fix(stripe): getCustomerCreateParams not actually being called (#5019)

Co-authored-by: Alex Yang <himself65@outlook.com>

packages/stripe/package.json

@@ -43,6 +43,7 @@
     }
   },
   "dependencies": {
+    "defu": "^6.1.4",
     "zod": "^4.1.5"
   },
   "peerDependencies": {

packages/stripe/src/index.ts

@@ -26,6 +26,7 @@ import type {
 } from "./types";
 import { getPlanByName, getPlanByPriceInfo, getPlans } from "./utils";
 import { getSchema } from "./schema";
+import { defu } from "defu";
 
 const STRIPE_ERROR_CODES = {
 	SUBSCRIPTION_NOT_FOUND: "Subscription not found",
@@ -1299,13 +1300,27 @@ export const stripe = <O extends StripeOptions>(options: O) => {
 							create: {
 								async after(user, ctx) {
 									if (ctx && options.createCustomerOnSignUp) {
-										const stripeCustomer = await client.customers.create({
+										let extraCreateParams: Partial<Stripe.CustomerCreateParams> =
+											{};
+										if (options.getCustomerCreateParams) {
+											extraCreateParams = await options.getCustomerCreateParams(
+												user,
+												ctx,
+											);
+										}
+
+										const params: Stripe.CustomerCreateParams = defu(
+											{
 												email: user.email,
 												name: user.name,
 												metadata: {
 													userId: user.id,
 												},
-										});
+											},
+											extraCreateParams,
+										);
+										const stripeCustomer =
+											await client.customers.create(params);
 										await ctx.context.internalAdapter.updateUser(user.id, {
 											stripeCustomerId: stripeCustomer.id,
 										});

packages/stripe/src/stripe.test.ts

@@ -1496,4 +1496,247 @@ describe("stripe", async () => {
 			email: "newemail@example.com",
 		});
 	});
+
+	describe("getCustomerCreateParams", () => {
+		it("should call getCustomerCreateParams and merge with default params", async () => {
+			const getCustomerCreateParamsMock = vi
+				.fn()
+				.mockResolvedValue({ metadata: { customField: "customValue" } });
+
+			const testOptions = {
+				...stripeOptions,
+				createCustomerOnSignUp: true,
+				getCustomerCreateParams: getCustomerCreateParamsMock,
+			} satisfies StripeOptions;
+
+			const testAuth = betterAuth({
+				database: memory,
+				baseURL: "http://localhost:3000",
+				emailAndPassword: {
+					enabled: true,
+				},
+				plugins: [stripe(testOptions)],
+			});
+
+			const testAuthClient = createAuthClient({
+				baseURL: "http://localhost:3000",
+				plugins: [bearer(), stripeClient({ subscription: true })],
+				fetchOptions: {
+					customFetchImpl: async (url, init) =>
+						testAuth.handler(new Request(url, init)),
+				},
+			});
+
+			// Sign up a user
+			const userRes = await testAuthClient.signUp.email(
+				{
+					email: "custom-params@email.com",
+					password: "password",
+					name: "Custom User",
+				},
+				{
+					throw: true,
+				},
+			);
+
+			// Verify getCustomerCreateParams was called
+			expect(getCustomerCreateParamsMock).toHaveBeenCalledWith(
+				expect.objectContaining({
+					id: userRes.user.id,
+					email: "custom-params@email.com",
+					name: "Custom User",
+				}),
+				expect.objectContaining({
+					context: expect.any(Object),
+				}),
+			);
+
+			// Verify customer was created with merged params
+			expect(mockStripe.customers.create).toHaveBeenCalledWith(
+				expect.objectContaining({
+					email: "custom-params@email.com",
+					name: "Custom User",
+					metadata: expect.objectContaining({
+						userId: userRes.user.id,
+						customField: "customValue",
+					}),
+				}),
+			);
+		});
+
+		it("should use getCustomerCreateParams to add custom address", async () => {
+			const getCustomerCreateParamsMock = vi.fn().mockResolvedValue({
+				address: {
+					line1: "123 Main St",
+					city: "San Francisco",
+					state: "CA",
+					postal_code: "94111",
+					country: "US",
+				},
+			});
+
+			const testOptions = {
+				...stripeOptions,
+				createCustomerOnSignUp: true,
+				getCustomerCreateParams: getCustomerCreateParamsMock,
+			} satisfies StripeOptions;
+
+			const testAuth = betterAuth({
+				database: memory,
+				baseURL: "http://localhost:3000",
+				emailAndPassword: {
+					enabled: true,
+				},
+				plugins: [stripe(testOptions)],
+			});
+
+			const testAuthClient = createAuthClient({
+				baseURL: "http://localhost:3000",
+				plugins: [bearer(), stripeClient({ subscription: true })],
+				fetchOptions: {
+					customFetchImpl: async (url, init) =>
+						testAuth.handler(new Request(url, init)),
+				},
+			});
+
+			// Sign up a user
+			await testAuthClient.signUp.email(
+				{
+					email: "address-user@email.com",
+					password: "password",
+					name: "Address User",
+				},
+				{
+					throw: true,
+				},
+			);
+
+			// Verify customer was created with address
+			expect(mockStripe.customers.create).toHaveBeenCalledWith(
+				expect.objectContaining({
+					email: "address-user@email.com",
+					name: "Address User",
+					address: {
+						line1: "123 Main St",
+						city: "San Francisco",
+						state: "CA",
+						postal_code: "94111",
+						country: "US",
+					},
+					metadata: expect.objectContaining({
+						userId: expect.any(String),
+					}),
+				}),
+			);
+		});
+
+		it("should properly merge nested objects using defu", async () => {
+			const getCustomerCreateParamsMock = vi.fn().mockResolvedValue({
+				metadata: {
+					customField: "customValue",
+					anotherField: "anotherValue",
+				},
+				phone: "+1234567890",
+			});
+
+			const testOptions = {
+				...stripeOptions,
+				createCustomerOnSignUp: true,
+				getCustomerCreateParams: getCustomerCreateParamsMock,
+			} satisfies StripeOptions;
+
+			const testAuth = betterAuth({
+				database: memory,
+				baseURL: "http://localhost:3000",
+				emailAndPassword: {
+					enabled: true,
+				},
+				plugins: [stripe(testOptions)],
+			});
+
+			const testAuthClient = createAuthClient({
+				baseURL: "http://localhost:3000",
+				plugins: [bearer(), stripeClient({ subscription: true })],
+				fetchOptions: {
+					customFetchImpl: async (url, init) =>
+						testAuth.handler(new Request(url, init)),
+				},
+			});
+
+			// Sign up a user
+			const userRes = await testAuthClient.signUp.email(
+				{
+					email: "merge-test@email.com",
+					password: "password",
+					name: "Merge User",
+				},
+				{
+					throw: true,
+				},
+			);
+
+			// Verify customer was created with properly merged params
+			// defu merges objects and preserves all fields
+			expect(mockStripe.customers.create).toHaveBeenCalledWith(
+				expect.objectContaining({
+					email: "merge-test@email.com",
+					name: "Merge User",
+					phone: "+1234567890",
+					metadata: {
+						userId: userRes.user.id,
+						customField: "customValue",
+						anotherField: "anotherValue",
+					},
+				}),
+			);
+		});
+
+		it("should work without getCustomerCreateParams", async () => {
+			// This test ensures backward compatibility
+			const testOptions = {
+				...stripeOptions,
+				createCustomerOnSignUp: true,
+				// No getCustomerCreateParams provided
+			} satisfies StripeOptions;
+
+			const testAuth = betterAuth({
+				database: memory,
+				baseURL: "http://localhost:3000",
+				emailAndPassword: {
+					enabled: true,
+				},
+				plugins: [stripe(testOptions)],
+			});
+
+			const testAuthClient = createAuthClient({
+				baseURL: "http://localhost:3000",
+				plugins: [bearer(), stripeClient({ subscription: true })],
+				fetchOptions: {
+					customFetchImpl: async (url, init) =>
+						testAuth.handler(new Request(url, init)),
+				},
+			});
+
+			// Sign up a user
+			const userRes = await testAuthClient.signUp.email(
+				{
+					email: "no-custom-params@email.com",
+					password: "password",
+					name: "Default User",
+				},
+				{
+					throw: true,
+				},
+			);
+
+			// Verify customer was created with default params only
+			expect(mockStripe.customers.create).toHaveBeenCalledWith({
+				email: "no-custom-params@email.com",
+				name: "Default User",
+				metadata: {
+					userId: userRes.user.id,
+				},
+			});
+		});
+	});
 });

packages/stripe/src/types.ts

@@ -199,12 +199,9 @@ export interface StripeOptions {
 	 * @returns
 	 */
 	getCustomerCreateParams?: (
-		data: {
+		user: User,
-			user: User;
-			session: Session;
-		},
 		ctx: GenericEndpointContext,
-	) => Promise<{}>;
+	) => Promise<Partial<Stripe.CustomerCreateParams>>;
 	/**
 	 * Subscriptions
 	 */

pnpm-lock.yaml

@@ -1154,6 +1154,9 @@ importers:
 
   packages/stripe:
     dependencies:
+      defu:
+        specifier: ^6.1.4
+        version: 6.1.4
       zod:
         specifier: ^4.1.5
         version: 4.1.5
@@ -14935,7 +14938,7 @@ snapshots:
       postcss: 8.4.49
       resolve-from: 5.0.0
     optionalDependencies:
-      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.81.4(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@react-native/metro-config@0.81.0(@babel/core@7.28.4))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
+      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.80.2(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
     transitivePeerDependencies:
       - bufferutil
       - supports-color
@@ -15020,7 +15023,7 @@ snapshots:
       '@expo/json-file': 10.0.7
       '@react-native/normalize-colors': 0.81.4
       debug: 4.4.1
-      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.81.4(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@react-native/metro-config@0.81.0(@babel/core@7.28.4))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
+      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.80.2(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
       resolve-from: 5.0.0
       semver: 7.7.2
       xml2js: 0.6.0
@@ -19179,7 +19182,7 @@ snapshots:
       resolve-from: 5.0.0
     optionalDependencies:
       '@babel/runtime': 7.28.4
-      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.81.4(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@react-native/metro-config@0.81.0(@babel/core@7.28.4))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
+      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.80.2(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
     transitivePeerDependencies:
       - '@babel/core'
       - supports-color
@@ -20741,7 +20744,7 @@ snapshots:
 
   expo-keep-awake@15.0.7(expo@54.0.10)(react@19.1.1):
     dependencies:
-      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.81.4(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@react-native/metro-config@0.81.0(@babel/core@7.28.4))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
+      expo: 54.0.10(@babel/core@7.28.4)(@expo/metro-runtime@6.1.2)(expo-router@6.0.8)(graphql@16.11.0)(react-native@0.80.2(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1)
       react: 19.1.1
 
   expo-linking@7.1.7(expo@54.0.10)(react-native@0.80.2(@babel/core@7.28.4)(@react-native-community/cli@20.0.1(typescript@5.9.2))(@types/react@19.1.12)(react@19.1.1))(react@19.1.1):