implement type predicates for query builders

[garymathews]

• Similar to the existing SelectQueryBuilder.isSelectQueryBuilder property, implemented:
  • InsertQueryBuilder.isInsertQueryBuilder
  • UpdateQueryBuilder.isUpdateQueryBuilder
  • DeleteQueryBuilder.isDeleteQueryBuilder
  • MergeQueryBuilder.isMergeQueryBuilder
• Implemented type predicate methods for each query builder:
  • isSelectQueryBuilder(qb)
  • isInsertQueryBuilder(qb)
  • isUpdateQueryBuilder(qb)
  • isDeleteQueryBuilder(qb)
  • isMergeQueryBuilder(qb)
• Added AnyQueryBuilder type

Examples

import { AnyQueryBuilder, isSelectQueryBuilder } from 'kysely'

function explainSelect<DB, TB extends keyof DB, O>(qb: AnyQueryBuilder<DB, TB, O>) {
  if (isSelectQueryBuilder(qb)) {
    // TypeScript determines `qb` as being of type `SelectQueryBuilder` whithin this scope
    return query.explain('json')
  }
  return query
}

import { AnyQueryBuilder, InsertResult, DeleteResult, isInsertQueryBuilder } from 'kysely'

const queries: AnyQueryBuilder<Database, 'person', InsertResult | DeleteResult>[] = [
  db.insertInto('person').values({ first_name: 'Mary', last_name: 'Shelley', gender: 'female' }),
  db.deleteFrom('person').where('first_name', '=', 'Ann'),
  db.insertInto('person').values({ first_name: 'Bram', last_name: 'Stoker', gender: 'male' })
]

// Grab all `InsertQueryBuilder` queries
const insertQueries = queries.filter(isInsertQueryBuilder)
// TypeScript identifies `insertQueries` as being of type `InsertQueryBuilder[]`

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Name	Status	Preview	Comments	Updated (UTC)
kysely	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Apr 21, 2024 9:12am

[garymathews]

@koskimas is this something you're open to adding?

[igalklebanov]

Hey 👋

Thank you! 💪

Can you explain the real-world use of this?