TransactionWithMutations

type TransactionWithMutations<T, TOperation, TCollection> = Omit<Transaction<T>, "mutations"> & object;

Defined in: packages/db/src/types.ts:156

Utility type for a Transaction with at least one mutation This is used internally by the Transaction.commit method

Type Declaration

mutations

mutations: NonEmptyArray<PendingMutation<T, TOperation, TCollection>>;

We must omit the mutations property from Transaction<T> before intersecting because TypeScript intersects property types when the same property appears on both sides of an intersection.

Without Omit:

Transaction<T> has mutations: Array<PendingMutation<T>>
The intersection would create: Array<PendingMutation<T>> & NonEmptyArray<PendingMutation<T, TOperation>>
When mapping over this array, TypeScript widens TOperation from the specific literal (e.g., "delete") to the union OperationType ("insert" | "update" | "delete")
This causes PendingMutation<T, OperationType> to evaluate the conditional type original: TOperation extends 'insert' ? {} : T as {} | T instead of just T

With Omit:

We remove mutations from Transaction<T> first
Then add back mutations: NonEmptyArray<PendingMutation<T, TOperation>>
TypeScript can properly narrow TOperation to the specific literal type
This ensures mutation.original is correctly typed as T (not {} | T) when mapping