fix: invlaid integer validations for biging

closes https://github.com/frappe/frappe/issues/25566

frappe/core/doctype/doctype/test_doctype.py

@@ -10,6 +10,7 @@ import frappe
 from frappe.cache_manager import clear_doctype_cache
 from frappe.core.doctype.doctype.doctype import (
 	CannotIndexedError,
+	DocType,
 	DoctypeLinkError,
 	HiddenAndMandatoryWithoutDefaultError,
 	IllegalMandatoryError,
@@ -782,7 +783,7 @@ def new_doctype(
 	custom: bool = True,
 	default: str | None = None,
 	**kwargs,
-):
+) -> "DocType":
 	if not name:
 		# Test prefix is required to avoid coverage
 		name = "Test " + "".join(random.sample(string.ascii_lowercase, 10))

frappe/model/base_document.py

@@ -983,6 +983,9 @@ class BaseDocument:
 					self.throw_length_exceeded_error(df, max_length, value)
 
 			elif column_type in ("int", "bigint", "smallint"):
+				if cint(df.get("length")) > 11:  # We implicitl switch to bigint for >11
+					column_type = "bigint"
+
 				max_length = max_positive_value[column_type]
 
 				if abs(cint(value)) > max_length:

frappe/tests/test_db_update.py

@@ -99,6 +99,16 @@ class TestDBUpdate(FrappeTestCase):
 			len(indexes), 1, msg=f"There should be 1 index on {doctype}.{field}, found {indexes}"
 		)
 
+	def test_bigint_conversion(self):
+		doctype = new_doctype(fields=[{"fieldname": "int_field", "fieldtype": "Int"}]).insert()
+
+		with self.assertRaises(frappe.CharacterLengthExceededError):
+			frappe.get_doc(doctype=doctype.name, int_field=2**62 - 1).insert()
+
+		doctype.fields[0].length = 14
+		doctype.save()
+		frappe.get_doc(doctype=doctype.name, int_field=2**62 - 1).insert()
+
 	@run_only_if(db_type_is.MARIADB)
 	def test_unique_index_on_install(self):
 		"""Only one unique index should be added"""