Handle null::text casts in postgresql dialect, fix panics

CHANGELOG_DEV.md

@@ -1,3 +1,6 @@
+## 0.92.0 - 2021-12-29
+- Improve sqlparser, support `null::text` type casts and avoid panics.
+
 ## 0.92.0 - 2021-12-22
 - Extend python examples, add mysql support
 - Generate certificates with service names as additional SAN for docker-compose files. Extend bash script to support several

sqlparser/ast.go

@@ -1221,21 +1221,32 @@ const (
 	ValArg
 	BitVal
 	PgEscapeString
-	Casted
 	PgPlaceholder
+	// Use this type for casted values that are different from SQLVal.
+	// because we have existing logic of comparison and formatting SQLVal
+	// and it easier to extend this one instead of propagating postgresql value conversion
+	// to all kinds of Expr. Maybe in a future when we will know more cases when it useful for
+	// our data manipulation, we will refactor it. Now it's just to support generic queries and avoid
+	// a lot of refactoring of sql.y and SQL grammar
+	UnknownVal
 )
 
 // SQLVal represents a single value.
 type SQLVal struct {
 	Type     ValType
 	Val      []byte
 	CastType []byte
+	unknown  Expr
 }
 
 // NewCastVal builds new CastVal
 func NewCastVal(val Expr, castType []byte) *SQLVal {
-	v := val.(*SQLVal)
-	return &SQLVal{Type: v.Type, Val: v.Val, CastType: castType}
+	switch v := val.(type) {
+	case *SQLVal:
+		return &SQLVal{Type: v.Type, Val: v.Val, CastType: castType}
+	default:
+		return &SQLVal{unknown: val, Type: UnknownVal, CastType: castType}
+	}
 }
 
 // ErrInvalidStringLiteralQuotes if used string token as literal with incorrect quotes

sqlparser/ast_methods.go

@@ -1339,6 +1339,8 @@ func (node *SQLVal) Format(buf *TrackedBuffer) {
 		buf.Myprintf("E'%s'", sqltypes.EncodeBytesSQLWithoutQuotes(node.Val))
 	case PgPlaceholder:
 		buf.Myprintf("%s", []byte(node.Val))
+	case UnknownVal:
+		node.unknown.Format(buf)
 	default:
 		panic("unexpected")
 	}

sqlparser/ast_test.go

@@ -679,3 +679,30 @@ func TestEmptyQuery(t *testing.T) {
 		}
 	}
 }
+
+func TestUnknownCastVal(t *testing.T) {
+	type testcase struct {
+		expr      Expr
+		castType  []byte
+		resultVal []byte
+	}
+	testcases := []testcase{
+		{
+			expr:      &NullVal{},
+			castType:  []byte(`::text`),
+			resultVal: nil,
+		},
+	}
+	for _, tcase := range testcases {
+		value := NewCastVal(tcase.expr, tcase.castType)
+		if value.unknown != tcase.expr {
+			t.Fatal("Unknown value != source expression")
+		}
+		if !bytes.Equal(value.Val, tcase.resultVal) {
+			t.Fatal("SQLVal.Val != expected value")
+		}
+		if !bytes.Equal(value.CastType, tcase.castType) {
+			t.Fatal("SQLVal.CastType != expected cast type")
+		}
+	}
+}

sqlparser/parse_test.go

@@ -1315,6 +1315,9 @@ var (
 	}, {
 		input:  "drop database if exists test_db",
 		output: "drop database test_db",
+	}, {
+		input:  "select NULL::text from dual",
+		output: "select null::text from dual",
 	}}
 )
 

tests/test.py

@@ -8762,15 +8762,6 @@ def test_invalid_specified_values(self):
         self.assertTrue(found, "Not found any expected exception")
 
 
-class TestPanicRecover(AcraCatchLogsMixin, BaseTestCase):
-    def testRecovering(self):
-        with self.assertRaises(DatabaseError):
-            # call unsupported query by sqlparser
-            self.engine1.execute('select null::text from dual;')
-
-        self.assertIn('panic in connection processing, close connection', self.read_log(self.acra).lower())
-
-
 class TestRegressionInvalidOctalEncoding(BaseTokenizationWithBinaryPostgreSQL):
     def testOctalIntegerValue(self):
         default_client_id_table = sa.Table(