MergeContextForJoinCallback | TanStack DB Español

type MergeContextForJoinCallback<TContext, TNewSchema> = Omit<TContext, "schema" | "refsSchema" | "hasJoins" | "joinTypes"> & object;

Defined in: packages/db/src/query/builder/types.ts:1328

MergeContextForJoinCallback - Special context for join condition callbacks

This type creates a context specifically for the onCallback parameter of join operations. The key difference from MergeContextWithJoinType is that NO optionality is applied here.

Why No Optionality? In SQL, join conditions are evaluated BEFORE optionality is determined. Both tables must be treated as available (non-optional) within the join condition itself. Optionality is only applied to the result AFTER the join logic executes.

Example:

.from({ users })
.leftJoin({ orders }, ({ users, orders }) => {
  // users is NOT optional here - we can access users.id directly
  // orders is NOT optional here - we can access orders.userId directly
  return eq(users.id, orders.userId)
})
.where(({ orders }) => {
  // NOW orders is optional because it's after the LEFT JOIN
  return orders?.status === 'pending'
})

The simple intersection (&) merges schemas without any optionality transformation.

Type Declaration

baseSchema

baseSchema: TContext["baseSchema"];

fromSourceName

fromSourceName: TContext["fromSourceName"];

hasJoins

hasJoins: true;

joinTypes

joinTypes: TContext["joinTypes"] extends Record<string, any> ? TContext["joinTypes"] : object & { [K in keyof TNewSchema & string]: "inner" };

refsSchema

refsSchema: RefsSchemaForContext<TContext> & TNewSchema;

schema

schema: TContext["schema"] & TNewSchema;

Type Parameters

TContext

TContext extends Context

TNewSchema

TNewSchema extends ContextSchema