From 82fcf1460ac80853a4b137a8209b5747ee114fc8 Mon Sep 17 00:00:00 2001
From: Lin Zhiwen <zhiwenlin1116@gmail.com>
Date: Wed, 11 Sep 2024 23:57:17 +0800
Subject: [PATCH] fix: fix update value containing "where" cause exception

---
 CHANGELOG.md                                |  9 +++++++
 clickhouse_backend/backend/introspection.py |  4 +--
 clickhouse_backend/driver/connection.py     | 27 ++++++++++++++-------
 tests/queries/tests.py                      |  7 ++++++
 4 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7fa743f..bb51381 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,12 @@
+### unreleased
+
+- fix: #99 fix update value containing "where" cause exception.
+
+### 1.3.0
+
+- fix: #93 last_executed_query() when params is a mapping of values.
+- feature: #95 upgrade dependencies.
+
 ### 1.2.0
 
 - feat: #72 support window functions.
diff --git a/clickhouse_backend/backend/introspection.py b/clickhouse_backend/backend/introspection.py
index 2f8d80c..d38d3fb 100644
--- a/clickhouse_backend/backend/introspection.py
+++ b/clickhouse_backend/backend/introspection.py
@@ -12,10 +12,10 @@
 TableInfo = namedtuple("TableInfo", BaseTableInfo._fields + ("comment",))
 
 constraint_pattern = re.compile(
-    r"CONSTRAINT (`)?((?(1)(?:[^\\`]|\\.)+|\S+))(?(1)`|) (CHECK .+?),?\n"
+    r"CONSTRAINT (`)?((?(1)(?:\\.|[^`])+|\S+))(?(1)`|) (CHECK .+?),?\n"
 )
 index_pattern = re.compile(
-    r"INDEX (`)?((?(1)(?:[^\\`]|\\.)+|\S+))(?(1)`|) (.+? TYPE ([a-zA-Z_][0-9a-zA-Z_]*)\(.+?\) GRANULARITY \d+)"
+    r"INDEX (`)?((?(1)(?:\\.|[^`])+|\S+))(?(1)`|) (.+? TYPE ([a-zA-Z_][0-9a-zA-Z_]*)\(.+?\) GRANULARITY \d+)"
 )
 
 
diff --git a/clickhouse_backend/driver/connection.py b/clickhouse_backend/driver/connection.py
index a825b4f..b7c3ee5 100644
--- a/clickhouse_backend/driver/connection.py
+++ b/clickhouse_backend/driver/connection.py
@@ -10,10 +10,10 @@
 from .escape import escape_params
 from .pool import ClickhousePool
 
-update_pattern = re.compile(
-    r"^\s*alter\s+table\s+(\S+)\s+.*?update.+?where\s+(.+?)(?:settings\s+.+)?$",
-    flags=re.IGNORECASE,
-)
+name_regex = r'"(?:[^"]|\\.)+"'
+value_regex = r"(')?(?(1)(?:[^']|\\.)+|\S+)(?(1)'|)"
+name_value_regex = f"{name_regex} = {value_regex}"
+update_pattern = re.compile(f"^ALTER TABLE ({name_regex}) UPDATE ")
 
 
 def send_query(self, query, query_id=None, params=None):
@@ -100,11 +100,20 @@ def execute(self, operation, parameters=None):
             query = self._client.substitute_params(
                 operation, parameters, self._client.connection.context
             )
-            table, where = update_pattern.match(query).groups()
-            super().execute(f"select count(*) from {table} where {where}")
-            (rowcount,) = self.fetchone()
-            self._reset_state()
-            self._rowcount = rowcount
+            m = update_pattern.match(query)
+            table = m.group(1)
+            query_upper = query.upper()
+            i = query_upper.rfind(" WHERE ")
+            if i > 0:
+                j = query_upper.rfind(" SETTINGS ", i + 7)
+                if j > 0:
+                    where = query[i + 7 : j]
+                else:
+                    where = query[i + 7 :]
+                super().execute(f"select count(*) from {table} where {where}")
+                (rowcount,) = self.fetchone()
+                self._reset_state()
+                self._rowcount = rowcount
         super().execute(operation, parameters)
 
 
diff --git a/tests/queries/tests.py b/tests/queries/tests.py
index de69cf7..aaed34b 100644
--- a/tests/queries/tests.py
+++ b/tests/queries/tests.py
@@ -20,3 +20,10 @@ def test_update(self):
                 self.a1.save()
             with self.assertRaises(models.Author.MultipleObjectsReturned):
                 self.a1.refresh_from_db()
+
+    # regression test for https://github.com/jayvynl/django-clickhouse-backend/issues/99
+    def test_update_special_string_val(self):
+        self.a1.name = "where **"
+        self.a1.save()
+        self.a1.refresh_from_db()
+        self.assertEqual(self.a1.name, "where **")