Drizzle Team•9mo ago

How to type a function with column key of table

I can't get this to type correctly. I want field to be a column of table, but typescript keeps saying Type 'Field' cannot be used to index type 'TTable'. What's the best way to do this?

type GetColumnKeys<TTable extends Table> = keyof {
  [K in keyof TTable as K extends keyof TTable['_']['columns'] ? K : never]: true
}

async function getOptions<
  TTable extends Table,
  Field extends GetColumnKeys<TTable>
>(table: TTable, field: Field) {
  const column = table[field]
  const result = await drizzleDb
    .selectDistinct({
      option: column
    })
    .from(table)
    .orderBy(column)
  return result.map((i) => String(i.option))
}

type GetColumnKeys<TTable extends Table> = keyof {
  [K in keyof TTable as K extends keyof TTable['_']['columns'] ? K : never]: true
}

async function getOptions<
  TTable extends Table,
  Field extends GetColumnKeys<TTable>
>(table: TTable, field: Field) {
  const column = table[field]
  const result = await drizzleDb
    .selectDistinct({
      option: column
    })
    .from(table)
    .orderBy(column)
  return result.map((i) => String(i.option))
}

5 Replies

Angelelz•9mo ago

How about:

Field extends keyof TTable & string

Field extends keyof TTable & string

JustTheSyme•9mo ago

@Angelelz I get an error trying to pass column to option with that:

1. Type 'TTable[Field]' is not assignable to type 'SQL<unknown> | Aliased<unknown> | PgColumn<ColumnBaseConfig<ColumnDataType, string>, {}, {}> | PgTable<TableConfig> | SelectedFieldsFlat<...>'.
     Type 'TTable[keyof TTable & string]' is not assignable to type 'SQL<unknown> | Aliased<unknown> | PgColumn<ColumnBaseConfig<ColumnDataType, string>, {}, {}> | PgTable<TableConfig> | SelectedFieldsFlat<...>'.
       Type 'TTable[string]' is not assignable to type 'SQL<unknown> | Aliased<unknown> | PgColumn<ColumnBaseConfig<ColumnDataType, string>, {}, {}> | PgTable<TableConfig> | SelectedFieldsFlat<...>'.
         Type 'TTable[string]' is not assignable to type 'PgTable<TableConfig>'.
           Type 'TTable[keyof TTable & string]' is not assignable to type 'PgTable<TableConfig>'.
             Type 'TTable[Field]' is not assignable to type 'PgTable<TableConfig>'.
               Type 'TTable[keyof TTable & string]' is not assignable to type 'PgTable<TableConfig>'.
                 Type 'TTable[string]' is not assignable to type 'PgTable<TableConfig>'. [2322]

1. Type 'TTable[Field]' is not assignable to type 'SQL<unknown> | Aliased<unknown> | PgColumn<ColumnBaseConfig<ColumnDataType, string>, {}, {}> | PgTable<TableConfig> | SelectedFieldsFlat<...>'.
     Type 'TTable[keyof TTable & string]' is not assignable to type 'SQL<unknown> | Aliased<unknown> | PgColumn<ColumnBaseConfig<ColumnDataType, string>, {}, {}> | PgTable<TableConfig> | SelectedFieldsFlat<...>'.
       Type 'TTable[string]' is not assignable to type 'SQL<unknown> | Aliased<unknown> | PgColumn<ColumnBaseConfig<ColumnDataType, string>, {}, {}> | PgTable<TableConfig> | SelectedFieldsFlat<...>'.
         Type 'TTable[string]' is not assignable to type 'PgTable<TableConfig>'.
           Type 'TTable[keyof TTable & string]' is not assignable to type 'PgTable<TableConfig>'.
             Type 'TTable[Field]' is not assignable to type 'PgTable<TableConfig>'.
               Type 'TTable[keyof TTable & string]' is not assignable to type 'PgTable<TableConfig>'.
                 Type 'TTable[string]' is not assignable to type 'PgTable<TableConfig>'. [2322]

Angelelz•9mo ago

I would just cast it and call it a day:

const column = table[field] as AnyPgColumn

const column = table[field] as AnyPgColumn

JustTheSyme•9mo ago

@Angelelz I found that this works fine with typesafety

async function getOptions<
  TTable extends Table,
  Field extends keyof TTable['_']['columns']
>(table: TTable, field: Field) {
  const columns = getTableColumns(table)
  const column = columns[field]
  if (!column) {
    return []
  }
  const result = await drizzleDb
    .selectDistinct({
      option: column
    })
    .from(table)
    .orderBy(column)
  return result.map((i) => String(i.option))
}

async function getOptions<
  TTable extends Table,
  Field extends keyof TTable['_']['columns']
>(table: TTable, field: Field) {
  const columns = getTableColumns(table)
  const column = columns[field]
  if (!column) {
    return []
  }
  const result = await drizzleDb
    .selectDistinct({
      option: column
    })
    .from(table)
    .orderBy(column)
  return result.map((i) => String(i.option))
}

But I wish I didn't have to make a call to getTableColumns to make it work. It's not too bad, though.

Angelelz•9mo ago

This is a great idea! I don't see too many downsides to this

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How to type a function with column key of table