Sleemo: AWS AppSync Direct Lambda Resolver Framework

A Simple yet powerful serverless GraphQL framework powered by AWS AppSync Direct Lambda Resolver.

Features

• No need to manually import other resolver functions and manage the tedious if-else based router from the gateway Lambda handler.
• The arguments of AppSync operations(queries and mutations) being parsed and passed to each resolver functions automatically.
• A utility functions provided to easily convert from and to AppSync scalar types such as AWSDateTime or AWSJSON

Installation

pip install sleemo

Usage

Project Structure

An example of the Sleemo project could be structured like below:

/
|-- gatewayLambda.py
|-- resolvers/
|----- getTodo.py
|----- listTodo.py
|----- createTodo.py
|----- updateTodo.py
|----- deleteTodo.py
|-- requirements.txt

An example code with this project structure is given in the next section.

An Example GraphQL Schema

type Todo {
  id: ID!
  author: String!
  title: String!
  content: String
  done: Boolean!
  createdAt: AWSDateTime!
}

input CreateTodoInput {
  author: String!
  title: String!
  content: String
  done: Boolean
}

input UpdateTodoInput {
  author: String
  title: String
  content: String
  done: Boolean
}

type Query {
  getTodo(id: ID!): Todo
  listTodo: [Todo!]!
}

type Mutation {
  createTodo(input: CreateTodoInput!): Todo
  updateTodo(input: UpdateTodoInput!): Todo
  deleteTodo(id: ID!): Todo
}

An Example Python Code

gatewayLambda.py is the default gateway of the AppSync resolver. It receives the event and route this event to appropriate functions.

from sleemo.framework import get_appsync_framework

sleemo = get_appsync_framework(resolver_path='resolvers')

@sleemo.default_gateway()
def handler(event, context):
    return sleemo.resolve(event)

resolver_path represents where your resolver files are located.

Now, let's take a look at how each resolver file lookes like. Sleemo doesn't care of how each resolver function should be implemented. You can use any libraries you prefer to implement your resolvers. Sleemo just passes the operation argument input: CreateTodoInput to createTodo() function with the original event variable.

from sleemo.utils import get_type_utils
from sleemo.framework import get_logger

logger = get_logger()

def createTodo(input, event):

    ## Your business logic here. 
    ## Below is an example of return data

    logger.info('createTodo start')

    utils = get_type_utils(timezone_offset=9)

    todo = {
        'id': utils.createUUID(),
        'author': input['author'],
        'title': input['title'],
        'content': input['content'],
        'done': False,
        'createdAt': utils.createAWSDateTime(),
    }

    logger.info('createTodo end')

    return todo

Let's take another example of the resolver function getTodo().

from sleemo.utils import get_type_utils

def getTodo(id, event):

    ## Your business logic here. 
    ## Below is an example of return data

    utils = get_type_utils(timezone_offset=9)

    todo = {
        'id': utils.createUUID(),
        'author': 'Taewoo Kim',
        'title': 'Sleemo Usage Example',
        'content': 'Simple yet powerful serverless GraphQL framework',
        'done': False,
        'createdAt': utils.createAWSDateTime(),
    }

    return todo

LICENSE

MIT LICENSE