Merge pull request frappe#36194 from AarDG10/fix-null-fallback-pg

fix(query): fix ifnull fallback in postgres

Author: akhilnarang

frappe/database/query.py

@@ -1607,6 +1607,24 @@ def _get_ifnull_fallback(self, doctype: str, fieldname: str) -> str:
 			meta = frappe.get_meta(doctype)
 			df = meta.get_field(fieldname)
 		except Exception:
+			if frappe.db.db_type == "postgres":
+				"""check type and accordingly choose fallback (to avoid postgres type cast errors)"""
+				target_table = frappe.utils.get_table_name(doctype)
+				info_schema = frappe.qb.Schema("information_schema")
+				columns = info_schema.columns
+				current_schema = frappe.conf.get("db_schema", "public")
+				res = (
+					frappe.qb.from_(columns)
+					.select(columns.data_type)
+					.where(
+						(columns.table_name == target_table)
+						& (columns.column_name == fieldname)
+						& (columns.table_schema == current_schema)
+					)
+				).run(pluck=True)
+				data_type = res[0] if res else None
+				if data_type in ("smallint", "bigint", "int", "numeric"):  # can add as needed
+					return "0"
 			return "''"
 
 		if df is None:

frappe/tests/test_query.py

@@ -2289,6 +2289,15 @@ def test_permission_query_conditions_with_filter(self):
 		# the filter should still apply and return no results
 		self.assertEqual(len(result), 0, "Filter should not be bypassed by shared doc OR condition")
 
+	@run_only_if(db_type_is.POSTGRES)
+	def test_ifnull_fallback_postgres(self):
+		"""Test ifnull fallback in postgres"""
+		from frappe.database.query import Engine
+
+		engine = Engine()
+		self.assertEqual(engine._get_ifnull_fallback("Patch Log", "skipped"), "0")
+		self.assertEqual(engine._get_ifnull_fallback("Patch Log", "patch"), "''")
+
 
 # This function is used as a permission query condition hook
 def test_permission_hook_condition(user):