cgql

An implementation of GraphQL Service in C++, made from reference of official specifications! 😎

Getting Started!

CMake

Prerequisites

• C++17 compiler
  • GCC
  • Clang
  • MSVC
• CMake ( >= 3.16 )
• A build tool
  • Make

Downloading CGQL

• Cloning using Git

git clone https://github.com/cgql/cgql

Doing this will clone the repository to your current working directory.

• Using tarball file ( *.tar.gz )

tar -xzvf <file-name>.tar.gz

Download the tarball file from release page and untar it using the above command.

• Using CGQL

CGQL is a statically linked library for Graphql which you can use on your own project to work with GraphQL in C++. That means you will have to link the library with your project

Suppose you have a folder structure like this:

project/
  |-> src/
  | |-> main.cpp
  | |-> CMakeLists.txt
  |-> lib/
  | |-> cgql/ // this is the cloned / untar-ed cgql folder
  | |-> CMakeLists.txt
  |-> CMakeLists.txt

In the root level CMakeLists.txt add

cmake_minimum_required(VERSION 3.16)

project(next_billion_dollar_startup)

# basic configuration for project like C++ standard, etc...
/.../

add_subdirectory(src) # includes "your" source code
add_subdirectory(lib) # includes libraries for your project

The CMakeLists.txt in lib should contain:

add_subdirectory(cgql)

That's it... CGQL is included in your project like magic!

The CMakeLists.txt in src would contain something this:

project(Source)

add_executable(Source main.cpp)

target_link_libraries(
  Source # your project
  cgqlSource # the static library of cgql ( source )
)

Yeah that's it now you can use CGQL in your project.

An example of executing a basic request

#include <cgql/cgql.h>
#include <cgql/parser/parser.h>

using namespace cgql;

int main() {
  // configuration part
  CgqlInstance test;
  // schema
  test.parseSchema(
    "type Person {"
    "  name: String"
    "  age: Int"
    "}"
    ""
    "type Query {"
    "  person(id: Int): Person"
    "}"
  );

  // resolvers
  ResolverMap resolvers {
    {
      "person",
      [](const Args& args) -> Data {
        Int id = fromVariant<Int>(args["id"]); // argument
        ResultMap p {
          {
            { "name", "cw3dv" },
            { "age", 14 }
          }
        };
        return cgqlSMakePtr<ResultMap>(p);
      }
    }
  };
  // TypeOfMap (used for abstract types)
  TypeOfMap typeOfMap;
  // query
  auto query = parse(
    "{"
    "  cw3dv: person {"
    "    name"
    "    age"
    "  }"
    "}"
  );

  // execution
  auto executionResult = test.executeWith(query, resolvers, typeOfMap);
  printResultMap(*executionResult);
  /* prints result to stdout

  cw3dv
    name cw3dv
    age 14

  */ 
}

Finally run:

cmake -B ./build/
cmake --build ./build/
./build/src/Source

Output:

cw3dv
  name cw3dv
  age 14

And there you go, you have a working GraphQL service... :) More to come like networking stuff, better error management, etc...