////
This guide is maintained in the main Quarkus repository
and pull requests should be submitted there:
https://github.com/quarkusio/quarkus/tree/master/docs/src/main/asciidoc
////
= Quarkus - Generating JAX-RS resources with Panache

include::./attributes.adoc[]
:extension-status: experimental

A lot of web applications are monotonous CRUD applications with REST APIs that are tedious to write.
To streamline this task, REST Data with Panache extension can generate the basic CRUD endpoints for your entities and repositories.

While this extension is still experimental and provides a limited feature set, we hope to get an early feedback for it.
Currently this extension supports Hibernate ORM and MongoDB with Panache and can generate CRUD resources that work with `application/json` and `application/hal+json` content.

include::./status-include.adoc[]

== Setting up REST Data with Panache

=== Hibernate ORM

* Add the required dependencies to your `pom.xml`
** Hibernate ORM REST Data with Panache extension (`quarkus-hibernate-orm-rest-data-panache`)
** A JDBC driver extension (`quarkus-jdbc-postgresql`, `quarkus-jdbc-h2`, `quarkus-jdbc-mariadb`, ...)
** One of the RESTEasy JSON serialization extensions (`quarkus-resteasy-jackson` or `quarkus-resteasy-jsonb`)

[source,xml]
----
<dependencies>
    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-hibernate-orm-rest-data-panache</artifactId>
    </dependency>
    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-jdbc-postgresql</artifactId>
    </dependency>
    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-resteasy-jackson</artifactId>
    </dependency>
</dependencies>
----

* Implement the Panache entities and/or repositories as explained in the link:hibernate-orm-panache[Hibernate ORM with Panache guide].
* Define the interfaces for generation as explained in the resource generation section.

=== MongoDB

* Add the required dependencies to your `pom.xml`
** MongoDB REST Data with Panache extension (`quarkus-mongodb-rest-data-panache`)
** One of the RESTEasy JSON serialization extensions (`quarkus-resteasy-jackson` or `quarkus-resteasy-jsonb`)

[source,xml]
----
<dependencies>
    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-mongodb-rest-data-panache</artifactId>
    </dependency>
    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-resteasy-jackson</artifactId>
    </dependency>
</dependencies>
----

* Implement the Panache entities and/or repositories as explained in the link:mongodb-panache[MongoDB with Panache guide].
* Define the interfaces for generation as explained in the resource generation section.

== Generating resources

REST Data with Panache generates JAX-RS resources based on the interfaces available in your application.
For each entity and repository that you want to generate, provide a resource interface.
_Do not implement these interfaces and don't provide custom methods because they will be ignored._ You can, however, override the methods from the extended interface in order to customize them (see the section at the end).

=== PanacheEntityResource

If your application has an entity (e.g. `Person`) that extends either `PanacheEntity` or `PanacheEntityBase` class, you could instruct REST Data with Panache to generate its JAX-RS resource with the following interface:

[source,java]
----
public interface PeopleResource extends PanacheEntityResource<Person, Long> {
}
----

=== PanacheRepositoryResource

If your application has a simple entity (e.g. `Person`) and a repository (e.g. `PersonRepository`) that implements either `PanacheRepository` or `PanacheRepositoryBase` interface, you could instruct REST Data with Panache to generate its JAX-RS resource with the following interface:

[source,java]
----
public interface PeopleResource extends PanacheRepositoryResource<PersonRepository, Person, Long> {
}
----

=== PanacheMongoEntityResource

If your application has an entity (e.g. `Person`) that extends either `PanacheMongoEntity` or `PanacheMongoEntityBase` class, you could instruct REST Data with Panache to generate its JAX-RS resource with the following interface:

[source,java]
----
public interface PeopleResource extends PanacheMongoEntityResource<Person, Long> {
}
----

=== PanacheMongoRepositoryResource

If your application has a simple entity (e.g. `Person`) and a repository (e.g. `PersonRepository`) that implements either `PanacheMongoRepository` or `PanacheMongoRepositoryBase` interface, you could instruct REST Data with Panache to generate its JAX-RS resource with the following interface:

[source,java]
----
public interface PeopleResource extends PanacheMongoRepositoryResource<PersonRepository, Person, Long> {
}
----

=== The generated resource

The generated resources will be functionally equivalent for both entities and repositories.
The only difference being the particular data access pattern and data storage in use.

If you have defined one of the `PeopleResource` interfaces mentioned above, this extension will generate its implementation using a particular data access strategy.
The implemented class then will be used by a generated JAX-RS resource, which will look like this:

[source,java]
----
public class PeopleResourceJaxRs { // The actual class name is going to be unique
    @Inject
    PeopleResource resource;

    @GET
    @Path("{id}")
    @Produces("application/json")
    public Person get(@PathParam("id") Long id){
        Person person = resource.get(id);
        if (person == null) {
            throw new WebApplicationException(404);
        }
        return person;
    }

    @GET
    @Produces("application/json")
    public Response list(@QueryParam("sort") List<String> sortQuery,
            @QueryParam("page") @DefaultValue("0") int pageIndex,
            @QueryParam("size") @DefaultValue("20") int pageSize) {
        Page page = Page.of(pageIndex, pageSize);
        Sort sort = getSortFromQuery(sortQuery);
        List<Person> people = resource.list(page, sort);
        // ... build a response with page links and return a 200 response with a list
    }

    @Transactional
    @POST
    @Consumes("application/json")
    @Produces("application/json")
    public Response add(Person personToSave) {
        Person person = resource.add(person);
        // ... build a new location URL and return 201 response with an entity
    }

    @Transactional
    @PUT
    @Path("{id}")
    @Consumes("application/json")
    @Produces("application/json")
    public Response update(@PathParam("id") Long id, Person personToSave) {
        if (resource.get(id) == null) {
            Person person = resource.update(id, personToSave);
            return Response.status(204).build();
        }
        Person person = resource.update(id, personToSave);
        // ... build a new location URL and return 201 response with an entity
    }

    @Transactional
    @DELETE
    @Path("{id}")
    public void delete(@PathParam("id") Long id) {
        if (!resource.delete(id)) {
            throw new WebApplicationException(404);
        }
    }
}
----

== Resource customisation

REST Data with Panache provides a `@ResourceProperties` and `@MethodProperties` annotations that can be used to customize certain features of the resource.
It can be used in your resource interface:

[source,java]
----
@ResourceProperties(hal = true, path = "my-people")
public interface PeopleResource extends PanacheEntityResource<Person, Long> {
    @MethodProperties(path = "all")
    List<Person> list(Page page, Sort sort);

    @MethodProperties(exposed = false)
    boolean delete(Long id);
}
----

=== Available options

`@ResourceProperties`

* `exposed` - whether resource could be exposed. A global resource property that can be overridden for each method. Default is `true`.
* `path` - resource base path. Default path is a hyphenated lowercase resource name without a suffix of `resource` or `controller`.
* `paged` - whether collection responses should be paged or not.
First, last, previous and next page URIs are included in the response headers if they exist.
Request page index and size are taken from the `page` and `size` query parameters that default to `0` and `20` respectively.
Default is `true`.
* `hal` - in addition to the standard `application/json` responses, generates additional methods that can return `application/hal+json` responses if requested via an `Accept` header.
Default is `false`.
* `halCollectionName` - name that should be used when generating a hal collection response. Default name is a hyphenated lowercase resource name without a suffix of `resource` or `controller`.

`@MethodProperties`

* `exposed` - does not expose a particular HTTP verb when set to `false`. Default is `true`.
* `path` - operation path (this is appended to the resource base path). Default is an empty string.

== Query parameters

REST Data with Panache supports the following query parameters with the generated resources.

* `page` - a page number which should be returned by a list operation.
It applies to the paged resources only and is a number starting with 0. Default is 0.
* `size` - a page size which should be returned by a list operation.
It applies to the paged resources only and is a number starting with 1. Default is 20.
* `sort` - a comma separated list of fields which should be used for sorting a result of a list operation.
Fields are sorted in the ascending order unless they're prefixed with a `-`.
E.g. `?sort=name,-age` will sort the result by the name ascending by the age descending.

== Response body examples

As mentioned above REST Data with Panache supports the `application/json` and `application/hal+json` response content types.
Here are a couple of examples of how a response body would look like for the `get` and `list` operations assuming there are five `Person` records in a database.

=== GET /people/1

`Accept: application/json`

[source,json]
----
{
  "id": 1,
  "name": "John Johnson",
  "birth": "1988-01-10"
}
----

`Accept: application/hal+json`

[source,json]
----
{
  "id": 1,
  "name": "John Johnson",
  "birth": "1988-01-10",
  "_links": {
    "self": {
      "href": "http://example.com/people/1"
    },
    "remove": {
      "href": "http://example.com/people/1"
    },
    "update": {
      "href": "http://example.com/people/1"
    },
    "add": {
      "href": "http://example.com/people"
    },
    "list": {
      "href": "http://example.com/people"
    }
  }
}
----

=== GET /people?page=0&size=2

`Accept: application/json`

[source,json]
----
[
  {
    "id": 1,
    "name": "John Johnson",
    "birth": "1988-01-10"
  },
  {
    "id": 2,
    "name": "Peter Peterson",
    "birth": "1986-11-20"
  }
]

----

`Accept: application/hal+json`

[source,json]
----
{
  "_embedded": [
    {
      "id": 1,
      "name": "John Johnson",
      "birth": "1988-01-10",
      "_links": {
        "self": {
          "href": "http://example.com/people/1"
        },
        "remove": {
          "href": "http://example.com/people/1"
        },
        "update": {
          "href": "http://example.com/people/1"
        },
        "add": {
          "href": "http://example.com/people"
        },
        "list": {
          "href": "http://example.com/people"
        }
      }
    },
    {
      "id": 2,
      "name": "Peter Peterson",
      "birth": "1986-11-20",
      "_links": {
        "self": {
          "href": "http://example.com/people/2"
        },
        "remove": {
          "href": "http://example.com/people/2"
        },
        "update": {
          "href": "http://example.com/people/2"
        },
        "add": {
          "href": "http://example.com/people"
        },
        "list": {
          "href": "http://example.com/people"
        }
      }
    }
  ],
  "_links": {
    "add": {
      "href": "http://example.com/people"
    },
    "list": {
      "href": "http://example.com/people"
    },
    "first": {
      "href": "http://example.com/people?page=0&size=2"
    },
    "last": {
      "href": "http://example.com/people?page=2&size=2"
    },
    "next": {
      "href": "http://example.com/people?page=1&size=2"
    }
  }
}
----

Both responses would also contain these headers:

* Link: < http://example.com/people?page=0&size=2 >; rel="first"
* Link: < http://example.com/people?page=2&size=2 >; rel="last"
* Link: < http://example.com/people?page=1&size=2 >; rel="next"

A `previous` link header (and hal link) would not be included, because the previous page does not exist.
