Kysely•3y ago

How do I create a helper to be used on a select array of fields?

I want to create a toBool helper to convert from tinyint, however I'm lost on the type I need to pass to get autocomplete of the possible fields in the select

import { sql } from 'kysely'

export const toBool = (
  field: string // what type should I add here?
) => {
  return sql<boolean>`IF(${field} > 0, true, false)`
}

import { sql } from 'kysely'

export const toBool = (
  field: string // what type should I add here?
) => {
  return sql<boolean>`IF(${field} > 0, true, false)`
}

import { sql } from 'kysely'

export const toBool = (
  field: string // what type should I add here?
) => {
  return sql<boolean>`IF(${field} > 0, true, false)`
}

import { sql } from 'kysely'

export const toBool = (
  field: string // what type should I add here?
) => {
  return sql<boolean>`IF(${field} > 0, true, false)`
}

Solution

I think checking equality to 0 would make this safer (and swapping true/false order), as tinyint can be negative.

Jump to solution

thelinuxlichOP•10/19/23, 1:03 AM

I ended up with this implementation, am I correct?

import { sql, type ExpressionWrapper } from 'kysely'

export const toBool = <DB, TB extends keyof DB, T>(
  field: ExpressionWrapper<DB, TB, T>
) => {
  return sql<boolean>`IF(${field} > 0, true, false)`
}


// usage

select(eb => [toBool(eb.ref('field')).as('alias')])

import { sql, type ExpressionWrapper } from 'kysely'

export const toBool = <DB, TB extends keyof DB, T>(
  field: ExpressionWrapper<DB, TB, T>
) => {
  return sql<boolean>`IF(${field} > 0, true, false)`
}


// usage

select(eb => [toBool(eb.ref('field')).as('alias')])

Solution

Igal•11/2/23, 5:04 PM

I think checking equality to 0 would make this safer (and swapping true/false order), as tinyint can be negative.