fix(firestore-send-email): make attachment validation more lenient and more robust

Author: cabljac

firestore-send-email/functions/__tests__/prepare-payload.test.ts

@@ -398,7 +398,7 @@ describe("preparePayload Template Merging", () => {
       await expect(preparePayload(payload)).rejects.toThrow();
     });
 
-    it("should handle null attachments", async () => {
+    it("should handle null attachments as no attachments", async () => {
       const payload = {
         to: "test@example.com",
         message: {
@@ -408,7 +408,24 @@ describe("preparePayload Template Merging", () => {
         },
       };
 
-      await expect(preparePayload(payload)).rejects.toThrow();
+      const result = await preparePayload(payload);
+      expect(result.message.attachments).toBeUndefined();
+    });
+
+    it("should normalize single attachment object to array", async () => {
+      const payload = {
+        to: "test@example.com",
+        message: {
+          subject: "Test Subject",
+          text: "Test text",
+          attachments: { filename: "test.txt", content: "test content" },
+        },
+      };
+
+      const result = await preparePayload(payload);
+      expect(result.message.attachments).toEqual([
+        { filename: "test.txt", content: "test content" },
+      ]);
     });
 
     it("should handle undefined attachments", async () => {

firestore-send-email/functions/__tests__/validation.test.ts

@@ -601,22 +601,16 @@ describe("validatePayload", () => {
         );
       });
 
-      it("should throw error for non-array attachments", () => {
-        const invalidPayload = {
+      it("should accept single attachment object and normalize to array", () => {
+        const payload = {
           to: "test@example.com",
           message: {
             subject: "Test Subject",
             text: "Test message",
-            attachments: {
-              filename: "test.txt",
-              content: "test",
-            },
+            attachments: { filename: "test.txt", content: "test" },
           },
         };
-        expect(() => validatePayload(invalidPayload)).toThrow(ValidationError);
-        expect(() => validatePayload(invalidPayload)).toThrow(
-          "Invalid message configuration: Field 'message.attachments' must be an array"
-        );
+        expect(() => validatePayload(payload)).not.toThrow();
       });
     });
   });

firestore-send-email/functions/src/prepare-payload.ts

@@ -3,6 +3,7 @@ import {
   validatePayload,
   attachmentSchema,
   attachmentsSchema,
+  ValidationError,
 } from "./validation";
 import * as logs from "./logs";
 import config from "./config";
@@ -41,11 +42,19 @@ export async function preparePayload(
     const templateRender = await templates.render(template.name, template.data);
     const mergeMessage = payload.message || {};
 
-    let attachments = attachmentsSchema.parse(
-      templateRender.attachments
-        ? templateRender.attachments
-        : mergeMessage.attachments
-    );
+    const attachmentsInput = templateRender.attachments
+      ? templateRender.attachments
+      : mergeMessage.attachments;
+
+    const attachmentsResult = attachmentsSchema.safeParse(attachmentsInput);
+    if (!attachmentsResult.success) {
+      throw new ValidationError(
+        `Invalid attachments: ${attachmentsResult.error.issues
+          .map((i) => i.message)
+          .join(", ")}`
+      );
+    }
+    let attachments = attachmentsResult.data;
 
     const handleTemplateValue = (value: any) => {
       if (value === null) {
@@ -75,6 +84,19 @@ export async function preparePayload(
     });
 
     payload.message = Object.assign(mergeMessage, templateContent);
+  } else if (payload.message?.attachments !== undefined) {
+    // Normalize attachments for non-template messages
+    const attachmentsResult = attachmentsSchema.safeParse(
+      payload.message.attachments
+    );
+    if (!attachmentsResult.success) {
+      throw new ValidationError(
+        `Invalid attachments: ${attachmentsResult.error.issues
+          .map((i) => i.message)
+          .join(", ")}`
+      );
+    }
+    payload.message.attachments = attachmentsResult.data;
   }
 
   let to: string[] = [];

firestore-send-email/functions/src/validation.ts

@@ -53,8 +53,19 @@ export const attachmentSchema = z
   });
 
 export const attachmentsSchema = z
-  .array(attachmentSchema)
-  .optional()
+  .preprocess(
+    // Normalize inputs before validation:
+    // - null/undefined → undefined (no attachments)
+    // - single object → wrap in array
+    // - array → pass through
+    (val) => {
+      if (val === undefined || val === null) return undefined;
+      if (Array.isArray(val)) return val;
+      if (typeof val === "object") return [val];
+      return val; // Let validation handle invalid types
+    },
+    z.array(attachmentSchema).optional()
+  )
   .transform((attachments) =>
     attachments
       ? attachments.filter((attachment) => Object.keys(attachment).length > 0)