https://github.com/dabit3/this-or-that

This or that - Real-time atomic voting app built with AWS Amplify
https://github.com/dabit3/this-or-that

aws aws-amplify aws-appsyng dynamodb graphql javascript react serverless

Last synced: 4 days ago
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This or that - Real-time atomic voting app built with AWS Amplify

• Host: GitHub
• URL: https://github.com/dabit3/this-or-that
• Owner: dabit3
• Created: 2020-05-21T16:45:28.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2021-06-08T10:35:04.000Z (over 3 years ago)
• Last Synced: 2023-08-03T20:13:05.843Z (over 1 year ago)
• Topics: aws, aws-amplify, aws-appsyng, dynamodb, graphql, javascript, react, serverless
• Language: CSS
• Homepage: https://www.thisorthat.cloud
• Size: 3.63 MB
• Stars: 98
• Watchers: 7
• Forks: 27
• Open Issues: 7
• Metadata Files:
  • Readme: README.md

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README

        
# This or that

Scalable serverless voting app - built with AWS Amplify, AWS AppSync, and Amazon DynamoDB

![This or that](thisorthat.jpg)

## To deploy

You can deploy this app and the back end infrastructure in one of two ways:

1. The Amplify CLI

2. One click deploy button

### Amplify CLI

1. First install and configure the Amplify CLI.

> For a complete walkthrough of how to configure the CLI, see [this video](https://www.youtube.com/watch?v=fWbM5DLh25U)

```sh

$ npm install -g @aws-amplify/cli

$ amplify configure

```

2. Clone the repo, install dependencies

```sh

$ git clone https://github.com/dabit3/this-or-that.git

$ cd this-or-that

$ npm install

```

3. Initialize the app

```sh

$ amplify init

? Enter a name for the environment: (your preferred env name)

? Choose your default editor: (your preferred editor)

? Do you want to use an AWS profile? Yes

? Please choose the profile you want to use: your-profile-name

? Do you want to configure Lambda Triggers for Cognito? No

```

4. Deploy the back end

```sh

$ amplify push --y

```

5. Run the app

```sh

$ npm start

```

### One click deploy

[![amplifybutton](https://oneclick.amplifyapp.com/button.svg)](https://console.aws.amazon.com/amplify/home#/deploy?repo=https://github.com/dabit3/this-or-that)

## About the app

While the voting API is built with DynamoDB and AppSync, the main functionality really is within a single GraphQL resolver that sends an atomic update to DynamoDB.

This atomic update allows the DynamoDB table to stay consistent regardless of the number of other operations that are happening.

### Upvote resolver

__Request mapping template__

```vtl

{

    "version": "2018-05-29",

    "operation": "UpdateItem",

    "key" : {

      "id" : $util.dynamodb.toDynamoDBJson($context.arguments.id)

    },

    "update": {

      "expression" : "set #upvotes = #upvotes + :updateValue",

      "expressionNames" : {

           "#upvotes" : "upvotes"

       },

       "expressionValues" : {

           ":updateValue" : { "N" : 1 }

       }

    }

}

```

__Response mapping template__

```vtl

$util.quiet($ctx.result.put("clientId", "$context.arguments.clientId"))

$util.toJson($ctx.result)

```