Kysely•11mo ago

Ad hoc custom column type

Hello, we have a table that on the database level, the column is a string type, but on the typescript level, the type is a Type literal union. Is there any way we can ad hoc type a column to a type we know during select queries and insert statements?

Solution:

Just give that type for the column in the table interface.

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6 Replies

Igal•11mo ago

Hey 👋 Can you provide an example of what you mean?

bombillazo•11mo ago

Lest say I have this:

type X = 'foo' | 'bar' | 'baz';

await db
.selectFrom('my_table')
.select(['a','b','c')
.execute();

type X = 'foo' | 'bar' | 'baz';

await db
.selectFrom('my_table')
.select(['a','b','c')
.execute();

At the DB level, b is a string, but I want to type is as type X, how can I do that in my select query?

Solution

koskimas•11mo ago

Just give that type for the column in the table interface.

bombillazo•11mo ago

We aare using kysely-codegen, so there is no way to do this like one could do with a helper function like selectFrom('my_table').select<MyType>(['b'])...?

koskimas•11mo ago

You can use $narrowType https://kyse.link/?p=s&i=MkGH92pVw6mxm9xdcAwE

Igal•11mo ago

Look for overrides in kysely-codegen, if its not supported, submit an issue if one doesn't exist. If you're on postgres, try kanel-kysely

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Ad hoc custom column type