Add connection option for recursive triggers

Similar to foreign keys, the recursive triggers PRAGMA affects the
interpretation of all statements on a connection.

sqlite3.go

@@ -599,6 +599,8 @@ func errorString(err Error) string {
 //     "deferred", "exclusive".
 //   _foreign_keys=X
 //     Enable or disable enforcement of foreign keys.  X can be 1 or 0.
+//   _recursive_triggers=X
+//     Enable or disable recursive triggers.  X can be 1 or 0.
 func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	if C.sqlite3_threadsafe() == 0 {
 		return nil, errors.New("sqlite library was not compiled for thread-safe operation")
@@ -608,6 +610,7 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 	txlock := "BEGIN"
 	busyTimeout := 5000
 	foreignKeys := -1
+	recursiveTriggers := -1
 	pos := strings.IndexRune(dsn, '?')
 	if pos >= 1 {
 		params, err := url.ParseQuery(dsn[pos+1:])
@@ -662,6 +665,18 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 			}
 		}
 
+		// _recursive_triggers
+		if val := params.Get("_recursive_triggers"); val != "" {
+			switch val {
+			case "1":
+				recursiveTriggers = 1
+			case "0":
+				recursiveTriggers = 0
+			default:
+				return nil, fmt.Errorf("Invalid _recursive_triggers: %v", val)
+			}
+		}
+
 		if !strings.HasPrefix(dsn, "file:") {
 			dsn = dsn[:pos]
 		}
@@ -708,6 +723,17 @@ func (d *SQLiteDriver) Open(dsn string) (driver.Conn, error) {
 			return nil, err
 		}
 	}
+	if recursiveTriggers == 0 {
+		if err := exec("PRAGMA recursive_triggers = OFF;"); err != nil {
+			C.sqlite3_close_v2(db)
+			return nil, err
+		}
+	} else if recursiveTriggers == 1 {
+		if err := exec("PRAGMA recursive_triggers = ON;"); err != nil {
+			C.sqlite3_close_v2(db)
+			return nil, err
+		}
+	}
 
 	conn := &SQLiteConn{db: db, loc: loc, txlock: txlock}
 

sqlite3_test.go

@@ -136,6 +136,35 @@ func TestForeignKeys(t *testing.T) {
 	}
 }
 
+func TestRecursiveTriggers(t *testing.T) {
+	cases := map[string]bool{
+		"?_recursive_triggers=1": true,
+		"?_recursive_triggers=0": false,
+	}
+	for option, want := range cases {
+		fname := TempFilename(t)
+		uri := "file:" + fname + option
+		db, err := sql.Open("sqlite3", uri)
+		if err != nil {
+			os.Remove(fname)
+			t.Errorf("sql.Open(\"sqlite3\", %q): %v", uri, err)
+			continue
+		}
+		var enabled bool
+		err = db.QueryRow("PRAGMA recursive_triggers;").Scan(&enabled)
+		db.Close()
+		os.Remove(fname)
+		if err != nil {
+			t.Errorf("query recursive_triggers for %s: %v", uri, err)
+			continue
+		}
+		if enabled != want {
+			t.Errorf("\"PRAGMA recursive_triggers;\" for %q = %t; want %t", uri, enabled, want)
+			continue
+		}
+	}
+}
+
 func TestClose(t *testing.T) {
 	tempFilename := TempFilename(t)
 	defer os.Remove(tempFilename)