fix: improve stacktrace of errors generated by proxied Prisma methods

packages/runtime/src/enhancements/proxy.ts

@@ -155,6 +155,9 @@ export class DefaultPrismaProxyHandler implements PrismaProxyHandler {
     }
 }
 
+// a marker for filtering error stack trace
+const ERROR_MARKER = '__error_marker__';
+
 /**
  * Makes a Prisma client proxy.
  */
@@ -216,9 +219,71 @@ export function makeProxy<T extends PrismaProxyHandler>(
                 return undefined;
             }
 
-            return makeHandler(target, prop);
+            return createHandlerProxy(makeHandler(target, prop));
         },
     });
 
     return proxy;
 }
+
+// A proxy for capturing errors and processing stack trace
+function createHandlerProxy<T extends PrismaProxyHandler>(handler: T): T {
+    return new Proxy(handler, {
+        get(target, propKey) {
+            const prop = target[propKey as keyof T];
+            if (typeof prop !== 'function') {
+                return prop;
+            }
+
+            // eslint-disable-next-line @typescript-eslint/ban-types
+            const origMethod = prop as Function;
+            return async function (...args: any[]) {
+                const _err = new Error(ERROR_MARKER);
+                try {
+                    return await origMethod.apply(handler, args);
+                } catch (err) {
+                    if (_err.stack && err instanceof Error) {
+                        (err as any).internalStack = err.stack;
+                        err.stack = cleanCallStack(_err.stack, propKey.toString(), err.message);
+                    }
+                    throw err;
+                }
+            };
+        },
+    });
+}
+
+// Filter out @zenstackhq/runtime stack (generated by proxy) from stack trace
+function cleanCallStack(stack: string, method: string, message: string) {
+    // message line
+    let resultStack = `Error calling enhanced Prisma method \`${method}\`: ${message}`;
+
+    const lines = stack.split('\n');
+    let foundMarker = false;
+
+    for (let i = 0; i < lines.length; i++) {
+        const line = lines[i];
+
+        if (!foundMarker) {
+            // find marker, then stack trace lines follow
+            if (line.includes(ERROR_MARKER)) {
+                foundMarker = true;
+            }
+            continue;
+        }
+
+        // skip leading zenstack and anonymous lines
+        if (line.includes('@zenstackhq/runtime') || line.includes('<anonymous>')) {
+            continue;
+        }
+
+        // capture remaining lines
+        resultStack += lines
+            .slice(i)
+            .map((l) => '\n' + l)
+            .join();
+        break;
+    }
+
+    return resultStack;
+}

tests/integration/tests/misc/stacktrace.test.ts

@@ -0,0 +1,39 @@
+import { loadSchema } from '@zenstackhq/testtools';
+import path from 'path';
+
+describe('Stack trace tests', () => {
+    let origDir: string;
+
+    beforeAll(async () => {
+        origDir = path.resolve('.');
+    });
+
+    afterEach(() => {
+        process.chdir(origDir);
+    });
+
+    it('stack trace', async () => {
+        const { withPolicy } = await loadSchema(
+            `
+        model Model {
+            id String @id @default(uuid())
+        }
+        `
+        );
+
+        const db = withPolicy();
+        let error: Error | undefined = undefined;
+
+        try {
+            await db.model.create({ data: {} });
+        } catch (err) {
+            error = err as Error;
+        }
+
+        expect(error?.stack).toContain(
+            "Error calling enhanced Prisma method `create`: denied by policy: model entities failed 'create' check"
+        );
+        expect(error?.stack).toContain(`misc/stacktrace.test.ts`);
+        expect((error as any).internalStack).toBeTruthy();
+    });
+});