Never return char variants when reading prepared MySQL statements

This has undesired effects when converting a QSqlRecord to JSON.
A char(0) e.g. has special semantics that are undesired when
reading a Tinyint column.

I don't think that returning bool for the special case of a
Tinyint(1) is required. This also did not happen before, and
is also not happening when not using a prepared statement.
Instead, a plain int/uint QVariant is returned.

This patch extends tst_QSqlQuery::integralTypesMysql to also
cover reading and writing booleans from/to a MySQL table column
of type Tinyint(1). Additionally, the reading is now also done
with a prepared statement and we also check the raw variant
value.

The broken behavior fixed by this patch was introduced by me in
commit 194403a3483b7317cc9511bc8b2ab307775643c5.

Change-Id: I028a3abd83fdd2b42d98d478950d205e5b6bbeb5
Task-number: QTBUG-53397
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 9 insertions, 2 deletions

diff --git a/src/sql/drivers/mysql/qsql_mysql.cpp b/src/sql/drivers/mysql/qsql_mysql.cpp
index 99472542bf..c26c03ad07 100644
--- a/src/sql/drivers/mysql/qsql_mysql.cpp
+++ b/src/sql/drivers/mysql/qsql_mysql.cpp
@@ -596,8 +596,15 @@ QVariant QMYSQLResult::data(int field)
         if (f.nullIndicator)
             return QVariant(f.type);
 
-        if (qIsInteger(f.type))
-            return QVariant(f.type, f.outField);
+        if (qIsInteger(f.type)) {
+            QVariant variant(f.type, f.outField);
+            // we never want to return char variants here, see QTBUG-53397
+            if (static_cast<int>(f.type) == QMetaType::UChar)
+                return variant.toUInt();
+            else if (static_cast<int>(f.type) == QMetaType::Char)
+                return variant.toInt();
+            return variant;
+        }
 
         if (f.type != QVariant::ByteArray)
             val = toUnicode(d->driver->d_func()->tc, f.outField, f.bufLength);