doc: active record and repository patterns

Fixes quarkusio#6135 and quarkusio#6945 WIP Apply suggestions from code review will be squashed later Co-Authored-By: Georgios Andrianakis <[email protected]>
loicmathieu · Feb 26, 2020 · 737a697 · 737a697
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diff --git a/docs/src/main/asciidoc/hibernate-orm-panache.adoc b/docs/src/main/asciidoc/hibernate-orm-panache.adoc
@@ -43,13 +43,26 @@ Does this look interesting? Read on!
 
 NOTE: the `list()` method might be surprising at first. It takes fragments of HQL (JP-QL) queries and contextualizes the rest. That makes for very concise but yet readable code.
 
+NOTE: what was described above is essentially the link:https://www.martinfowler.com/eaaCatalog/activeRecord.html[active record pattern], sometimes just called the entity pattern.
+Hibernate with Panache also allows for the use of the more classical link:https://martinfowler.com/eaaCatalog/repository.html[repository pattern] via `PanacheRepository`.
+
+== Solution
+
+We recommend that you follow the instructions in the next sections and create the application step by step.
+However, you can go right to the completed example.
+
+Clone the Git repository: `git clone {quickstarts-clone-url}`, or download an {quickstarts-archive-url}[archive].
+
+The solution is located in the `hibernate-orm-panache-quickstart` {quickstarts-tree-url}/hibernate-orm-panache-quickstart[directory].
+
+
 == Setting up and configuring Hibernate ORM with Panache
 
 To get started:
 
 * add your settings in `{config-file}`
-* annotate your entities with `@Entity` and make them extend `PanacheEntity`
-* place your entity logic in static methods in your entities
+* annotate your entities with `@Entity`
+* make your entities extend `PanacheEntity` (optional if you are using the repository pattern)
 
 Follow the link:hibernate-orm#setting-up-and-configuring-hibernate-orm[Hibernate set-up guide for all configuration].
 
@@ -89,7 +102,9 @@ quarkus.datasource.password = connor
 quarkus.hibernate-orm.database.generation = drop-and-create
 ----
 
-== Defining your entity
+== Solution 1: using the active record pattern
+
+=== Defining your entity
 
 To define a Panache entity, simply extend `PanacheEntity`, annotate it with `@Entity` and add your
 columns as public fields:
@@ -131,9 +146,9 @@ And thanks to our field access rewrite, when your users read `person.name` they
 and similarly for field writes and the setter.
 This allows for proper encapsulation at runtime as all fields calls will be replaced by the corresponding getter/setter calls.
 
-== Most useful operations
+=== Most useful operations
 
-Once you have written your entity, here are the most common operations you will be able to do:
+Once you have written your entity, here are the most common operations you will be able to perform:
 
 [source,java]
 ----
@@ -198,8 +213,194 @@ List<String> namesButEmmanuels = persons
 
 NOTE: The `stream` methods require a transaction to work.
 
+=== Adding entity methods
+
+Add custom queries on your entities inside the entities themselves.
+That way, you and your co-workers can find them easily, and queries are co-located with the object they operate on.
+Adding them as static methods in your entity class is the Panache Active Record way.
+
+[source,java]
+----
+@Entity
+public class Person extends PanacheEntity {
+    public String name;
+    public LocalDate birth;
+    public Status status;
+
+    public static Person findByName(String name){
+        return find("name", name).firstResult();
+    }
+
+    public static List<Person> findAlive(){
+        return list("status", Status.Alive);
+    }
+
+    public static void deleteStefs(){
+        delete("name", "Stef");
+    }
+}
+----
+
+== Solution 2: using the repository pattern
+
+
+=== Defining your entity
+
+When using the repository pattern, you can define your entities as regular JPA entities.
+
+[source,java]
+----
+@Entity
+public class Person {
+    @Id @GeneratedValue private Long id;
+    private String name;
+    private LocalDate birth;
+    private Status status;
+
+    public Long getId(){
+        return id;
+    }
+    public void setId(Long id){
+        this.id = id;
+    }
+    public String getName() {
+        return name;
+    }
+    public void setName(String name) {
+        this.name = name;
+    }
+    public LocalDate getBirth() {
+        return birth;
+    }
+    public void setBirth(LocalDate birth) {
+        this.birth = birth;
+    }
+    public Status getStatus() {
+        return status;
+    }
+    public void setStatus(Status status) {
+        this.status = status;
+    }
+}
+----
+
+TIP: If you don't want to bother defining getters/setters for your entities, you can make them extend `PanacheEntityBase` and
+Quarkus will generate them for you. You can even extend `PanacheEntity` and take advantage of the default ID it provides.
+
+=== Defining your repository
+
+When using Repositories, you get the exact same convenient methods as with the active record pattern, injected in your Repository,
+by making them implements `PanacheRepository`:
+
+[source,java]
+----
+@ApplicationScoped
+public class PersonRepository implements PanacheRepository<Person> {
+
+   // put your custom logic here as instance methods
+
+   public Person findByName(String name){
+       return find("name", name).firstResult();
+   }
+
+   public List<Person> findAlive(){
+       return list("status", Status.Alive);
+   }
+
+   public void deleteStefs(){
+       delete("name", "Stef");
+  }
+}
+----
+
+All the operations that are defined on `PanacheEntityBase` are available on your repository, so using it
+is exactly the same as using the active record pattern, except you need to inject it:
+
+[source,java]
+----
+@Inject
+PersonRepository personRepository;
+
+@GET
+public long count(){
+    return personRepository.count();
+}
+----
+
+=== Most useful operations
+
+Once you have written your repository, here are the most common operations you will be able to perform:
+
+[source,java]
+----
+// creating a person
+Person person = new Person();
+person.name = "Stef";
+person.birth = LocalDate.of(1910, Month.FEBRUARY, 1);
+person.status = Status.Alive;
+
+// persist it
+personRepository.persist(person);
+
+// note that once persisted, you don't need to explicitly save your entity: all
+// modifications are automatically persisted on transaction commit.
+
+// check if it's persistent
+if(personRepository.isPersistent(person)){
+    // delete it
+    personRepository.delete(person);
+}
+
+// getting a list of all Person entities
+List<Person> allPersons = personRepository.listAll();
+
+// finding a specific person by ID
+person = personRepository.findById(personId);
+
+// finding a specific person by ID via an Optional
+Optional<Person> optional = personRepository.findByIdOptional(personId);
+person = optional.orElseThrow(() -> new NotFoundException());
+
+// finding all living persons
+List<Person> livingPersons = personRepository.list("status", Status.Alive);
+
+// counting all persons
+long countAll = personRepository.count();
+
+// counting all living persons
+long countAlive = personRepository.count("status", Status.Alive);
+
+// delete all living persons
+personRepository.delete("status", Status.Alive);
+
+// delete all persons
+personRepository.deleteAll();
+
+// update all living persons
+personRepository.update("name = 'Moral' where status = ?1", Status.Alive);
+
+----
+
+All `list` methods have equivalent `stream` versions.
+
+[source,java]
+----
+Stream<Person> persons = personRepository.streamAll();
+List<String> namesButEmmanuels = persons
+    .map(p -> p.name.toLowerCase() )
+    .filter( n -> ! "emmanuel".equals(n) )
+    .collect(Collectors.toList());
+----
+
+NOTE: The `stream` methods require a transaction to work.
+
+NOTE: The rest of the documentation show usages based on the active record pattern only,
+but keep in mind that they can be performed with the repository pattern as well.
+The repository pattern examples have been omitted for brevity. 
+
+== Advanced Query
 
-== Paging
+=== Paging
 
 You should only use `list` and `stream` methods if your table contains small enough data sets. For larger data
 sets you can use the `find` method equivalents, which return a `PanacheQuery` on which you can do paging:
@@ -236,7 +437,7 @@ return Person.find("status", Status.Alive)
 
 The `PanacheQuery` type has many other methods to deal with paging and returning streams.
 
-== Sorting
+=== Sorting
 
 All methods accepting a query string also accept the following simplified query form:
 
@@ -257,35 +458,7 @@ List<Person> persons = Person.list("status", Sort.by("name").and("birth"), Statu
 
 The `Sort` class has plenty of methods for adding columns and specifying sort direction.
 
-== Adding entity methods
-
-In general, we recommend not adding custom queries for your entities outside of the entities themselves,
-to keep all model queries close to the models they operate on. So we recommend adding them as static methods
-in your entity class:
-
-[source,java]
-----
-@Entity
-public class Person extends PanacheEntity {
-    public String name;
-    public LocalDate birth;
-    public Status status;
-
-    public static Person findByName(String name){
-        return find("name", name).firstResult();
-    }
-
-    public static List<Person> findAlive(){
-        return list("status", Status.Alive);
-    }
-
-    public static void deleteStefs(){
-        delete("name", "Stef");
-    }
-}
-----
-
-== Simplified queries
+=== Simplified queries
 
 Normally, HQL queries are of this form: `from EntityName [where ...] [order by ...]`, with optional elements
 at the end.
@@ -311,7 +484,7 @@ Order.find("select distinct o from Order o left join fetch o.lineItems");
 Order.update("update from Person set name = 'Moral' where status = ?", Status.Alive);
 ----
 
-== Query parameters
+=== Query parameters
 
 You can pass query parameters by index (1-based) as shown below:
 
@@ -345,55 +518,6 @@ Person.find("name = :name and status = :status",
 
 Every query operation accepts passing parameters by index (`Object...`), or by name (`Map<String,Object>` or `Parameters`).
 
-== The DAO/Repository option
-
-Repository is a very popular pattern and can be very accurate for some use case, depending on
-the complexity of your needs.
-
-Whether you want to use the Entity based approach presented above or a more traditional Repository approach, it is up to you,
-Panache and Quarkus have you covered either way.
-
-If you lean towards using Repositories, you can get the exact same convenient methods injected in your Repository by making it
-implement `PanacheRepository`:
-
-[source,java]
-----
-@ApplicationScoped
-public class PersonRepository implements PanacheRepository<Person> {
-
-   // put your custom logic here as instance methods
-
-   public Person findByName(String name){
-       return find("name", name).firstResult();
-   }
-
-   public List<Person> findAlive(){
-       return list("status", Status.Alive);
-   }
-
-   public void deleteStefs(){
-       delete("name", "Stef");
-  }
-}
-----
-
-Absolutely all the operations that are defined on `PanacheEntityBase` are available on your DAO, so using it
-is exactly the same except you need to inject it:
-
-[source,java]
-----
-@Inject
-PersonRepository personRepository;
-
-@GET
-public long count(){
-    return personRepository.count();
-}
-----
-
-So if Repositories are your thing, you can keep doing them. Even with repositories, you can keep your entities as
-subclasses of `PanacheEntity` in order to get the ID and public fields working, but you can even skip that and
-go back to specifying your ID and using getters and setters if that's your thing. Use what works for you.
 
 == Transactions
 
@@ -428,9 +552,9 @@ public void create(Parameter parameter){
 
 Panache provides direct support for database locking with your entity/repository, using `findById(Object, LockModeType)` or `find().withLock(LockModeType)`.
 
-The following examples are for the entity pattern but the same can be used with repositories.
+The following examples are for the entity pattern, but the same can be used with repositories.
 
-== First: Locking using findById().
+=== First: Locking using findById().
 
 [source,java]
 ----
@@ -447,7 +571,7 @@ public class PersonEndpoint {
 }
 ----
 
-== Second: Locking in a find().
+=== Second: Locking in a find().
 
 [source,java]
 ----
@@ -531,9 +655,9 @@ a custom ID strategy, you can extend `PanacheEntityBase` instead and handle the
 - Use public fields. Get rid of dumb getter and setters. Under the hood, we will generate all getters and setters
 that are missing, and rewrite every access to these fields to use the accessor methods. This way you can still
 write _useful_ accessors when you need them, which will be used even though your entity users still use field accesses.
-- Don't use DAOs or Repositories: put all your entity logic in static methods in your entity class. Your entity superclass
-comes with lots of super useful static methods and you can add your own in your entity class. Users can just start using
-your entity `Person` by typing `Person.` and getting completion for all the operations in a single place.
+- With the active record pattern: put all your entity logic in static methods in your entity class and don't create DAOs.
+Your entity superclass comes with lots of super useful static methods, and you can add your own in your entity class.
+Users can just start using your entity `Person` by typing `Person.` and getting completion for all the operations in a single place.
 - Don't write parts of the query that you don't need: write `Person.find("order by name")` or
 `Person.find("name = ?1 and status = ?2", "stef", Status.Alive)` or even better
 `Person.find("name", "stef")`.
@@ -547,4 +671,3 @@ If you define your entities in the same project where you build your Quarkus app
 If the entities come from external projects or jars, you can make sure that your jar is treated like a Quarkus application library
 by indexing it via Jandex, see link:cdi-reference#how-to-generate-a-jandex-index[How to Generate a Jandex Index] in the CDI guide.
 This will allow Quarkus to index and enhance your entities as if they were inside the current project.
-