How to query with orderByKey in combination with startAt/endAt methods?

[Sulomus]

My problem:

I am trying to read JSON object from Firebase Realtime database filtered based on their KEY values.

What I have tried:

• KEY values of the object represents TIMESTAMPS in seconds. I want the Query to filter data that are less then some given value (in m use case it will be currentTime-30seconds).
• My problem is that I can orderByKey without problem using following code:

        QueryFilter query;
        query.orderBy("$key").limitToFirst(10);
        Serial.printf("JSON data: %s\n",  Firebase.RTDB.getJSON(&fb_do, "/trends/GC01/", &query, &json) ? fb_do.to<FirebaseJson>().raw() : fb_do.errorReason().c_str());

• With code above I get first 10 entries in the Firebase.

Now I wanted to add .startAt() and endAt() functions like so:

        QueryFilter query;
        query.orderBy("$key").startAt(0).endAt(1643715327).limitToFirst(10);
        Serial.printf("JSON data: %s\n",  Firebase.RTDB.getJSON(&fb_do, "/trends/GC01/", &query, &json) ? fb_do.to<FirebaseJson>().raw() : fb_do.errorReason().c_str());

But I end up getting this error:
JSON data: Provided key index type is invalid, must be string

So i fixed the values to strings like so: .startAt("0").endAt("1643715327") and now I am getting this error:
Constraint key field must be a valid key name

Additional info:

• I have looked into REST API Firebase docs here and here but couldn't find anything that would help me.
• I started similar discussion regarding deleteNodesByTimestamp method. But I came to the conclusion after testing that more accurate discussion should be in place.

This is structure of my database:

[mobizt]

$key refers to key or node name which is string.

The value you assigned to the functions orderBy, startAt and endAt argument should be string like this

query.orderBy("$key").startAt("0").endAt("1643715327").limitToFirst(10);

The function deleteNodesByTimestamp works on the node value as it expect integer of timestamp as argument.

Edit:
I have to update deleteNodesByTimestamp to treat the wild card $key properly.

[Sulomus]

Thank you for your answer! :)

For now I will be deleting data manually. I am kinda new to the openSourceCommunity and to this library so I don't know if I can help with some changes that you are talking about ...

I don't wanna sound silly but when we could be seeing this update?

[mobizt]

I'm busy now and update may be available in few days or next week.

[mobizt]

Sorry for late update, the library was update for days with this issue fixed.

[Sulomus]

Thank you a lot! Right now I am focusing on different project.

When I will come back to this one I will immediately test it out :)