admin clients where you'll be able to find a listCollections() function.

If you need uniqueness, then you should consider adding the data in documents using unique IDs, since that's the way Firestore is designed. If that's the requirement and it's mandatory to use random IDs for collection names, then it doesn't matter what mechanism you use. It can be Firestore's mechanism or any other mechanism of yours. However, I recommend against it.