From 1ade33491f2e6bdd37e645c4d39394e2654b53aa Mon Sep 17 00:00:00 2001
From: Antony Rizzitelli <rizzitelli.antony@pm.me>
Date: Mon, 2 Nov 2026 20:58:04 +0100
Subject: [PATCH] fix(database): resolve a table update through its type to the
 modified count

Reading the result of `update` through its type (`ReturnType<typeof table.update>`) took the last overload, whose conditional return resolved to `any`. The overloads are reordered so that the document overload, which returns `Query<number>`, is the one a type-level read sees. Calls type exactly as before.
---
 src/staged-query/selection.ts   | 24 ++++++++++++++++++------
 src/tests/helpers/same-type.ts  |  7 +++++++
 src/tests/update_result.test.ts | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 6 deletions(-)
 create mode 100644 src/tests/update_result.test.ts

diff --git a/src/staged-query/selection.ts b/src/staged-query/selection.ts
index 12887b7..b7b0981 100644
--- a/src/staged-query/selection.ts
+++ b/src/staged-query/selection.ts
@@ -32,15 +32,21 @@ function isUpdater<T, U>(
  */
 export class SingleSelection<T> extends Datum<T> {
   /**
-   * Update fields of this selection with the given values
+   * Update fields of this selection with values computed from each document
    *
-   * @param document Partial document with new values
+   * @param document Function building the partial document from the current one
    * @returns Number of modified documents
    */
-  public update(document: DeepPartial<T> & object): Query<number>;
   public update<U>(
     document: (val: ValueProxy<T>) => U,
   ): ExtractType<U> extends DeepPartial<T> ? Query<number> : never;
+  /**
+   * Update fields of this selection with the given values
+   *
+   * @param document Partial document with new values
+   * @returns Number of modified documents
+   */
+  public update(document: DeepPartial<T> & object): Query<number>;
   public update<U>(
     document: (DeepPartial<T> & object) | ((val: ValueProxy<T>) => U),
   ) {
@@ -90,15 +96,21 @@ export class SingleSelection<T> extends Datum<T> {
  */
 export class Selection<T> extends Stream<T> {
   /**
-   * Update fields of this selection with the given values
+   * Update fields of this selection with values computed from each document
    *
-   * @param document Partial document with new values
+   * @param document Function building the partial document from the current one
    * @returns Number of modified documents
    */
-  public update(document: DeepPartial<T> & object): Query<number>;
   public update<U>(
     document: (val: ValueProxy<T>) => U,
   ): ExtractType<U> extends DeepPartial<T> ? Query<number> : never;
+  /**
+   * Update fields of this selection with the given values
+   *
+   * @param document Partial document with new values
+   * @returns Number of modified documents
+   */
+  public update(document: DeepPartial<T> & object): Query<number>;
   public update<U>(
     document: (DeepPartial<T> & object) | ((val: ValueProxy<T>) => U),
   ) {
diff --git a/src/tests/helpers/same-type.ts b/src/tests/helpers/same-type.ts
index 695c559..5555e93 100644
--- a/src/tests/helpers/same-type.ts
+++ b/src/tests/helpers/same-type.ts
@@ -4,3 +4,10 @@ export type Same<A, B> = [A] extends [B]
     ? true
     : false
   : false;
+
+/** Resolves to `true` when `A` is `any`, else to `false`. `Same` cannot tell, as `any` is assignable both ways. */
+type IsAny<A> = 0 extends 1 & A ? true : false;
+
+/** Like `Same`, but `any` on either side resolves to `false`. */
+export type Exact<A, B> =
+  IsAny<A> extends true ? false : IsAny<B> extends true ? false : Same<A, B>;
diff --git a/src/tests/update_result.test.ts b/src/tests/update_result.test.ts
new file mode 100644
index 0000000..eb41098
--- /dev/null
+++ b/src/tests/update_result.test.ts
@@ -0,0 +1,33 @@
+import { expect } from "chai";
+import { Schema, type Query } from "..";
+import type { Exact } from "./helpers/same-type";
+import { Vehicle } from "./datasets/vehicles";
+
+const schema = new Schema<{ vehicles: Vehicle }>("test-update-result", {
+  vehicles: Vehicle,
+});
+const vehicles = schema.instance("default").table("vehicles");
+
+describe("Update result", () => {
+  it("Resolves an update call to a query of the modified count", () => {
+    const viaDocument = vehicles.get("a").update({ price: 1 });
+    const viaUpdater = vehicles.get("a").update(() => ({ price: 2 }));
+    const document: Exact<typeof viaDocument, Query<number>> = true;
+    const updater: Exact<typeof viaUpdater, Query<number>> = true;
+    expect(document && updater).to.equal(true);
+  });
+
+  it("Resolves the update of a table, read through its type, to the modified count", () => {
+    const table: Exact<
+      Awaited<ReturnType<ReturnType<typeof vehicles.update>["run"]>>,
+      number
+    > = true;
+    const single: Exact<
+      Awaited<
+        ReturnType<ReturnType<ReturnType<typeof vehicles.get>["update"]>["run"]>
+      >,
+      number
+    > = true;
+    expect(table && single).to.equal(true);
+  });
+});