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Respect htmx 4's HX-Request-Type: full header #948

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Respect htmx 4's HX-Request-Type: full header #948

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07956e0
Handle htmx 4 full-page requests
scriptogre Oct 29, 2026
128580b
Cover htmx 4 partial requests
scriptogre Oct 29, 2026
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6 changes: 3 additions & 3 deletions fasthtml/core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ class Cards: ... # class route group: each verb-named method (get, patch, .
A('More', href=foo.to(a=1)) # <a href="/foo?a=1"> `.to()` fills path params; the rest become query params.
Div('...', hx_get=foo) # route functions work directly as htmx attr values: hx-get="/foo"

Handlers return FT trees (from `fastcore.xml`), rendered as HTML automatically: a full page for regular requests, a bare fragment for HTMX requests. In a full page, top-level `Title`, `Meta`, `Link`, and `Style` items go in `<head>`; the rest goes in `<body>`. Strings are sent as HTML, dicts as JSON, and a Starlette `Response` is sent untouched. A return tuple may mix content with special items: any `HttpHeader` (e.g. from `cookie()` or `HtmxResponseHeaders()`) becomes a response header, any `BackgroundTask` runs after the response is sent, and the rest renders as content. `Redirect` picks the right redirect mechanism for HTMX vs regular requests, and `FtResponse` wraps FT content when you need the status code or headers.
Handlers return FT trees (from `fastcore.xml`), rendered as HTML automatically: a full page for regular requests and htmx 4 `full` requests, a bare fragment for other HTMX requests. In a full page, top-level `Title`, `Meta`, `Link`, and `Style` items go in `<head>`; the rest goes in `<body>`. Strings are sent as HTML, dicts as JSON, and a Starlette `Response` is sent untouched. A return tuple may mix content with special items: any `HttpHeader` (e.g. from `cookie()` or `HtmxResponseHeaders()`) becomes a response header, any `BackgroundTask` runs after the response is sent, and the rest renders as content. `Redirect` picks the right redirect mechanism for HTMX vs regular requests, and `FtResponse` wraps FT content when you need the status code or headers.

Handler parameters are filled from the request: each is looked up in path, cookie, header (snake_case names match Hyphen-Case headers), query, then form data, and cast by calling its annotation on the value. Hyphens in form/query names match underscores in handler parameters and typed body fields. Exact names take precedence within each source. Dictionary and request access retain the original keys. `bool`, `int`, and `date` get smart string parsing; `UploadFile` passes through. Repeated params take the last value unless annotated `list[T]`, which collects them all. A param with no annotation and no special name is ignored, with a warning. A dataclass, TypedDict, namedtuple, or any annotated class collects the whole form body; a `__from_request__` classmethod customizes construction. A missing required param is a 400, a failed cast a 404. These special names need no annotation:

Expand Down Expand Up @@ -482,7 +482,7 @@ def respond(req, heads, bdy):
def is_full_page(req, resp):
"Check if response should be rendered as full page or fragment"
if resp and any(getattr(o, 'tag', '')=='html' for o in resp): return True
return 'hx-request' in req.headers and 'hx-history-restore-request' not in req.headers
return 'hx-request' in req.headers and req.headers.get('hx-request-type') != 'full' and 'hx-history-restore-request' not in req.headers

# %% ../nbs/api/00_core.ipynb #358badec
def _part_resp(req, resp):
Expand All @@ -491,7 +491,7 @@ def _part_resp(req, resp):
resp = resp + tuple(getattr(req, 'injects', ()))
http_hdrs,resp = partition(resp, risinstance(HttpHeader))
tasks,resp = partition(resp, risinstance(BackgroundTask))
kw = {"headers": {"vary": "HX-Request, HX-History-Restore-Request"}}
kw = {"headers": {"vary": "HX-Request, HX-Request-Type, HX-History-Restore-Request"}}
if http_hdrs: kw['headers'] |= {o.k:str(o.v) for o in http_hdrs}
if tasks:
ts = BackgroundTasks()
Expand Down
13 changes: 8 additions & 5 deletions nbs/api/00_core.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@
" A('More', href=foo.to(a=1)) # <a href=\"/foo?a=1\"> `.to()` fills path params; the rest become query params.\n",
" Div('...', hx_get=foo) # route functions work directly as htmx attr values: hx-get=\"/foo\"\n",
"\n",
"Handlers return FT trees (from `fastcore.xml`), rendered as HTML automatically: a full page for regular requests, a bare fragment for HTMX requests. In a full page, top-level `Title`, `Meta`, `Link`, and `Style` items go in `<head>`; the rest goes in `<body>`. Strings are sent as HTML, dicts as JSON, and a Starlette `Response` is sent untouched. A return tuple may mix content with special items: any `HttpHeader` (e.g. from `cookie()` or `HtmxResponseHeaders()`) becomes a response header, any `BackgroundTask` runs after the response is sent, and the rest renders as content. `Redirect` picks the right redirect mechanism for HTMX vs regular requests, and `FtResponse` wraps FT content when you need the status code or headers.\n",
"Handlers return FT trees (from `fastcore.xml`), rendered as HTML automatically: a full page for regular requests and htmx 4 `full` requests, a bare fragment for other HTMX requests. In a full page, top-level `Title`, `Meta`, `Link`, and `Style` items go in `<head>`; the rest goes in `<body>`. Strings are sent as HTML, dicts as JSON, and a Starlette `Response` is sent untouched. A return tuple may mix content with special items: any `HttpHeader` (e.g. from `cookie()` or `HtmxResponseHeaders()`) becomes a response header, any `BackgroundTask` runs after the response is sent, and the rest renders as content. `Redirect` picks the right redirect mechanism for HTMX vs regular requests, and `FtResponse` wraps FT content when you need the status code or headers.\n",
"\n",
"Handler parameters are filled from the request: each is looked up in path, cookie, header (snake_case names match Hyphen-Case headers), query, then form data, and cast by calling its annotation on the value. Hyphens in form/query names match underscores in handler parameters and typed body fields. Exact names take precedence within each source. Dictionary and request access retain the original keys. `bool`, `int`, and `date` get smart string parsing; `UploadFile` passes through. Repeated params take the last value unless annotated `list[T]`, which collects them all. A param with no annotation and no special name is ignored, with a warning. A dataclass, TypedDict, namedtuple, or any annotated class collects the whole form body; a `__from_request__` classmethod customizes construction. A missing required param is a 400, a failed cast a 404. These special names need no annotation:\n",
"\n",
Expand Down Expand Up @@ -1555,8 +1555,8 @@
"id": "cfae0a56",
"metadata": {},
"source": [
"Render fragment if `HX-Request` header is _present_ and\n",
" `HX-History-Restore-Request` header is _absent._"
"Render a fragment if `HX-Request` is present, `HX-Request-Type` is not `full`,\n",
"and `HX-History-Restore-Request` is absent."
]
},
{
Expand All @@ -1570,7 +1570,7 @@
"def is_full_page(req, resp):\n",
" \"Check if response should be rendered as full page or fragment\"\n",
" if resp and any(getattr(o, 'tag', '')=='html' for o in resp): return True\n",
" return 'hx-request' in req.headers and 'hx-history-restore-request' not in req.headers"
" return 'hx-request' in req.headers and req.headers.get('hx-request-type') != 'full' and 'hx-history-restore-request' not in req.headers"
]
},
{
Expand All @@ -1587,7 +1587,7 @@
" resp = resp + tuple(getattr(req, 'injects', ()))\n",
" http_hdrs,resp = partition(resp, risinstance(HttpHeader))\n",
" tasks,resp = partition(resp, risinstance(BackgroundTask))\n",
" kw = {\"headers\": {\"vary\": \"HX-Request, HX-History-Restore-Request\"}}\n",
" kw = {\"headers\": {\"vary\": \"HX-Request, HX-Request-Type, HX-History-Restore-Request\"}}\n",
" if http_hdrs: kw['headers'] |= {o.k:str(o.v) for o in http_hdrs}\n",
" if tasks:\n",
" ts = BackgroundTasks()\n",
Expand Down Expand Up @@ -3133,6 +3133,9 @@
"assert '<title>FastHTML page</title>' in txt and '<h1>bar</h1>' in txt and '<html>' in txt\n",
"\n",
"assert cli.get('/xt2', **hxhdr).text.strip() == '<h1>bar</h1>'\n",
"assert cli.get('/xt2', headers={'hx-request':\"1\", 'hx-request-type':\"partial\"}).text.strip() == '<h1>bar</h1>'\n",
"r = cli.get('/xt2', headers={'hx-request':\"1\", 'hx-request-type':\"full\"})\n",
"assert '<html>' in r.text and 'HX-Request-Type' in r.headers['vary']\n",
"\n",
"@rt('/xt3')\n",
"def get(): return Html(Head(Title('hi')), Body(P('there')))\n",
Expand Down
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