tartiflette-aiohttp 0.4.2

Runs a Tartiflette GraphQL Engine through aiohttp


**tartiflette-aiohttp** is a wrapper of [aiohttp](https://github.com/aio-libs/aiohttp/) which includes the [Tartiflette GraphQL Engine](https://github.com/dailymotion/tartiflette), do not hesitate to take a look of the [Tartiflette project](https://github.com/dailymotion/tartiflette).

**Summary**

- [Usage](#usage)
- [Installation](#installation)
- [Installation dependencies](#installation-dependencies)
- [How to use](#how-to-use)
- [Use with built-in Tartiflette Engine](#use-with-built-in-tartiflette-engine)
- [Use with custom Tartiflette engine](#use-with-custom-tartiflette-engine)
- [Tartiflette with subscriptions](#tartiflette-with-subscriptions)
- [Enable GraphiQL handler](#enable-graphiql-handler)

## Usage

```python
# main.py
from aiohttp import web
from tartiflette import Resolver
from tartiflette_aiohttp import register_graphql_handlers

@Resolver("Query.hello")
async def resolver_hello(parent, args, ctx, info):
return "hello " + args["name"]

sdl = """
type Query {
hello(name: String): String
}
"""

web.run_app(
register_graphql_handlers(
web.Application(),
engine_sdl=sdl
)
)
```

Save the file and start the server.

```bash
$ python main.py
======== Running on http://0.0.0.0:8080 ========
(Press CTRL+C to quit)
```

Execute a request to your server
```
curl -v -d '{"query": "query { hello(name: "Chuck") }"}' -H "Content-Type: application/json" http://localhost:8080/graphql
```

## Installation

`tartiflette-aiohttp` is available on [pypi.org](https://pypi.org/project/tartiflette-aiohttp/).

```bash
pip install tartiflette-aiohttp
```

### Installation dependencies

As [Tartiflette](https://github.com/dailymotion/tartiflette) based its Executor engine on *[libgraphqlparser](https://github.com/graphql/libgraphqlparser)*. You'll need these following commands on your environment to use the library. `cmake`, `bison` and `flex`.

*MacOSX*
```bash
brew install cmake flex bison
```

*Ubuntu*
```bash
apt-get install cmake flex bison
```

## How to use

### Use with built-in Tartiflette Engine

The basic and common way to use Tartiflette with aiohttp, is to create an aiohttp `web.Application` and use the `register_graphql_handlers` helper to bind Tartiflette and aiohttp together. `engine_*` parameters will be forwarded to the built-in [tartiflette](https://github.com/dailymotion/tartiflette) engine instance.

```python
from aiohttp import web
from tartiflette_aiohttp import register_graphql_handlers

sdl = """
type Query {
hello(name: String): String
}
"""

ctx = {
'user_service': user_service
}

web.run_app(
register_graphql_handlers(
app=web.Application(),
engine_sdl=sdl,
engine_schema_name="default",
executor_context=ctx,
executor_http_endpoint='/graphql',
executor_http_methods=['POST', 'GET']
)
)
```

**Parameters**:

* **engine_sdl**: Contains the [Schema Definition Language](https://graphql.org/learn/schema/)
- Could be a string which contains the SDL
- Could be an array of string, which contain the SDLs
- Could be a path of an SDL
- Could be an array of paths which contain the SDLs
* **engine_schema_name**: Name of the schema used the built-in engine.
* **executor_context**: Context which will be passed to each resolver. Be default, the context passed to each resolvers, will contain these properties.
- **req**: Request object from aiohttp
- **app**: Application object from aiohttp
* **executor_http_endpoint**: Endpoint where the GraphQL Engine will be attached, by default on `/graphql`
* **executor_http_methods**: HTTP Method where the GraphQL Engine will be attached, by default on **POST** and **GET**.

### Use with custom Tartiflette engine

In the case you already have a Tartiflette Engine instance, or, you do not want to use the built-in instance. You can pass an existing instance to the `register_graphql_handlers` helper.

```python
# main.py
from aiohttp import web
from tartiflette import Resolver, Engine
from tartiflette_aiohttp import register_graphql_handlers

@Resolver("Query.hello")
async def resolver_hello(parent, args, ctx, info):
return "hello " + args["name"]

sdl = """
type Query {
hello(name: String): String
}
"""

engine = Engine(sdl)

ctx = {
'user_service': user_service
}

web.run_app(
register_graphql_handlers(
app=web.Application(),
engine=engine,
executor_context=ctx,
executor_http_endpoint='/graphql',
executor_http_methods=['POST', 'GET']
)
)
```

**Parameters**:

* **engine**: Tartiflette Engine instance
* **executor_context**: Context which will be passed to each resolver. Be default, the context passed to each resolvers, will contain these properties
- **req**: Request object from aiohttp
- **app**: Application object from aiohttp
* **executor_http_endpoint**: Endpoint where the GraphQL Engine will be attached, by default on `/graphql`
* **executor_http_methods**: HTTP Method where the GraphQL Engine will be attached, by default on **POST** and **GET**

### Tartiflette with subscriptions

Tartiflette embeds an easy way to deal with subscription. The only thing to do is
to fill in the `subscription_ws_endpoint` parameter and everything will work out
of the box with `aiohttp` WebSockets. You can see a full example
[here](examples/aiohttp/dogs).

### Enable GraphiQL handler

Tartiflette allows you to set up an instance of GraphiQL easily to quickly test
your queries. The easiest way to do that is to set the `graphiql_enabled`
parameter to `True`. Then, you can customize your GraphiQL instance by filling
the `graphiql_options` parameter as bellow:

```python
from aiohttp import web

from tartiflette_aiohttp import register_graphql_handlers


_SDL = """
type Query {
hello(name: String): String
}
"""

web.run_app(
register_graphql_handlers(
app=web.Application(),
engine_sdl=_SDL,
graphiql_enabled=True,
graphiql_options={ # This is optional
"endpoint": "/explorer", # Default: `/graphiql`,
"default_query": """
query Hello($name: String) {
hello(name: $name)
}
""",
"default_variables": {
"name": "Bob",
},
"default_headers": {
"Authorization": "Bearer <default_token>",
},
},
)
)
```

**Parameters**:

* **engine_sdl**: Contains the [Schema Definition Language](https://graphql.org/learn/schema/)
- Could be a string which contains the SDL
- Could be an array of string, which contain the SDLs
- Could be a path of an SDL
- Could be an array of paths which contain the SDLs
* **graphiql_enabled** *(Optional[bool] = False)*: Determines whether or not we should handle a GraphiQL endpoint
* **graphiql_options** *(Optional[dict] = None)*: Customization options for the GraphiQL instance:
- **endpoint** *(Optional[str] = "/graphiql")*: allows to customize the GraphiQL endpoint
- **default_query** *(Optional[str] = None)*: allows you to pre-fill the GraphiQL interface with a default query
- **default_variables** *(Optional[dict] = None)*: allows you to pre-fill the GraphiQL interface with default variables
- **default_headers** *(Optional[dict] = None)*: allows you to add default headers to each request sent through the GraphiQL instance