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https://github.com/Microsoft/cppgraphqlgen

C++ GraphQL schema service generator
https://github.com/Microsoft/cppgraphqlgen

graphql graphql-tools

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C++ GraphQL schema service generator

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README 

        
# Introduction



![Windows](https://github.com/microsoft/cppgraphqlgen/workflows/Windows/badge.svg)

![macOS](https://github.com/microsoft/cppgraphqlgen/workflows/macOS/badge.svg)

![Linux](https://github.com/microsoft/cppgraphqlgen/workflows/Linux/badge.svg)



[GraphQL](https://graphql.org/) and [React](https://reactjs.org/) go together like peanut butter

and jelly, especially if you use a GraphQL client/compiler like [Relay](http://facebook.github.io/relay/en/)

or [Apollo](https://github.com/apollographql/apollo-client).



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](https://facebook.github.io/relay/docs/en/network-layer.html)/Apollo

[Terminating Link](https://www.apollographql.com/docs/link/overview.html#terminating) 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.



If what you're after is a way to consume a GraphQL service from C++, this project also includes

a `graphqlclient` library and a `clientgen` utility to generate types matching a GraphQL request

document, its variables, and all of the serialization code you need to talk to a `graphqlservice`

implementation. If you want to consume another service, you will need access to the schema definition

(rather than the Introspection query results), and you will need be able to send requests along with

any variables to the service and parse its responses into a `graphql::response::Value` (e.g. with the

`graphqljson` library) in your code.



## Related projects



The most complete examples I've built are related to [GqlMAPI](https://github.com/microsoft/gqlmapi):

- [eMAPI](https://github.com/microsoft/eMAPI): Windows-only Electron app which lets you access

the [MAPI](https://en.wikipedia.org/wiki/MAPI) interface used by

[Microsoft Outlook](https://en.wikipedia.org/wiki/Microsoft_Outlook). Its goal is to be a spiritual

successor to a debugging and diagnostic tool called

[MFCMAPI](https://github.com/stephenegriffin/mfcmapi).

- [electron-gqlmapi](https://github.com/microsoft/electron-gqlmapi): Native module for Electron

which hosts `GqlMAPI` in `eMAPI`. It includes JS libraries for calling the native module across the

Electron IPC channel.

- [Tauri-GqlMAPI](https://github.com/wravery/tauri-gqlmapi): Reimplementation of `eMAPI` built

in [Rust](https://www.rust-lang.org/) and [TypeScript](https://www.typescriptlang.org/) on top of

[Tauri](https://tauri.studio/en).

- [gqlmapi-rs](https://github.com/wravery/gqlmapi-rs): `Rust` crate I built to expose safe

bindings for `GqlMAPI`. It is loosely based on `electron-gqlmapi`, and it is used by

`Tauri-GqlMAPI`.



I created a couple of sample projects to demonstrate integrating the

[schema.today.graphql](./samples/schema.today.graphql) service into an Electron app. The

`schema.today.graphql` schema and service implementation in `TodayMock.*` are focused on testing,

so the specific bootstrapping used in these projects should not be re-used, but you can use them

as a scaffold to start your own integration with Electron or Node.js. They're available under

my personal account, and I recently updated them to match the latest release of `cppgraphqlgen`:

- [electron-cppgraphql](https://github.com/wravery/electron-cppgraphql): Node Native Module which compiles

against the version of the Node headers included in Electron. This was the starting point for

`electron-gqlmapi`, and it is still useful as a sample because it does not depend on a platform-specific

API like `MAPI`, so it works cross-platform.

- [cppgraphiql](https://github.com/wravery/cppgraphiql): Electron app which consumes `electron-cppgraphql` and

exposes an instance of [GraphiQL](https://github.com/graphql/graphiql) on top of it.



Feel free to use either or both of these as a starting point to integrate your own generated

service with `Node`, `Electron`, or `Tauri`. PRs with links to your own samples are always welcome.



# Getting Started



## Installation process



The minimum OS and toolchain versions I've tested with this version of `cppgraphqlgen` are:

- Microsoft Windows: Visual Studio 2019

- Linux: Ubuntu 20.04 LTS with gcc 10.3.0

- macOS: 11 (Big Sur) with AppleClang 13.0.0.



The key compiler requirement is support for C++20 including coroutines and concepts. Some of these compiler

versions still treat coroutine support as experimental, and the CMake configuration can auto-detect that,

but earlier versions of gcc and clang do not seem to have enough support for C++20.



The easiest way to build and install `cppgraphqlgen` is to use [microsoft/vcpkg](https://github.com/microsoft/vcpkg).

See the [Getting Started](https://github.com/microsoft/vcpkg#getting-started) section of the `vcpkg` README

for details. Once you have that configured, run `vcpkg install cppgraphqlgen` (or `cppgraphqlgen:x64-windows`,

`cppgraphqlgen:x86-windows-static`, etc. depending on your platform). That will build and install all of the

dependencies for `cppgraphqlgen`, and then build `cppgraphqlgen` itself without any other setup. The `cppgraphqlgen`

package (and its dependencies) are advertised to the `CMake` `find_package` function through the

`-DCMAKE_TOOLCHAIN_FILE=<...>/scripts/buildsystems/vcpkg.cmake` parameter/variable. There are more details about

this in the `vcpkg` documentation.



If you want to build `cppgraphqlgen` yourself, you can do that with `CMake` from a clone or archive of this repo.

See the [Build and Test](#build-and-test) section below for instructions. You will need to install the dependencies

first where `find_package` can find them. If `vcpkg` works otherwise, you can do that with `vcpkg install pegtl

boost-program-options rapidjson gtest`. Some of these are optional, if for example you do not build the tests. If

`vcpkg` does not work, please see the documentation for each of those dependencies, as well as your

platform/toolchain documentation for perferred installation mechanisms. You may need to build some or all of them

separately from source.



## Software dependencies



The build system for this project uses [CMake](http://www.cmake.org/). You will need to have CMake (at least version

3.15.0) installed, and the library dependencies need to be where CMake can find them. Otherwise you need to disable the

options which depend on them.



Besides the MIT license for this project, if you redistribute any source code or binaries built from these library

dependencies, you should still follow the terms of their individual licenses. As of this writing, this library and

all of its dependencies are available under either the MIT License or the Boost Software License (BSL). Both

licenses roughly mean that you may redistribute them freely as long as you include an acknowledgement along with

the license text. Please see the license or copyright notice which comes with each project for more details.



### graphqlpeg



- GraphQL parsing: [Parsing Expression Grammar Template Library (PEGTL)](https://github.com/taocpp/PEGTL) release 3.2.6,

which is part of [The Art of C++](https://taocpp.github.io/) library collection. I've added this as a sub-module, so you

do not need to install this separately. If you already have 3.2.6 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](https://github.com/Tencent/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](https://www.boost.org/doc/libs/1_82_0/more/getting_started/index.html) for `schemagen`:



- Command line handling: [Boost.Program_options](https://www.boost.org/doc/libs/1_82_0/doc/html/program_options.html).

Run `schemagen -?` to get a list of options. Many of the files in the [samples](samples/) directory were generated

with `schemagen`, you can look at [samples/CMakeLists.txt](samples/CMakeLists.txt) for a few examples of how to call it:

```

Usage:  schemagen [options]   

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 Schema.cpp source file

  --header-dir arg       Target path for the Schema.h header file

  --stubs                Unimplemented fields throw runtime exceptions instead

                         of compiler errors

  --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`).



### clientgen



The `clientgen` utility is based on `schemagen` and shares the same external dependencies. The command line arguments

are almost the same, except it takes an extra file for the request document and there is no equivalent to `--stubs`:

```

Usage:  clientgen [options]    

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

  -r [ --request ] arg   Request document file path

  -o [ --operation ] arg Operation name if the request document contains more

                         than one

  -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 Client.cpp source file

  --header-dir arg       Target path for the Client.h header file

  --no-introspection     Do not expect support for Introspection

```



This utility should output one header and one source file for each request document. A request document may contain more

than one operation, in which case it will output definitions for all of them together. You may limit the output to a

single operation from the request document by specifying the `--operation` (or `-o`) argument with the operation name.



The generated code depends on the `graphqlclient` library for serialization of built-in types. If you link the generated

code, you'll also need to link `graphqlclient`, `graphqlpeg` for the pre-parsed, pre-validated request AST, and

`graphqlresponse` for the `graphql::response::Value` implementation.



Sample output for `clientgen` is in the sub-directories of [samples/client](samples/client), and several of them are

consumed by unit tests in [test/ClientTests.cpp](test/ClientTests.cpp).



### tests (`GRAPHQL_BUILD_TESTS=ON`)



- Unit testing: [Google Test](https://github.com/google/googletest) 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](include/graphqlservice/GraphQLService.h) for the base types implemented in

the `graphql::service` namespace.



Take a look at the [samples/learn](samples/learn) directory, starting with

[StarWarsData.cpp](samples/learn/StarWarsData.cpp) to see a sample implementation of a custom schema defined in

[schema.learn.graphql](samples/learn/schema/schema.learn.graphql). This is the same schema and sample data used in the

GraphQL tutorial on https://graphql.org/learn/. This directory builds an interactive command line application which

can execute query and mutation operations against the sample data in memory.



There are several helper functions for `CMake` declared in

[cmake/cppgraphqlgen-functions.cmake](cmake/cppgraphqlgen-functions.cmake), which is automatically included if you use

`find_package(cppgraphqlgen)` in your own `CMake` project. See

[samples/learn/schema/CMakeLists.txt](samples/learn/schema/CMakeLists.txt) and

[samples/learn/CMakeLists.txt](samples/learn/CMakeLists.txt), or the `CMakeLists.txt` files in some of the

other samples sub-directories for examples of how to use them to automatically rerun the code generators and update

the files in your source directory.



### Migrating from v3.x to main



Please see the [Migration Guide for v4.x](./doc/migration.md) for more details about upgrading to from the `v3.x` branch

to the `main` branch. Active development takes place almost entirely in `main`.



### Additional Documentation



There are some more targeted documents in the [doc](./doc) directory:



* [Awaitable Types](./doc/awaitable.md)

* [Parsing GraphQL](./doc/parsing.md)

* [Query Responses](./doc/responses.md)

* [JSON Representation](./doc/json.md)

* [Field Resolvers](./doc/resolvers.md)

* [Field Parameters](./doc/fieldparams.md)

* [Directives](./doc/directives.md)

* [Subscriptions](./doc/subscriptions.md)



### Samples



All of the samples are under [samples](samples/), with nested sub-directories for generated files:

- [samples/today](samples/today/): There are two different samples generated from

[schema.today.graphql](samples/today/schema.today.graphql) in this directory. The default

[schema](samples/today/schema/) target includes Introspection support (which is the default), while the

[nointrospection](samples/today/nointrospection/) target demonstrates how to disable Introspection support

with the `schemagen --no-introspection` parameter. The mock implementation of the service for both schemas is in

[samples/today/TodayMock.h](samples/today/TodayMock.h) and [samples/today/TodayMock.cpp](samples/today/TodayMock.cpp).

It builds an interactive `sample`/`sample_nointrospection` and `benchmark`/`benchmark_nointrospection` target for

each version, and it uses each of them in several unit tests.

- [samples/client](samples/client/): Several sample queries built with `clientgen` against the

[schema.today.graphql](samples/today/schema.today.graphql) schema shared with [samples/today](samples/today/). It

includes a `client_benchmark` executable for comparison with benchmark executables using the same hardcoded query

in [samples/today/]. The benchmark links with the default [schema](samples/today/schema/) target in

[samples/today](samples/today/) to handle the benchmark query.

- [samples/learn](samples/learn/): Simpler standalone which builds a `learn_star_wars` executable that follows

the tutorial examples on https://graphql.org/learn/.

- [samples/validation](samples/validation/): This schema is based on the examples and counter-examples from the

[Validation](https://spec.graphql.org/October2021/#sec-Validation) section of the October 2021 GraphQL spec. There

is no implementation of this schema, it relies entirely generated stubs (created with `schemagen --stubs`) to build

successfully without defining more than placeholder objects fo the Query, Mutation, and Subscription operations in

[samples/validation/ValidationMock.h](samples/validation/ValidationMock.h). It is used to test the validation logic

with every example or counter-example in the spec in [test/ValidationTests.cpp](test/ValidationTests.cpp).

- [samples/proxy](samples/proxy/) (`GRAPHQL_BUILD_HTTP_SAMPLE=ON`): Generates a `client` and `server` pair of

executables which proxy requests from the `client` to the `server` over HTTP (on port 8080 for localhost). The HTTP

support in both samples comes from [Boost.Beast](https://www.boost.org/doc/libs/1_82_0/libs/beast/doc/html/index.html),

which must be included in your `Boost` installation to build this directory. If you are using `vcpkg`, it will install

the necessary `Boost` components on demand. _Note: This directory uses the Boost Software License because the samples

borrow heavily from examples in the `Boost.Beast` documentation._



# 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/today/sample` or `samples/today/sample_nointrospection`

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]](mailto:[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](https://technet.microsoft.com/en-us/security/dn606155) key, can be found in

the [Security TechCenter](https://technet.microsoft.com/en-us/security/default).



# 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](https://opensource.microsoft.com/codeofconduct/).

For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or

contact [[email protected]](mailto:[email protected]) with any additional questions or comments.