From c725389123f3e8573c4d30ecf2f58cb6cbf2e610 Mon Sep 17 00:00:00 2001
From: jradtilbrook <jarryd@tilbrooktech.com>
Date: Fri, 8 May 2026 15:27:58 +0800
Subject: [PATCH] Fix false positive error detection when JSON data contains
 ClickHouse exception text

---
 src/Statement.php         | 10 +++++++++-
 tests/LargeStreamTest.php | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/Statement.php b/src/Statement.php
index bc55352..aa7af07 100644
--- a/src/Statement.php
+++ b/src/Statement.php
@@ -111,7 +111,15 @@ private function hasErrorClickhouse(string $body, ?string $contentType): bool {
 
         if (strlen($body) > 4096) {
             $tail = substr($body, -4096);
-            return preg_match(self::CLICKHOUSE_ERROR_REGEX, $tail) === 1;
+            if (preg_match(self::CLICKHOUSE_ERROR_REGEX, $tail) === 1) {
+                // Regex also matches if the actual data contains a ClickHouse error
+                // string. Use json_validate() to confirm the response is truly broken.
+                if (function_exists('json_validate')) {
+                    return !json_validate($body);
+                }
+                return true;
+            }
+            return false;
         }
 
         try {
diff --git a/tests/LargeStreamTest.php b/tests/LargeStreamTest.php
index 001bdae..3019381 100644
--- a/tests/LargeStreamTest.php
+++ b/tests/LargeStreamTest.php
@@ -65,6 +65,42 @@ public function testLargeBodyWithErrorAtEnd(): void
         $this->assertTrue($statement->isError());
     }
 
+    /**
+     * Large body with valid JSON containing ClickHouse error text as data.
+     */
+    public function testLargeJsonWithErrorPatternInDataIsNotError(): void
+    {
+        if (!function_exists('json_validate')) {
+            $this->markTestSkipped('json_validate() not available');
+        }
+
+        $rows = [];
+        for ($i = 0; $i < 100; $i++) {
+            $rows[] = '{"id":' . $i . ',"message":"Code: 60. DB::Exception: Table default.xxx doesn\'t exist. (UNKNOWN_TABLE) (version 24.3.2.23 (official build))"}';
+        }
+        $body = '{"meta":[{"name":"id","type":"UInt64"},{"name":"message","type":"String"}],'
+            . '"data":[' . implode(',', $rows) . '],'
+            . '"rows":100,'
+            . '"statistics":{"elapsed":0.001,"rows_read":100,"bytes_read":4096}}';
+
+        // Ensure body exceeds the 4096-byte threshold
+        $this->assertGreaterThan(4096, strlen($body));
+
+        $responseMock = $this->createMock(CurlerResponse::class);
+        $responseMock->method('http_code')->willReturn(200);
+        $responseMock->method('error_no')->willReturn(0);
+        $responseMock->method('content_type')->willReturn('application/json; charset=UTF-8');
+        $responseMock->method('body')->willReturn($body);
+
+        $requestMock = $this->createMock(CurlerRequest::class);
+        $requestMock->method('response')->willReturn($responseMock);
+        $requestMock->method('isResponseExists')->willReturn(true);
+
+        $statement = new Statement($requestMock);
+
+        $this->assertFalse($statement->isError());
+    }
+
     /**
      * Small body with valid JSON should still be checked for JSON validity.
      */