Inserting without an optional index field causes unexpected behavior

[OskarD]

This PR contains:

A BUG REPORT

Describe the problem you have without this PR

Documents inserted with a (not required) empty index field behave unexpectedly

Todos

• Tests
• Documentation
• Typings
• Changelog

[OskarD]

Bonus: This script does not exist

[pubkey]

Thanks for the PR. Indeed it looks like there is a bug. I will check.

[pubkey]

Ok so the query plan looks correct:

"preparedQuery": {
        "query": {
            "selector": {
                "_deleted": {
                    "$eq": false
                }
            },
            "sort": [
                {
                    "id": "asc"
                }
            ],
            "skip": 0
        },
        "queryPlan": {
            "index": [
                "_deleted",
                "numberIndex",
                "id"
            ],
            "startKeys": [
                false,
                -9007199254740991,
                -9007199254740991
            ],
            "endKeys": [
                false,
                "�",
                "�"
            ],
            "inclusiveEnd": true,
            "inclusiveStart": true,
            "sortSatisfiedByIndex": false,
            "selectorSatisfiedByIndex": true
        }
    }

I played around with the generated keyrange but I am not sure if this is even fixable.

[pubkey]

I found out:
As David Fahlander from dexie.js explains here, undefined is not an indexable type. So this cannot be fixed. We should add a check to the dexie.js RxStorage to throw a proper error when this type of schema is used. Just returning wrong results is not a correct behavior.

The premium IndexedDB RxStorage from RxDB does not have this problem because it uses custom index strings, not the composite index keys from native IndexedDB.