The qtgrpcgen Tool▲
The qtgrpcgen tool can be used to generate Qt GRPC service classes from a protobuf schema. The tool is provided by the CMake Qt6::GrpcTools package. It works as an extension to Google's protoc tool.
find_package(Qt6 COMPONENTS GrpcTools REQUIRED)Usage▲
Qt provides CMake functions that ease the use of the qtgrpcgen tool. When using CMake as a build tool you should prefer using the Qt CMake API. For build systems other than CMake, adapt the commands described in Running qtgrpcgen manually.
there is no explicit support for building gRPC and Protobuf applications using the Qt GRPC module with qmake.
CMake▲
The following CMake commands integrate a gRPC service into a Qt project.
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qt_add_grpc: Generates Qt-based C++ services using a protobuf schema
Usually qtgrpcgen would be invoked through CMake using the qt_add_grpc macro, as shown in the following example:
cmake_minimum_required(VERSION 3.16...3.22)
project(MyProject)
find_package(Qt6 REQUIRED COMPONENTS Protobuf Grpc)
qt_standard_project_setup()
qt_add_protobuf(MyProtoMessageLib
PROTO_FILES
path/to/helloworld.proto
PROTO_INCLUDES
path/to/proto/include
)
qt_add_grpc(MyGrpcClient CLIENT
PROTO_FILES
path/to/helloworld.proto
PROTO_INCLUDES
path/to/proto/include
)
qt_add_executable(MyApp main.cpp)
target_link_libraries(MyApp PRIVATE MyGrpcClient MyProtoMessageLib Qt6::Protobuf)The example above calls the qt_add_grpc() CMake function to generate a library called MyGrpcClient.
if the .proto file API contains messages, then the qt_add_protobuf() CMake function should be called to generate protobuf message classes for the project.
Finally, the example creates a target for an executable called MyApp which links to the MyGrpcClient and MyProtoMessageLib libraries.
Running qtgrpcgen manually▲
protoc --plugin=protoc-gen-qtgrpc=<path/to/bin/>qtgrpcgen \
--qtgrpc_out="[<options>:]<output_dir>" \
[--qtgrpc_opt="<options>"] \
[-I/extra/proto/include/path] \
<protofile>.protoThe options argument is a semicolon-separated list of Options. It can be passed by prepending the options to the output_dir argument, delimited by a colon, or through a separate argument, --qtgrpc_opt. You also can pass the corresponding keys as the QT_GRPC_OPTIONS environment variable. Keys must be presented as a semicolon-separated list:
export QT_GRPC_OPTIONS="COPY_COMMENTS;GENERATE_PACKAGE_SUBFOLDERS;EXTRA_NAMESPACE=MyTopLevelNamespace"Options▲
The generator supports options that can be provided to tune generation. Options have direct aliases in the qt_add_grpc function. The following options are supported:
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COPY_COMMENTS Copies comments from .proto files. If provided in the parameter list, comments related to messages and fields are copied to generated header files.
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GENERATE_PACKAGE_SUBFOLDERS generates a folder structure for the generated files matching the .proto file's package name. For example package io.qt.test; would put the generated files into io/qt/test/.
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EXTRA_NAMESPACE is an optional namespace that will be used for the generated classes. The classes are always generated in a namespace whose name is the same as the package name specified in the .proto file. If this option is used then everything will be nested inside the extra namespace.
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EXPORT_MACRO is the base name of the symbol export macro used for the generated code. The generated macro name is constructed as QPB_<EXPORT_MACRO>_EXPORT. If the option is not set, the macro is not generated.