Spring Boot HATEOAS example

Small example how HATEOAS can be implemented using Spring Boot and Spring HATEOAS.

Peanut Bowl Scenario

Let's say we are able to create bowls and fill them with peanuts. Anf of course we can snack them ;)

Create a bowl

Let's put an empty bowl on the table.

curl -X POST http://localhost:8080/bowls

The response always contains the current bowl resource, you can find e.g. the bowl id for further steps

Fill a bowl with peanuts

No one needs empty bowls, let's fill it with peanuts.

curl -X PUT http://localhost:8080/bowls/3105ec9b-9f05-49d0-9918-d4313fd29140/fillPeanuts -H "Content-Type: application/json" -d '{"peanuts":10}'

Let's check our peanut level

curl http://localhost:8080/bowls/3105ec9b-9f05-49d0-9918-d4313fd29140

Take out peanuts

We can only snack peanuts, if the bowl is not empty.

curl -X POST http://localhost:8080/bowls/3105ec9b-9f05-49d0-9918-d4313fd29140/snackPeanuts -H "Content-Type: application/json" -d '{"peanuts":10}'

Remove a bowl

We can only remove bowls, if they are empty.

curl -X DELETE http://localhost:8080/bowls/3105ec9b-9f05-49d0-9918-d4313fd29140

HAL representation

The responses should all have some links based on the HAL specification:

curl http://localhost:8080/bowls/3105ec9b-9f05-49d0-9918-d4313fd29140

{
    "id":"16a9f13b-6dd1-4586-9193-d2f22286bf8a",
    "peanuts":0,
    "_links": {
        "self": {
            "href":"http://localhost:8080/bowls/16a9f13b-6dd1-4586-9193-d2f22286bf8a"
        },
        "fill": {
            "href":"http://localhost:8080/bowls/16a9f13b-6dd1-4586-9193-d2f22286bf8a/fillPeanuts"
        },
        "delete":{
            "href":"http://localhost:8080/bowls/16a9f13b-6dd1-4586-9193-d2f22286bf8a"
        }
    }
}

The links existence depends on the business logic described above.