Todo app

This example shows how one can make a simple cloud native todo app with a serverless backend written in Go. Backend is built on AWS Lambda and uses DynamoDB as persistent storage. The client part is created using TypeScript & React TodoMVC Example.

Through this example you will learn:

• How to include DynamoDB table to your Mantil project using persistent key/value storage in Mantil APIs and how to perform CRUD operations
• How to deploy a web application on top of AWS Lambda with Mantil

Prerequisites

This example is created with Mantil. To download Mantil CLI on Mac or Linux use Homebrew

brew tap mantil-io/mantil
brew install mantil

or check direct download links.

To deploy this application you will need an AWS account.

Installation

To locally create a new project from this example run:

mantil new app --from todo
cd app

Using the K/V store

In this example we are using a Mantil KV store to persistently store and query todos. Mantil KV is a key-value store backed DynamoDB. When used it becomes part of the Mantil project. DynamoDB table is created on demand, uses the same naming convention as all other Mantil project resources and it is removed when Mantil project stage is destroyed.

First we initialize the store:

kv, _ := mantil.NewKV("todos")

This will create a new DynamoDB table for the stage (if it doesn't already exist) and a todos partition on it.

Now we can use the Put method to add a new todo:

id := uuid.NewString()
kv.Put(id, &TodoItem{
    ID:        id,
    Title:     "Do the laundry",
    Completed: false,
})

To fetch all todos, we can use the FindAll method:

var items []TodoItem
_, err := kv.FindAll(&items)

For more complex queries we can use in-memory filtering (such as in the toggleAll example). Alternatively, we could define a more suitable sort key. For example, instead of just using the generated uuid as the key as above, we could define:

func (t *TodoItem) kvKey() string {
    return fmt.Sprintf("completed:%v-%s", t.Completed, t.ID)
}
...
t := &TodoItem{
    ID:        uuid.NewString(),
    Title:     "Do the laundry",
    Completed: false,
}
kv.Put(t.kvKey(), t)

Now we can query all completed todos by calling:

var items []TodoItem
_, err := kv.Find(&items, mantil.FindBeginsWith, "completed:true")

Deploying the application

Note: If this is the first time you are using Mantil you will need to install Mantil Node on your AWS account. For detailed instructions please follow the setup guide

mantil aws install

Then you can proceed with application deployment

mantil deploy

This command will create a new stage for your project with the default name development and deploy it to your node.

Now you can output the stage endpoint with mantil env -u. This is where the website for this project will be available. The API endpoints can be invoked by specifying the function and method name in the path, for example $(mantil env -u)/todo/get.

Modification

If you want different behavior out of your function you can make necessary changes to your code in the api folder.

The client code is located in client/todo, to build it run:

cd client/todo
npm install
npm run build

This will build the static assets and copy them over to the Mantil public folder. Note that this is optional and only needed if you want to modify the client code. The project already contains prebuilt assets in public so you can start by deploying a new stage immediately.

After each change you have to deploy your changes with mantil deploy, or instruct Mantil to automatically deploy all saved changes with mantil watch.

For more detailed instruction please refer to the Mantil documentation.

Cleanup

To remove the created stage with all resources including created DynamoDB table from your AWS account destroy it with:

mantil stage destroy development

Final thoughts

With this example you learned how to create a serverless todo application with AWS Lambda and Mantil's KV store backed by DynamoDB. Check out our documentation to find more interesting templates.

If you have any questions or comments on this template or would just like to share your view on Mantil contact us at [email protected].