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https://github.com/CurtTilmes/Perl6-GraphQL

Perl 6 implementation of GraphQL
https://github.com/CurtTilmes/Perl6-GraphQL

graphql graphql-server perl6

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Perl 6 implementation of GraphQL

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Perl 6 GraphQL

==============



[![Build Status](https://travis-ci.org/CurtTilmes/Perl6-GraphQL.svg)](https://travis-ci.org/CurtTilmes/Perl6-GraphQL)



A [Perl 6](https://perl6.org/) implementation of the

[GraphQL](http://graphql.org/) standard.  GraphQL is a query language

for APIs originally created by Facebook.



## Intro



Before we get into all the details, here's the Perl 6 GraphQL "Hello World"

[hello.pl](https://github.com/CurtTilmes/Perl6-GraphQL/blob/master/eg/hello.pl)



```

use GraphQL;

use GraphQL::Server;



class Query

{

    method hello(--> Str) { 'Hello World' }

}



my $schema = GraphQL::Schema.new(Query);



GraphQL-Server($schema);



```



You can run this with a GraphQL query on the command line:

```

$ perl6 hello.pl --help

Usage:

  hello.pl 

  hello.pl [--filename=]

  hello.pl [--port=]



$ perl6 hello.pl '{hello}'

{

  "data": {

    "hello": "Hello World"

  }

}

```



You can even ask for information about the schema and types:

```

$ perl6 hello.pl '{ __schema { queryType { name } } }'

{

  "data": {

    "__schema": {

      "queryType": {

        "name": "Query"

      }

    }

  }

}



$ perl6 hello.pl '{ __type(name: "Query") { fields { name type { name }}}}'

{

  "data": {

    "__type": {

      "fields": [

        {

          "name": "hello",

          "type": {

            "name": "String"

          }

        }

      ]

    }

  }

}

```



## Running as a server



That's fine for the command line, but you can also easily wrap GraphQL

into a web server to expose that API to external clients.  GraphQL::Server

uses the Perl 6 web framework

[Bailador](https://github.com/ufobat/Bailador) to do that:



```

$ ./hello.pl

Entering the development dance floor: http://0.0.0.0:3000

[2016-12-21T13:02:38Z] Started HTTP server.



```



The server takes any GraphQL query sent with HTTP POST to /graphql,

executes it against the GraphQL Schema, and returns the result in

JSON.



There is one additional feature.  If it receives a GET request to

"/graphql", it sends back the

[GraphiQL](https://github.com/graphql/graphiql) graphical interactive

in-browser GraphQL IDE.



![](eg/hello-graphiql.png)



You can use that to explore the schema (though the Hello World schema

is very simple, that won't take long), and interactively construct and

execute GraphQL queries.



## Embedding in a Cro server



As an alternative to Bailador, you can use `Cro::HTTP::Router::GraphQL`

to embed GraphQL into [Cro](http://mi.cro.services/) HTTP routes:



```

use GraphQL;

use Cro::HTTP::Router::GraphQL;

use Cro::HTTP::Router;

use Cro::HTTP::Server;



class Query

{

    method hello(--> Str) { 'Hello World' }

}



my $schema = GraphQL::Schema.new(Query);



my Cro::Service $hello = Cro::HTTP::Server.new:

    :host, :port<10000>,

    application => route

    {

        get -> { redirect '/graphql' }



        get -> 'graphql' { graphiql }



        post -> 'graphql' { graphql($schema) }

    }



$hello.start;



react whenever signal(SIGINT) { $hello.stop; exit; }

```



You can mix/match with other routes you want your server to handle.



There is also a `CroX::HTTP::Transform::GraphQL` you can easily delegate

to from Cro routes:



```

route {

    delegate graphql => CroX::HTTP::Transform::GraphQL.new(:$schema, :graphiql);

}

```



Pass in your GraphQL schema, and optional `:graphiql` to enable

GraphiQL support on an http GET.



`CroX::HTTP::Transform::GraphQL` is a `Cro::HTTP::Transform` that

consumes `Cro::HTTP::Request`s and produces `Cro::HTTP::Response`s.

It is still pretty basic.  A planned enhancement is caching parsed

GraphQL query documents.  (Patches or advice welcome!)



## More documentation



See [eg/usersexample.md](/eg/usersexample.md) for a more complicated example.



See [slides](https://curttilmes.github.com/2017-GraphQL-PHLPM) from a

presentation about Perl 6 GraphQL at the Philadelphia Perl Mongers.



[GraphQL Documentation](/doc/GraphQL.md)



Copyright © 2017 United States Government as represented by the

Administrator of the National Aeronautics and Space Administration.

No copyright is claimed in the United States under Title 17,

U.S.Code. All Other Rights Reserved.