services-apigateway-code.md

Sample function code

Sample code is available for the following languages.

Topics

• Node.js
• Python 3
• Go

Node.js

The following example processes messages from API Gateway, and manages DynamoDB documents based on the request method.

Example index.js

console.log('Loading function');

var AWS = require('aws-sdk');
var dynamo = new AWS.DynamoDB.DocumentClient();

/**
 * Provide an event that contains the following keys:
 *
 *   - operation: one of the operations in the switch statement below
 *   - tableName: required for operations that interact with DynamoDB
 *   - payload: a parameter to pass to the operation being performed
 */
exports.handler = function(event, context, callback) {
    //console.log('Received event:', JSON.stringify(event, null, 2));

    var operation = event.operation;

    if (event.tableName) {
        event.payload.TableName = event.tableName;
    }

    switch (operation) {
        case 'create':
            dynamo.put(event.payload, callback);
            break;
        case 'read':
            dynamo.get(event.payload, callback);
            break;
        case 'update':
            dynamo.update(event.payload, callback);
            break;
        case 'delete':
            dynamo.delete(event.payload, callback);
            break;
        case 'list':
            dynamo.scan(event.payload, callback);
            break;
        case 'echo':
            callback(null, "Success");
            break;
        case 'ping':
            callback(null, "pong");
            break;
        default:
            callback(`Unknown operation: ${operation}`);
    }
};

Zip up the sample code to create a deployment package. For instructions, see Deploy Node.js Lambda functions with .zip file archives.

Python 3

The following example processes messages from API Gateway, and manages DynamoDB documents based on the request method.

Example LambdaFunctionOverHttps.py

from __future__ import print_function

import boto3
import json

print('Loading function')


def handler(event, context):
    '''Provide an event that contains the following keys:

      - operation: one of the operations in the operations dict below
      - tableName: required for operations that interact with DynamoDB
      - payload: a parameter to pass to the operation being performed
    '''
    #print("Received event: " + json.dumps(event, indent=2))

    operation = event['operation']

    if 'tableName' in event:
        dynamo = boto3.resource('dynamodb').Table(event['tableName'])

    operations = {
        'create': lambda x: dynamo.put_item(**x),
        'read': lambda x: dynamo.get_item(**x),
        'update': lambda x: dynamo.update_item(**x),
        'delete': lambda x: dynamo.delete_item(**x),
        'list': lambda x: dynamo.scan(**x),
        'echo': lambda x: x,
        'ping': lambda x: 'pong'
    }

    if operation in operations:
        return operations[operation](event.get('payload'))
    else:
        raise ValueError('Unrecognized operation "{}"'.format(operation))

Zip up the sample code to create a deployment package. For instructions, see Deploy Python Lambda functions with .zip file archives.

Go

The following example processes messages from API Gateway, and logs information about the request.

Example LambdaFunctionOverHttps.go

import (
    "context"
    "fmt"
    "github.com/aws/aws-lambda-go/events"
    runtime "github.com/aws/aws-lambda-go/lambda"
)

func main() {
    runtime.Start(handleRequest)
}

func handleRequest(ctx context.Context, request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
    fmt.Printf("Processing request data for request %s.\n", request.RequestContext.RequestID)
    fmt.Printf("Body size = %d.\n", len(request.Body))

    fmt.Println("Headers:")
    for key, value := range request.Headers {
        fmt.Printf("    %s: %s\n", key, value)
    }

    return events.APIGatewayProxyResponse{Body: request.Body, StatusCode: 200}, nil
}

Build the executable with go build and create a deployment package. For instructions, see Deploy Go Lambda functions with .zip file archives.