hate

HATEOAS with HAL for Java. Create hypermedia APIs by easily serializing your Java models into HAL JSON.
More info in the wiki.

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Install with Maven

<dependencies>
<dependency>
<groupId>black.door</groupId>
<artifactId>hate</artifactId>
<version>v1r4t5</version>
</dependency>
</dependencies>

Basic usage

Implement the HalResource interface in your model by implementing the location() and representationBuilder() methods. For example:

publicclassOrderimplementsHalResource{
privateintid;
privatedoubletotal;
privateStringcurrency;
privateStringstatus;
//note: Basket and Customer implement HalResourceprivateBasketbasket;
privateCustomercustomer;
...
@OverridepublicURIlocation(){
returnnewURI("/orders/" + id);
}
@OverridepublicHalRepresentationBuilderrepresentationBuilder() {
returnHalRepresentation.builder()
.addProperty("total", total)
.addProperty("currency", currency)
.addProperty("status", status)
.addLink("basket", basket)
.addLink("customer", customer)
.addLink("self", this);
}
}	

Now to get the HalRepresentation of an Order object, simply do HalRepresentation hal = myOrder.asEmbedded(). You can serialize hal using hal.serialize() or with Jackson (eg. new ObjectMapper().writeValueAsString(hal))

The result would look like this:

{
"total": 30,
"currency": "USD",
"status": "shipped",
"_links": {
"basket": {
"href": "/baskets/97212"
},
"self": {
"href": "/orders/123"
},
"customer": {
"href": "/customers/7809"
}
}
}

Paginated Collections

To get a paginated HAL representation of a REST collection, simply use HalRepresentation.paginated(String, String, Stream, long, long).
For example:

Collection<Order> orders;
HalRepresentationhal = HalRepresentation.paginated(
"orders", // the name of the resource collection"/orders", // the path the resource collection can be found atorders.stream(), // the resourcespageNumber,
pageSize// the number of resources per page
).build();

Would give you something like this:

{
"_links": {
"next": {
"href": "/orders?page=2"
},
"self": {
"href": "/orders"
}
},
"_embedded": {
"orders": [
{
"total": 30,
"currency": "USD",
"status": "shipped",
"_links": {
"basket": {
"href": "/baskets/97212"
},
"self": {
"href": "/orders/123"
},
"customer": {
"href": "/customers/7809"
}
}
},
{
"total": 20,
"currency": "USD",
"status": "processing",
"_links": {
"basket": {
"href": "/baskets/97213"
},
"self": {
"href": "/orders/124"
},
"customer": {
"href": "/customers/12369"
}
}
}
]
}
}

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