id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
37457	forms.JSONField raises an unhandled ValueError for JSON integers exceeding Python's digit limit	steinsgate		"Submitting a JSON integer exceeding Python's configured integer string conversion limit to forms.JSONField causes an unhandled ValueError instead of a field validation error.

Tested on Python 3.14.4 with the default limit of 4300 digits, using Django main at 36920bb4766679f5b32445797dcc5d32b8ff5ad2 (6.2 alpha), on Windows. No custom encoder or decoder is required.

=== Minimal reproduction ===

{{{#!python
import sys
from django.conf import settings
settings.configure(USE_I18N=False)
from django import forms

class PayloadForm(forms.Form):
    payload = forms.JSONField()

limit = sys.get_int_max_str_digits()
assert limit > 0
form = PayloadForm({""payload"": ""9"" * (limit + 1)})
form.is_valid()
}}}

Actual result:

{{{
ValueError: Exceeds the limit (4300 digits) for integer string conversion: value has 4301 digits; use sys.set_int_max_str_digits() to increase the limit
}}}

Expected result: is_valid() returns False, with the usual JSONField validation error (code ""invalid""). This report is about handling rejected input at the form boundary, not accepting arbitrary-length integers or disabling Python's conversion limit.

=== Related paths and controls ===

The same exception occurs with the integer inside a JSON array or object. It also escapes from forms.JSONField().clean(raw), the bound field value() method, and forms.JSONField().has_changed(None, raw). For bound input, the expected behavior is to preserve the submitted text for redisplay.

At the default limit, 4300-digit integers work; 4301-digit integers fail. Quoted digit strings and ordinary malformed JSON are handled normally. Adjusting the interpreter limit from 640 to 700 makes the same 641-digit input change from failure to success (the original limit was restored). IntegerField converts the equivalent conversion failure into ValidationError. A JSONDecoder using parse_int=str accepts the oversized numeric token, so any fix should preserve successful custom decoding.

=== Relation to #37418 ===

#37418, fixed by 9014ca5 / PR https://github.com/django/django/pull/22132, handled RecursionError for deeply nested JSON. JSONField.to_python() and bound_data() now catch JSONDecodeError and RecursionError, but json.loads() raises a plain ValueError for this integer conversion limit, which still escapes both handlers.

A regression test should cover clean(), bound-value redisplay, and form validation; has_changed() is another affected caller of to_python(). Broadening the decoding exception handlers to handle ValueError appears worth considering, including the behavior of custom decoders.

The problem was reproduced through form/field APIs without a database. Other Django release branches and an HTTP/admin integration were not tested. No patch is attached.

AI assistance disclosure: OpenAI Codex assisted with investigation, reproduction scripts, and preparation of this report.
"	Bug	new	Forms	dev	Normal				Unreviewed	0	0	0	0	0	0