Add unique flag to field block

[mingard]

Some fields such as article title are often required to be unique. Introducing a unique flag should check on matching document field values before accepting/rejecting based on results.

{
  "type": "String",
  "unique": true
}

Alternatively this could be handled in a hook. I will open a ticket for the changes required to achieve this.

[eduardoboucas]

Jeez, I was thinking about this yesterday! It could be part of the validation block, perhaps.

[mingard]

Yes I prefer the idea of being part of validation.

[jimlambie]

An alternative would be to hand this off to the storage engine by using a unique index. Or perhaps by adding validation: { unique: true } a unique index is created automatically.

[mingard]

I like the DB-level concept. Is such a concept supported by all the current Edge DB modules?

Maybe the unique index would be better. Again, if 100% coverage with DBs.

[fra967]

MInd that an index adds load on write operations, you don't necessarily want an index on a field that must be unique. To me this seems more a validation requirement than a DB one.

[mingard]

Would that increased load be more or less than a pre-save match query on every unique field?

I'm happy with either but perhaps we should test both?