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
工具。
find_package(Qt6 COMPONENTS GrpcTools REQUIRED)
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
.
注意： there is no explicit support for building gRPC and Protobuf applications using the Qt GRPC module with qmake .
The following CMake commands integrate a gRPC service into a Qt project.
| 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
.
注意：
若
.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.
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>.proto
The
options
argument is a semicolon-separated list of
Options
. It can be passed by prepending the
options
到
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"
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:
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.
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/
.
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.
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.
QML
enables a
QmlClient
generation. The class is inherited from the base
CLIENT
class, but extends it with
QML_ELEMENT
macro, QML properties, and
Q_INVOKABLE
methods. The result of generation may be added into the QML module, that makes QmlClient available as an object from QML. See example of adding the
QmlClient
class into QML module below:
qt_add_protobuf(targetname QML ... ) qt_add_grpc(targetname QML ... )
注意：
for Qt 6.7 only
QmlClient
source code generation is supported.