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QODBC: fix handling NULL values for strings

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Qt6 added a slight behavior change in QVariant - an empty QString in a
QVariant no longer results in QVariant::isNull(). This created an issue
that qGetStringData() could no longer return a NULL value. On the other
side, NULL values in Qt5 could not be distinguished to an empty string
which we now can.

Fixes: QTBUG-106607
Change-Id: Iddc6f7e8b97f5abc136bbbfd02d175b80152ac90
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 44ac742f730a5e8cac229067429eb2f5cb90105a)
This commit is contained in:
Christian Ehrlicher 2022-09-26 19:58:27 +02:00 committed by Volker Hilsheimer
parent 6b5eac4697
commit 7d452d17a4
1 changed files with 11 additions and 16 deletions
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27
src/plugins/sqldrivers/odbc/qsql_odbc.cpp
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@ -370,7 +370,7 @@ static QMetaType qDecodeODBCType(SQLSMALLINT sqltype, bool isSigned = true)
return QMetaType(type); return QMetaType(type);
} }
static QString qGetStringData(SQLHANDLE hStmt, int column, int colSize, bool unicode = false) static QVariant qGetStringData(SQLHANDLE hStmt, int column, int colSize, bool unicode)
{ {
QString fieldVal; QString fieldVal;
SQLRETURN r = SQL_ERROR; SQLRETURN r = SQL_ERROR;
@ -404,8 +404,7 @@ static QString qGetStringData(SQLHANDLE hStmt, int column, int colSize, bool uni
&lengthIndicator); &lengthIndicator);
if (r == SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO) { if (r == SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO) {
if (lengthIndicator == SQL_NULL_DATA) { if (lengthIndicator == SQL_NULL_DATA) {
fieldVal.clear(); return {};
break;
} }
// starting with ODBC Native Client 2012, SQL_NO_TOTAL is returned // starting with ODBC Native Client 2012, SQL_NO_TOTAL is returned
// instead of the length (which sometimes was wrong in older versions) // instead of the length (which sometimes was wrong in older versions)
@ -431,8 +430,7 @@ static QString qGetStringData(SQLHANDLE hStmt, int column, int colSize, bool uni
break; break;
} else { } else {
qWarning() << "qGetStringData: Error while fetching data (" << qWarnODBCHandle(SQL_HANDLE_STMT, hStmt) << ')'; qWarning() << "qGetStringData: Error while fetching data (" << qWarnODBCHandle(SQL_HANDLE_STMT, hStmt) << ')';
fieldVal.clear(); return {};
break;
} }
} }
} else { } else {
@ -454,8 +452,7 @@ static QString qGetStringData(SQLHANDLE hStmt, int column, int colSize, bool uni
&lengthIndicator); &lengthIndicator);
if (r == SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO) { if (r == SQL_SUCCESS || r == SQL_SUCCESS_WITH_INFO) {
if (lengthIndicator == SQL_NULL_DATA || lengthIndicator == SQL_NO_TOTAL) { if (lengthIndicator == SQL_NULL_DATA || lengthIndicator == SQL_NO_TOTAL) {
fieldVal.clear(); return {};
break;
} }
// if SQL_SUCCESS_WITH_INFO is returned, indicating that // if SQL_SUCCESS_WITH_INFO is returned, indicating that
// more data can be fetched, the length indicator does NOT // more data can be fetched, the length indicator does NOT
@ -475,8 +472,7 @@ static QString qGetStringData(SQLHANDLE hStmt, int column, int colSize, bool uni
break; break;
} else { } else {
qWarning() << "qGetStringData: Error while fetching data (" << qWarnODBCHandle(SQL_HANDLE_STMT, hStmt) << ')'; qWarning() << "qGetStringData: Error while fetching data (" << qWarnODBCHandle(SQL_HANDLE_STMT, hStmt) << ')';
fieldVal.clear(); return {};
break;
} }
} }
} }
@ -620,7 +616,7 @@ static QSqlField qMakeFieldInfo(const SQLHANDLE hStmt, int i, QString *errorMess
// by SQLColumns. The hStmt has to point to a valid position. // by SQLColumns. The hStmt has to point to a valid position.
static QSqlField qMakeFieldInfo(const SQLHANDLE hStmt, const QODBCDriverPrivate* p) static QSqlField qMakeFieldInfo(const SQLHANDLE hStmt, const QODBCDriverPrivate* p)
{ {
QString fname = qGetStringData(hStmt, 3, -1, p->unicode); QString fname = qGetStringData(hStmt, 3, -1, p->unicode).toString();
int type = qGetIntData(hStmt, 4).toInt(); // column type int type = qGetIntData(hStmt, 4).toInt(); // column type
QSqlField f(fname, qDecodeODBCType(type, p)); QSqlField f(fname, qDecodeODBCType(type, p));
QVariant var = qGetIntData(hStmt, 6); QVariant var = qGetIntData(hStmt, 6);
@ -1261,7 +1257,7 @@ QVariant QODBCResult::data(int field)
} }
break; break;
default: default:
d->fieldCache[i] = QVariant(qGetStringData(d->hStmt, i, info.length(), false)); d->fieldCache[i] = qGetStringData(d->hStmt, i, info.length(), false);
break; break;
} }
d->fieldCacheIdx = field + 1; d->fieldCacheIdx = field + 1;
@ -2392,8 +2388,7 @@ QStringList QODBCDriver::tables(QSql::TableType type) const
} }
while (r == SQL_SUCCESS) { while (r == SQL_SUCCESS) {
QString fieldVal = qGetStringData(hStmt, 2, -1, d->unicode); tl.append(qGetStringData(hStmt, 2, -1, d->unicode).toString());
tl.append(fieldVal);
if (d->hasSQLFetchScroll) if (d->hasSQLFetchScroll)
r = SQLFetchScroll(hStmt, r = SQLFetchScroll(hStmt,
@ -2490,11 +2485,11 @@ QSqlIndex QODBCDriver::primaryIndex(const QString& tablename) const
// Store all fields in a StringList because some drivers can't detail fields in this FETCH loop // Store all fields in a StringList because some drivers can't detail fields in this FETCH loop
while (r == SQL_SUCCESS) { while (r == SQL_SUCCESS) {
if (usingSpecialColumns) { if (usingSpecialColumns) {
cName = qGetStringData(hStmt, 1, -1, d->unicode); // column name cName = qGetStringData(hStmt, 1, -1, d->unicode).toString(); // column name
idxName = QString::number(fakeId++); // invent a fake index name idxName = QString::number(fakeId++); // invent a fake index name
} else { } else {
cName = qGetStringData(hStmt, 3, -1, d->unicode); // column name cName = qGetStringData(hStmt, 3, -1, d->unicode).toString(); // column name
idxName = qGetStringData(hStmt, 5, -1, d->unicode); // pk index name idxName = qGetStringData(hStmt, 5, -1, d->unicode).toString(); // pk index name
} }
index.append(rec.field(cName)); index.append(rec.field(cName));
index.setName(idxName); index.setName(idxName);