How to use different types/schemas for Reads and Writes?

[maxpaleo]

Is there a way to use a different schema for handlers?

Currently, the onInsert handler is typed to take in the same schema params as what the queryFun returns.

In the example below, the usersCollection returns an array of users with id, first_name, last_name and email.

When inserting into the collection, using usersCollection.insert(), the params are identical to the data being returned. But it should be typed as what my actual DB operation requires, in this case:

createUser({
        firstName: item.first_name!,
        lastName: item.last_name!,
        email: item.email!,
      })

I've been through the docs but haven't found a way to retype the inputs for collection handlers. Is this not currently supported?

Below is a full example:

const usersSchema = z.object({
  id: z.string(), // Auto-generate at DB level
  first_name: z.string().nullable().default(null),
  last_name: z.string().nullable().default(null),
  email: z.string().nullable().default(null),
});

export const usersCollection = createCollection(
  queryCollectionOptions({
    queryKey: ["users"],
    queryFn: getUsers,
    queryClient,
    schema: usersSchema,
    getKey: (item) => item.id,
    onInsert: async ({ transaction }) => {
      // ❌ onInsert requires the id to be provided. How can this be changed to take the params of createUser?
      const item = transaction.mutations[0].modified;

      await createUser({
        firstName: item.first_name!,
        lastName: item.last_name!,
        email: item.email!,
      });
    },
  })
);

[KyleAMathews]

Optimistic inserts must take the type of the collection as they'll immediately render so the input must equal the output. If you want a mutator with a different type — I suggest using an action — see https://tanstack.com/db/latest/docs/guides/schemas & https://tanstack.com/db/latest/docs/guides/mutations#creating-custom-actions