Introduction

GraphQL and React go together like peanut butter and jelly, especially if you use a GraphQL client/compiler like Relay or Apollo.

But GraphQL services are only implemented on the server. When using React Native or React JS in a hybrid application, you typically have a native application which hosts islands or entire pages of UI rendered with React components, and you might like to display content that you've cached offline or that you otherwise generate on the client without needing to declare a separate data interface or require a server round trip to load it.

This project includes a graphqlservice library with the core functionality of a GraphQL service and a schemagen utility to generate types for your custom GraphQL service schema definition. Once you implement the pure virtual methods on the object interfaces and add hooks to the Relay Network Layer/Apollo Terminating Link to call your service, you can use the same GraphQL client code to access your native data source or a GraphQL service online. You might even be able to share some more of that code between a progressive web app and your native/hybrid app.

Getting Started

Related projects

I created a couple of sample projects that work with the latest version to demonstrate integrating the schema.today.graphql service into an Electron app. They're available under my personal account, feel free to use either or both of these as a starting point to integrate your own generated service with Node or Electron. PRs with links to your own samples are always welcome.

• electron-cppgraphql: Node Native Module which compiles against the version of the Node headers included in Electron.
• cppgraphiql: Electron app which consumes electron-cppgraphql and exposes an instance of GraphiQL on top of it.

Installation process

I've tested this on Windows with both Visual Studio 2017 and 2019, and on Linux using an Ubuntu 20.04 LTS instance running in WSL with both gcc 9.3.0 and clang 10.0.0. The key compiler requirement is support for C++17 including std::filesystem, earlier versions of gcc and clang may not have enough support for that.

The easiest way to get all of these and to build cppgraphqlgen in one step is to use microsoft/vcpkg. To install with vcpkg, make sure you've pulled the latest version and then run vcpkg install cppgraphqlgen (or cppgraphqlgen:x64-windows, cppgraphqlgen:x86-windows-static, etc. depending on your platform). To install just the dependencies and work in a clone of this repo, you'll need some subset of vcpkg install pegtl boost-program-options rapidjson gtest. It works for Windows, Linux, and Mac, but if you want to try building for another platform (e.g. Android or iOS), you'll need to do more of this manually.

Manual installation will work best if you clone the GitHub repos for each of the dependencies and follow the installation instructions for each project. You might also be able to find pre-built packages depending on your platform, but the versions need to match.

Software dependencies

The build system for this project uses CMake. You will need to have CMake (at least version 3.8.0) installed, and the library dependencies need to be where CMake can find them. Otherwise you need to disable the options which depend on them.

I also picked a few other projects as dependencies, most of which are optional when consuming this project. If you redistribute any binaries built from these libraries, you should still follow the terms of their individual licenses. As of this writing, this library and all of its redistributable dependencies are available under the MIT license, which means you need to include an acknowledgement along with the license text.

graphqlpeg

• GraphQL parsing: Parsing Expression Grammar Template Library (PEGTL) release 3.2.0, which is part of The Art of C++ library collection. I've added this as a sub-module, so you do not need to install this separately. If you already have 3.2.0 installed where CMake can find it, it will use that instead of the sub-module and avoid installing another copy of PEGTL.

graphqlservice

The core library depends on graphqlpeg and it references the PEGTL headers itself at build time. Both of those mean it depends on PEGTL as well.

graphqljson (GRAPHQL_USE_RAPIDJSON=ON)

• JSON support: RapidJSON release 1.1.0. If you don't need JSON support, you can also avoid installing this dependency. You will need to set GRAPHQL_USE_RAPIDJSON=OFF in your CMake configuration to do that.

schemagen

I'm using Boost for schemagen:

• Command line handling: Boost.Program_options. Run schemagen -? to get a list of options. Many of the files in the samples directory were generated with schemagen, you can look at samples/CMakeLists.txt for a few examples of how to call it:

Usage:  schemagen [options] <schema file> <output filename prefix> <output namespace>
Command line options:
  --version              Print the version number
  -? [ --help ]          Print the command line options
  -v [ --verbose ]       Verbose output including generated header names as
                         well as sources
  -s [ --schema ] arg    Schema definition file path
  -p [ --prefix ] arg    Prefix to use for the generated C++ filenames
  -n [ --namespace ] arg C++ sub-namespace for the generated types
  --source-dir arg       Target path for the <prefix>Schema.cpp source file
  --header-dir arg       Target path for the <prefix>Schema.h header file
  --no-stubs             Generate abstract classes without stub implementations
  --separate-files       Generate separate files for each of the types
  --no-introspection     Do not generate support for Introspection

I've tested this with several versions of Boost going back to 1.65.0. I expect it will work fine with most versions of Boost after that. The Boost dependencies are only used by the schemagen utility at or before your build, so you probably don't need to redistribute it or the Boost libraries with your project.

If you are building shared libraries on Windows (DLLs) using vcpkg or BUILD_SHARED_LIBS=ON in CMake, be aware that this adds a runtime dependency on a Boost DLL. The schemagen tool won't run without it. However, in addition to automating the install of Boost, vcpkg also takes care of installing the dependencies next to schemagen.exe when building the Windows and UWP shared library targets (the platform triplets which don't end in -static).

tests (GRAPHQL_BUILD_TESTS=ON)

• Unit testing: Google Test for the unit testing framework. If you don't want to build or run the unit tests, you can avoid this dependency as well by setting GRAPHQL_BUILD_TESTS=OFF in your CMake configuration.

API references

See GraphQLService.h for the base types implemented in the graphql::service namespace. Take a look at TodayMock.h and TodayMock.cpp to see a sample implementation of a custom schema defined in schema.today.graphql for testing purposes.

Additional Documentation

There are some more targeted documents in the doc directory:

• Parsing GraphQL
• Query Responses
• JSON Representation
• Field Resolvers
• Field Parameters
• Directives
• Subscriptions

Samples

All of the generated files are in the samples directory. There are two different versions of the generated code, one which creates a single pair of files (samples/unified/), and one which uses the --separate-files flag with schemagen to generate individual header and source files (samples/separate/) for each of the object types which need to be implemeneted. The only difference between TodayMock.h with and without IMPL_SEPARATE_TODAY defined should be that the --separate-files option generates a TodayObjects.h convenience header which includes all of the inidividual object header along with the rest of the schema in TodaySchema.h.

Build and Test

Visual Studio on Windows

Use the Open Folder command to open the root of the repo. If you've installed the dependencies with vcpkg and run its Visual Studio integration command, Visual Studio should know how to build each of the targets in this project automatically.

Once you've built the project Visual Studio's Test Explorer window should list the unit tests, and you can run all of them from there.

Command Line on any platform

Your experience will vary depending on your build toolchain. The same instructions should work for any platform that CMake supports. These basic steps will build and run the tests. You can add options to build in another target directory, change the config from Debug (default) to Release, use another build tool like Ninja, etc. If you are using vcpkg to install the dependencies, remember to specify the -DCMAKE_TOOLCHAIN_FILE=... option when you run the initial build configuration.

• Create a build directory: "mkdir build && cd build"
• Configure the build system: "cmake .."
• Tell CMake to invoke the build system: "cmake --build ." You can repeat this step to rebuild your changes.
• CTest comes with CMake and runs the tests: "ctest ." Run this frequently, and make sure it passes before commits.

You can then optionally install the public outputs by configuring it with Release:

• cmake -DCMAKE_BUILD_TYPE=Release ..
• cmake --build . --target install You probably need to use sudo on Unix to do this.

Interactive tests

If you want to try an interactive version, you can run samples/sample and paste in queries against the same mock service or load a query from a file on the command line.

Reporting Security Issues

Security issues and bugs should be reported privately, via email, to the Microsoft Security Response Center (MSRC) at [email protected]. You should receive a response within 24 hours. If for some reason you do not, please follow up via email to ensure we received your original message. Further information, including the MSRC PGP key, can be found in the Security TechCenter.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.