From 33b970787a566af7acba31fe4563e17522211971 Mon Sep 17 00:00:00 2001
From: peterolkhov <peter@useprox.com>
Date: Wed, 11 Nov 2026 15:30:10 -0500
Subject: [PATCH] Fix stale selections when filling select controls

---
 fasthtml/components.py      |  2 ++
 nbs/api/01_components.ipynb | 69 +++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)

diff --git a/fasthtml/components.py b/fasthtml/components.py
index 9296fba3..9aa584cc 100644
--- a/fasthtml/components.py
+++ b/fasthtml/components.py
@@ -171,6 +171,8 @@ def _fill_item(item, obj):
             else: attr['value'] = val
         if tag=='textarea': cs=(val,)
         if tag == 'select':
+            for opt in cs:
+                if opt.tag == 'option': opt.attrs.pop('selected', None)
             if isinstance(val, list):
                 for opt in cs:
                     if opt.tag == 'option' and opt.get('value') in val:
diff --git a/nbs/api/01_components.ipynb b/nbs/api/01_components.ipynb
index 4e58cb22..2b0a42cc 100644
--- a/nbs/api/01_components.ipynb
+++ b/nbs/api/01_components.ipynb
@@ -1020,6 +1020,8 @@
     "            else: attr['value'] = val\n",
     "        if tag=='textarea': cs=(val,)\n",
     "        if tag == 'select':\n",
+    "            for opt in cs:\n",
+    "                if opt.tag == 'option': opt.attrs.pop('selected', None)\n",
     "            if isinstance(val, list):\n",
     "                for opt in cs:\n",
     "                    if opt.tag == 'option' and opt.get('value') in val:\n",
@@ -1128,6 +1130,73 @@
     "multiform"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "e75bc116",
+   "metadata": {},
+   "source": [
+    "Supplied select values replace existing selections, including defaults. An empty list clears them; missing or `None` values and controls with `skip` retain their selections."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "2fd0d42a",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def selected_values(form): return lx.fromstring(to_xml(form)).xpath('//option[@selected]/@value')\n",
+    "\n",
+    "test_eq(selected_values(multiform), ['a', 'c'])\n",
+    "multiform = fill_form(multiform, {'items': ['b']})\n",
+    "test_eq(selected_values(multiform), ['b'])\n",
+    "multiform = fill_form(multiform, {'items': []})\n",
+    "test_eq(selected_values(multiform), [])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "d815c231",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def default_select(**kw):\n",
+    "    return Form(Select(Option('a', value='a', selected=True, data_foo='bar'), Option('b', value='b'), name='items', **kw))\n",
+    "\n",
+    "for val,expected in [(['b'], ['b']), ([], []), ('b', ['b']), ('missing', [])]:\n",
+    "    filled = fill_form(default_select(multiple=True), {'items': val})\n",
+    "    test_eq(selected_values(filled), expected)\n",
+    "    test_eq(lx.fromstring(to_xml(filled)).xpath('//option[@value=\"a\"]/@data-foo'), ['bar'])\n",
+    "for obj in ({}, {'items': None}): test_eq(selected_values(fill_form(default_select(), obj)), ['a'])\n",
+    "test_eq(selected_values(fill_form(default_select(skip=True), {'items': ['b']})), ['a'])\n",
+    "\n",
+    "scalarform = Form(Select(Option('a', value='a', selected=True), Option('first b', value='b'),\n",
+    "                         Option('second b', value='b', selected=True), name='items'))\n",
+    "scalarform = fill_form(scalarform, {'items': 'b'})\n",
+    "test_eq(lx.fromstring(to_xml(scalarform)).xpath('//option[@selected]/text()'), ['first b'])\n",
+    "test_eq(selected_values(fill_form(scalarform, {'items': 'missing'})), [])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "3179b5ef",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "controls = Form(Input(type='checkbox', name='checks', value='a', checked=True),\n",
+    "                Input(type='checkbox', name='checks', value='b'),\n",
+    "                Input(type='radio', name='radio', value='a', checked=True), Input(type='radio', name='radio', value='b'),\n",
+    "                Input(name='title', value='old', data_foo='bar'), Textarea('old', name='details'))\n",
+    "controls = fill_form(controls, {'checks': ['b'], 'radio': 'b', 'title': 'new', 'details': 'new details'})\n",
+    "controls = lx.fromstring(to_xml(controls))\n",
+    "test_eq(controls.xpath('//input[@checked]/@value'), ['b', 'b'])\n",
+    "test_eq(controls.xpath('//input[@name=\"title\"]/@value'), ['new'])\n",
+    "test_eq(controls.xpath('//input[@name=\"title\"]/@data-foo'), ['bar'])\n",
+    "test_eq(controls.xpath('//textarea/text()'), ['new details'])"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,