APIs Explorer's Firestore's projects.databases.documents.list has incorrect regex - google-cloud-firestore

Question

Summary: APIs Explorer "Try this API" for projects.databases.documents.list appears (!?) to have an overly restrictive/incorrect regex on parent and requirement on collectionId.
Neither gcloud firestore nor firebase firestore: provides functionality to list collections, I'm planning to write a simple app to do so.
As always, I explored the APIs methods using the excellent APIs Explorer but the projects.databases.documents.list "Try this API" appears (!?) to have an overly restrictive|incorrect regex on parent.
The documentation correctly states that:
https://firestore.googleapis.com/v1/{parent=projects/*/databases/*/documents/*/**}/{collectionId}
And:
Required. The parent resource name. In the format:
projects/{project_id}/databases/{database_id}/documents or
projects/{project_id}/databases/{database_id}/documents/{document_path}.
For example: projects/my-project/databases/my-database/documents or projects/my-project/databases/my-database/documents/chatrooms/my-chatroom
Using Google's first format example: projects/my-project/databases/my-database/documents does not work:
APIs Explorer only accepts the second format example for parent but then requires a value for collectionId which may not be desired:
APIs Explorer appends collectionId to the parent to from the URL. In the case of parent ending /documents (which isn't permitted), this would make sense to access the chatrooms collection or in the case that parent ends /documents/chatrooms/my-chatroom to then get the messages collection (with my-chatroom) but the requirement prohibits using APIs Explorer (!) to query projects/my-project/databases/my-database/documents/chatrooms; collectionId is required and would need to be chatrooms but a parent of projects/my-project/databases/my-database/documents is not permitted.
Using one of my projects (${PROJECT}) and (default) for {database_id}, I can use the documentation's examples correctly in curl:
TOKEN=$(gcloud auth print-access-token)
PROJECT=...
PARENT=projects/${PROJECT}/databases/(default)/documents
COLLECTION=...
curl \
--header "Authorization: Bearer ${TOKEN}" \
--header 'Accept: application/json' \
--write-out '%{response_code}' \
--output /dev/null \
--silent \
https://firestore.googleapis.com/v1/${PARENT}/${COLLECTION}
200
The APIs works correctly navigating down through subcollections too.
Posting this here in the hopes that, if APIs Explorer is indeed incorrect, fixing it can help other developers not encounter this issue and be discouraged.
Note: Since I'm posting feedback, the tool doesn't correctly adjust cURL, HTTP or JavaScript generated examples to reflect the checkbox value on "API Key"; when the "API Key" is deselected, the parameter should not be included in the calls.

Answer 1

It seems to be a problem with the regular expression in the API explorer. I need to enter the parent as projects/fire-template-24/databases/(default)/documents/users/ (including the forward slash) and also enter the collectionId as it's required (users in my case). This seems to be making a query at:
https://[GOOGLE+APIS_URL]/projects/[ID]/databases/(default)/documents/users//users?key=[API_KEY]
This returns an error about the extra trailing slash which the API explorer forced me to add and collectionId field is also appended to it with another /.
The following regular expression seems to be working:
^projects\/[^/]+\/databases\/[^/]+\/documents(\/[^/]+(\/[^/]+\/[^/]+)*)$
The above RegEx doesn't required a forward slash in parent and matches a collection path only. If the collectionId is removed then it should work. Working example of the RegEx can be found here.

Answer 2

I could also observe the same in the API explorer page. I observed that there is an existing issue in the Public Issue Tracker for the same. As mentioned in the #2 comment of the issue, this issue report has been forwarded to the Firestore Engineering team to investigate, but there is no ETA for a resolution. I would suggest you star the issue so that you will get notified whenever there is any update on the issue.