- Qt 6.10
- Qt Qml
- C++ Classes
- QQmlInfo
- Qt 6.10.2 Reference Documentation

# QQmlInfo Class

The QQmlInfo class allows logging of QML-related messages. More...

Header: | `#include <QQmlInfo>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Qml)` `target_link_libraries(mytarget PRIVATE Qt6::Qml)`
qmake: | `QT += qml`

## Related Non-Members

QQmlInfo | qmlDebug(const QObject *object)
QQmlInfo | qmlInfo(const QObject *object)
QQmlInfo | qmlWarning(const QObject *object)

## Detailed Description

QQmlInfo is an opaque handle for QML-related diagnostic messages. You can use the `<<` operator to add content to the message. When the QQmlInfo object is destroyed, it prints the resulting message along with information on the context.

See also qmlDebug, qmlInfo, and qmlWarning.

## Related Non-Members

### QQmlInfo qmlDebug(const QObject *object)

Prints debug messages that include the file and line number for the specified QML object.

When QML types produce logging messages, it improves traceability if they include the QML file and line number on which the particular instance was instantiated.

To include the file and line number, an object must be passed. If the file and line number is not available for that instance (either it was not instantiated by the QML engine or location information is disabled), "unknown location" will be used instead.

For example,

     qmlDebug(object) << "Internal state: 42";

prints

     QML MyCustomType (unknown location): Internal state: 42

See also qmlInfo and qmlWarning.

### QQmlInfo qmlInfo(const QObject *object)

Prints informational messages that include the file and line number for the specified QML object.

When QML types produce logging messages, it improves traceability if they include the QML file and line number on which the particular instance was instantiated.

To include the file and line number, an object must be passed. If the file and line number is not available for that instance (either it was not instantiated by the QML engine or location information is disabled), "unknown location" will be used instead.

For example,

     qmlInfo(object) << tr("component property is a write-once property");

prints

     QML MyCustomType (unknown location): component property is a write-once property

Note: In versions prior to Qt 5.9, qmlInfo reported messages using a warning QtMsgType. For Qt 5.9 and above, qmlInfo uses an info QtMsgType. To send warnings, use qmlWarning.

See also qmlDebug and qmlWarning.

### QQmlInfo qmlWarning(const QObject *object)

Prints warning messages that include the file and line number for the specified QML object.

When QML types produce logging messages, it improves traceability if they include the QML file and line number on which the particular instance was instantiated.

To include the file and line number, an object must be passed. If the file and line number is not available for that instance (either it was not instantiated by the QML engine or location information is disabled), "unknown location" will be used instead.

For example,

     qmlInfo(object) << tr("property cannot be set to 0");

prints

     QML MyCustomType (unknown location): property cannot be set to 0

See also qmlDebug and qmlInfo.