Support for unique columns

[privatenumber]

Case

Feature request

Request

I understand a pre hook can be made but would be nice if there is a unique: true or a compound unique array in the schema.

[privatenumber]

Can work on a PR if feature request is approved.

[pubkey]

Hi @hirokiosame
The problem with unique fields is that we have a distributed database which can, or cannot be in sync with other instances.
This makes it very hard to enforce unique fields. For example if you use a unique value in document A and after some time you go online and sync again with a couchdb-server, it may happen that there is a document B with the same value.

There is this good proposal on stackoverflow on how to enforce unique fields and produce a conflict which can be handled if the same value is used.

I do not think there is a good way to generally solve this, so just creating a unique: true-flag and check the local instance if there is a other doc with that value, will give a wrong impression of security.

[privatenumber]

Interesting case. Thanks for the info.

So, even adding a hook to pre-insert to check if the row already exists wouldn't cut it huh?

Is it possible to implement a soft-unique feature with the caveat of not being unique when the database is configured to sync? In my case, I am not syncing my rxdb instance.

[pubkey]

@hirokiosame
I will not add a misleading feature to rxdb. If you know that you do not use the replication, add a preInsert hook that checks for this.
You can always add own field to the schema and therefore just add a unique field, parse it and run the check inside of the hook. Please do not forget to use a proper index, otherwise it will slow down your massively.