CMake Commands in Qt6 Protobuf

You should call the following CMake commands to use the Qt6::Protobuf module in your project:

 find_package(Qt6 REQUIRED COMPONENTS Protobuf)

 target_link_libraries(mytarget PRIVATE Qt6::Protobuf)

You can use qt-add-protobuf CMake macros. The macros implicitly call Protobuf code generation for qt-project.

The macros usage examples:

 cmake_minimum_required(VERSION 3.16...3.22)
 project(MyThings)

 find_package(Qt6 REQUIRED COMPONENTS Protobuf)
 qt_standard_project_setup()

 qt_add_protobuf(MyMessages
     GENERATE_PACKAGE_SUBFOLDERS
     PROTO_FILES
         path/to/message.proto
         path/to/other_message.proto
     PROTO_INCLUDES
         /path/to/proto/include
 )

 qt_add_executable(MyApp main.cpp)

 target_link_libraries(MyApp PRIVATE MyMessages)

In the example above, we generate a library called MyMessages, which contains the message types defined in the paths passed to the PROTO_FILES option. The GENERATE_PACKAGE_SUBFOLDERS option to generate a folder structure for the generated files. And the PROTO_INCLUDES option tells protoc to look for dependencies or imports in the specified directories. We create a target for an executable called MyApp, which we link to the MyMessages library.

QML extended protobuf example:

 cmake_minimum_required(VERSION 3.16...3.22)
 project(MyThings)

 find_package(Qt6 REQUIRED COMPONENTS Protobuf Quick)
 qt_standard_project_setup()

 qt_add_protobuf(MyMessagesPlugin
     QML
     QML_URI my.messages.module.uri
     PROTO_FILES
         path/to/message.proto
         path/to/other_message.proto
     PROTO_INCLUDES
         /path/to/proto/include
 )

 qt_add_protobuf(MyApp
     QML
     PROTO_FILES
         path/to/internal_message.proto
     PROTO_INCLUDES
         /path/to/proto/include
 )

 qt_add_qml_module(MyApp
     URI example.uri
     VERSION 1.0
     QML_FILES qml/main.qml
 )

 qt_add_executable(MyApp main.cpp)
 target_link_libraries(MyApp PRIVATE Quick)

In the QML extended example above, by the first qt_add_protobuf call, we generate a QML module called MyMessagesPlugin, which contains the message types defined in the paths passed to the PROTO_FILES option. We use the QML option, that enables proto message types registration in the QML context. The registered types will be available in QML by importing a path that is set by the QML_URI. By second qt_add_protobuf call we add auto-generated code into the existing MyApp QML module. The QML_URI is not required in such cases. Finally, we create a target for an executable called MyApp, which has a QML module for the graphical part and loads MyMessagesPlugin into the main.qml file via the my.messages.module.uri import.