add findOne() to query builder

[fcannizzaro]

Hi! I've implemented the findOne() in the query builder (#182) for db and react-db.

When findOne() is chained in the query builder, I store a single variable in the context (extending also the context type for the inference) that is then inherited from the collection config to allow the data getter to return a single row or an array.

I also tested both db/test and react-db/test (by adding also a dedicated test for this feature).

LMK if it's ok to do like this or if you have some better ideas.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 6196879

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[obeattie]

I'd definitely find an API like this to retrieve just a single row helpful.