From 1efaa1edf85438f64663aa1866a25eb7a9b0d9f0 Mon Sep 17 00:00:00 2001
From: Lee Danilek <lee@convex.dev>
Date: Wed, 20 Nov 2024 11:32:30 -0500
Subject: [PATCH] nice error on nested triggers

---
 .../convex-helpers/server/triggers.test.ts    | 28 +++++++++++++++++++
 packages/convex-helpers/server/triggers.ts    | 10 +++++++
 2 files changed, 38 insertions(+)

diff --git a/packages/convex-helpers/server/triggers.test.ts b/packages/convex-helpers/server/triggers.test.ts
index 4028ad23..9c6fb371 100644
--- a/packages/convex-helpers/server/triggers.test.ts
+++ b/packages/convex-helpers/server/triggers.test.ts
@@ -48,9 +48,20 @@ export const createUser = mutation({
   },
 });
 
+export const incorrectMutationCallingOtherMutation = mutation({
+  args: { firstName: v.string(), lastName: v.string() },
+  handler: async (ctx, args) => {
+    // createUser is a mutation so you aren't supposed to call it like this.
+    // But if you happen to do it anyway, we should throw an informative error.
+    const id = await createUser(ctx, args);
+    return id;
+  },
+});
+
 const testApi: ApiFromModules<{
   fns: {
     createUser: typeof createUser;
+    incorrectMutationCallingOtherMutation: typeof incorrectMutationCallingOtherMutation;
   };
 }>["fns"] = anyApi["triggers.test"] as any;
 
@@ -65,3 +76,20 @@ test("trigger denormalizes field", async () => {
     expect(user!.fullName).toStrictEqual("John Doe");
   });
 });
+
+test("incorrect mutation calling other mutation", async () => {
+  const t = convexTest(schema, modules);
+  await expect(t.mutation(testApi.incorrectMutationCallingOtherMutation, {
+    firstName: "John",
+      lastName: "Doe",
+    }),
+  ).rejects.toThrow(
+    new RegExp(
+      `Triggers\\.wrapDB called multiple times in a single mutation\\.\\s+` +
+        `Not allowed due to potential deadlock\\.\\s+` +
+        `Call it once in a single \`customMutation\`\\.\\s+` +
+        `Do not call mutations directly as functions\\.\\s+` +
+        `See https:\\/\\/docs\\.convex\\.dev\\/production\\/best-practices\\/#use-helper-functions-to-write-shared-code`,
+    ),
+  );
+});
diff --git a/packages/convex-helpers/server/triggers.ts b/packages/convex-helpers/server/triggers.ts
index 4da55af3..1248eed3 100644
--- a/packages/convex-helpers/server/triggers.ts
+++ b/packages/convex-helpers/server/triggers.ts
@@ -90,6 +90,15 @@ export class Triggers<
   }
 
   wrapDB = <C extends Ctx>(ctx: C): C => {
+    if (wrapDBCalled) {
+      throw new Error(
+        `Triggers.wrapDB called multiple times in a single mutation. Not allowed due to potential deadlock.
+        Call it once in a single \`customMutation\`.
+        Do not call mutations directly as functions.
+        See https://docs.convex.dev/production/best-practices/#use-helper-functions-to-write-shared-code`,
+      );
+    }
+    wrapDBCalled = true;
     return { ...ctx, db: new DatabaseWriterWithTriggers(ctx, ctx.db, this) };
   };
 }
@@ -148,6 +157,7 @@ class Lock {
 let innerWriteLock = new Lock();
 let outerWriteLock = new Lock();
 const triggerQueue: (() => Promise<void>)[] = [];
+let wrapDBCalled = false;
 
 export class DatabaseWriterWithTriggers<
   DataModel extends GenericDataModel,