From 972d41037dce6a837dba82e7e9718b6f2710f4a4 Mon Sep 17 00:00:00 2001
From: KalleV <kvirtaneva@gmail.com>
Date: Tue, 22 Oct 2024 14:45:20 -0400
Subject: [PATCH] fix(html): avoid rendering [Object object] for undefined
 values

Signed-off-by: KalleV <kvirtaneva@gmail.com>
---
 lib/send-html.js      | 16 +++++++++++++---
 test/handler.test.mjs | 21 +++++++++++++++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/lib/send-html.js b/lib/send-html.js
index 02b2adb..fe615b2 100644
--- a/lib/send-html.js
+++ b/lib/send-html.js
@@ -16,6 +16,8 @@ const compiledTemplates = {
 
 module.exports = sendHtml;
 
+const STANDARD_PROPS = ['name', 'statusCode', 'message', 'stack'];
+
 /**
  * Sends HTML response to the client.
  *
@@ -24,7 +26,16 @@ module.exports = sendHtml;
  * @param {Object} options - The options object.
  */
 function sendHtml(res, data, options) {
-  const toRender = {options, data};
+  // Filter out properties with undefined / null values and keep standard properties
+  const filteredData = Object.keys(data).reduce((obj, key) => {
+    if (data[key] || STANDARD_PROPS.includes(key)) {
+      obj[key] = data[key];
+    }
+    return obj;
+  }, {});
+
+  const toRender = {options, data: filteredData};
+
   // TODO: ability to call non-default template functions from options
   const body = compiledTemplates.default(toRender);
   sendResponse(res, body);
@@ -50,8 +61,7 @@ handlebars.registerHelper('partial', partial);
  * @returns {string} - The result of the Handlebars template.
  */
 function standardProps(prop, options) {
-  const standardProps = ['name', 'statusCode', 'message', 'stack'];
-  if (standardProps.indexOf(prop) === -1) {
+  if (STANDARD_PROPS.indexOf(prop) === -1) {
     return options.fn(this);
   }
   return options.inverse(this);
diff --git a/test/handler.test.mjs b/test/handler.test.mjs
index d1b04f7..dc52349 100644
--- a/test/handler.test.mjs
+++ b/test/handler.test.mjs
@@ -683,6 +683,27 @@ describe('strong-error-handler', function() {
         });
     });
 
+    it('hides undefined properties from the HTML response', function(done) {
+      const error = new ErrorWithProps({
+        message: 'A test error message',
+        details: undefined,
+        code: undefined,
+      });
+      error.statusCode = 400;
+      givenErrorHandlerForError(error);
+      requestHTML()
+        .end(function(err, res) {
+          expect(res.statusCode).to.eql(400);
+
+          const body = res.error.text;
+
+          expect(body).to.match(/400(.*?)A test error message/);
+          expect(body).not.to.match(/details/);
+          expect(body).not.to.match(/code/);
+          done();
+        });
+    });
+
     function requestHTML(url) {
       return request.get(url || '/')
         .set('Accept', 'text/html')