qt_add_grpc

Generates Qt-based C++ services using a protobuf schema

This command was introduced in Qt 6.5.

Usually qtgrpcgen is invoked through the qt_add_grpc CMake macro.

 qt_add_grpc(<target> <CLIENT|SERVER>
     PROTO_FILES <file> ...
     [PROTO_INCLUDES <path> ...]
     [QML]
     [OUTPUT_DIRECTORY <dir>]
     [GENERATE_PACKAGE_SUBFOLDERS]
     [COPY_COMMENTS]
     [EXPORT_MACRO <infix>]
     [OUTPUT_HEADERS <var>]
     [OUTPUT_TARGETS <var>]
 )

The source files are created by qtgrpcgen and added to the target. If the target already exists, the files are added to the target source list. If the target doesn't exist, it is created as a library which you must link to.

The gRPC library that is generated using the qt_add_grpc command refers to the protobuf symbols that are used in service calls. This means you either need to use a common target in both qt_add_protobuf and qt_add_grpc calls or link the generated protobuf library to the gRPC one.

Considering the above statement you may reuse the target for both protobuf and gRPC client code:

 # Generate the protobuf types first
 qt_add_protobuf(test_service_client
     PROTO_FILES
         test_service.protobuf
 )
 ...
 # Reuse the protobuf target and extend it with gRPC client
 # functionality
 qt_add_grpc(test_service_client CLIENT
     PROTO_FILES
         test_service.protobuf
 )

If you want to have separate targets then you need to link the gRPC client target to the protobuf one:

 # Generate the protobuf types first
 qt_add_protobuf(test_service_protobuf
     PROTO_FILES
         test_service.protobuf
 )
 ...
 # Add separate target with the generated code of the gRPC client.
 qt_add_grpc(test_service_client CLIENT
     PROTO_FILES
         test_service.protobuf
 )
 target_link_libraries(test_service_client PRIVATE test_service_protobuf)

Arguments

• PROTO_FILES specifies the list of .proto files used by the code generation procedure.
• PROTO_INCLUDES specifies the list of directories to be searched for protobuf dependencies.

  Note: The location of the PROTO_FILES is implicitly considered part of the protobuf include path.

• QML enables the generation of a QML client for the gRPC service.
• OUTPUT_DIRECTORY defines the directory where the generated files will be placed. By default, the current build directory is used.
• GENERATE_PACKAGE_SUBFOLDERS uses the package name specifier from the .proto files to create the folder structure for the generated files. For example, if the package is defined as: package io.qt.test, the generated files will be placed in OUTPUT_DIRECTORY/io/qt/test/.
• COPY_COMMENTS copies comments from the .proto files into the generated code.
• EXPORT_MACRO applies only when creating a new shared library from the <target>. This option specifies the base name for the export macro used in the generated code. The final macro name is constructed as QPB_<EXPORT_MACRO>_EXPORT. If this option is not set, the target name is used as EXPORT_MACRO.

  Read Creating Shared Libraries for further in-depth information.

• OUTPUT_HEADERS specifies a variable that will store the list of generated headers. This list can be useful for defining custom project install rules.
• OUTPUT_TARGETS specifies a variable that will store the list of generated targets. This list can be useful for defining custom project install rules.