tweak(db): exists method on database and database model classes

[jaskfla]

We often try a find(), occasionally a count(), and check whether it’s null or 0, respectively just to check existence of a record

> db = new TupaiaDatabase()

> await db.exists('user_account', { first_name: { comparator: 'ilike', comparisonValue: 'jasper' } })
// knex:query SELECT EXISTS((select * from "user_account" where "first_name" ilike $1)); undefined +37s
true

> await db.exists('user_account', { first_name: { comparator: 'ilike', comparisonValue: 'asdf' } })
// knex:query SELECT EXISTS((select * from "user_account" where "first_name" ilike $1)); undefined +4s
false

> await db.exists('project', { code: 'explore' })
// knex:query SELECT EXISTS((select * from "project" where "code" = $1)); undefined +4s
true

[gemini-code-assist]

Summary of Changes

Hello @jaskfla, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new exists method across the database and database model classes. This change provides a more explicit, readable, and potentially more performant way to determine if a record or set of records exists in the database, streamlining common patterns that previously involved find() and checking for null or count() and checking for 0.

Highlights

• New exists method for database models: Introduced an async exists method to DatabaseModel that delegates the call to the underlying database instance, providing a cleaner API for checking record existence.
• Database-level exists implementation: Implemented the async exists method in TupaiaDatabase to efficiently check for record existence using a SELECT EXISTS(?) SQL query, which is generally more performant than COUNT(*) when only existence is needed.

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[gemini-code-assist]

Code Review

This pull request introduces an exists method to both the Database and DatabaseModel classes, providing a more readable and efficient way to check for the existence of a record. The implementation involves using SELECT EXISTS(?) in the database layer and exposing this functionality through the model. This change aims to simplify code and improve readability when checking for record existence.

[chris-bes]

Just 1 suggestion

[chris-bes]

I think we could move this to the BaseDatabase?

[jaskfla]

100% agree! But it doesn't exist on the base branch (this PR is off dev)

Unless you’re itching to use this (I have been), feel free to leave this PR for my return and I will integrate it into BaseDatabase and resolve merge conflicts

[cursor]

Bug: Race condition: Unready DB breaks subquery.

The exists method doesn't await this.find() before passing it to executeSql. When the database connection isn't ready, find returns a Promise-wrapped query via queryWhenConnected, not a Knex query builder. Passing this Promise to connection.raw() as a binding will fail because Knex expects a query builder object for subquery bindings, creating a race condition on startup.