Aggregate (Axon Framework 4.0 API)

Type Parameters:

T - The aggregate root type

All Known Implementing Classes:

AnnotatedAggregate, EventSourcedAggregate, LockAwareAggregate
```
public interface Aggregate<T>
```
Interface that describes an aggregate. An aggregate is an isolated tree of entities that is capable of handling commands. Implementations of this interface defer the actual handling of commands to a wrapped instance of type T or one of its entities.
When a command is dispatched to an aggregate Axon will load the aggregate instance and invoke the related command handler method. It is rarely necessary to interact with aggregates directly. Though it is not recommended it is possible to invoke methods on the wrapped instance using invoke(Function) and execute(Consumer).

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`void`	`execute(Consumer<T> invocation)` Execute a method on the underlying aggregate or one of its instances.
`Object`	`handle(Message<?> message)` Handle the given `message` on the aggregate root or one of its child entities.
`Object`	`identifier()` Get the unique identifier of this aggregate
`default String`	`identifierAsString()` Get the unique identifier of this aggregate, represented as a String.
`<R> R`	`invoke(Function<T,R> invocation)` Invoke a method on the underlying aggregate root or one of its instances.
`boolean`	`isDeleted()` Check if this aggregate has been deleted.
`Class<? extends T>`	`rootType()` Get the class type of the wrapped aggregate root that the Aggregate defers to for command handling.
`String`	`type()` Get the String representation of the aggregate's type.
`Long`	`version()` Get the aggregate's version.

- Method Detail
  - type
```
String type()
```
    Get the String representation of the aggregate's type. This defaults to the simple name of the rootType() unless configured otherwise.
    
    Returns:
    
    The aggregate's type
  - identifierAsString
```
default String identifierAsString()
```
    Get the unique identifier of this aggregate, represented as a String.
    
    Returns:
    
    The aggregate's identifier as a String
  - identifier
```
Object identifier()
```
    Get the unique identifier of this aggregate
    
    Returns:
    
    The aggregate's identifier
  - version
```
Long version()
```
    Get the aggregate's version. For event sourced aggregates this is identical to the sequence number of the last applied event.
    
    Returns:
    
    The aggregate's version
  - handle
```
Object handle(Message<?> message)
       throws Exception
```
    Handle the given message on the aggregate root or one of its child entities.
    
    Parameters:
    
    message - The message to be handled by the aggregate
    
    Returns:
    
    The result of message handling. Might returns null if for example handling a CommandMessage yields no results
    
    Throws:
    
    Exception - in case one is triggered during message processing
  - invoke
```
<R> R invoke(Function<T,R> invocation)
```
    Invoke a method on the underlying aggregate root or one of its instances. Use this over execute(Consumer) to obtain an invocation result, for instance in order to query the aggregate.
    Note that the use of this method is not recommended as aggregates are not meant to be queried. Relying on this method is commonly a sign of design smell.
    
    Type Parameters:
    
    R - The type of the result produced by the given invocation
    
    Parameters:
    
    invocation - The function that performs the actual invocation
    
    Returns:
    
    The invocation result
  - execute
```
void execute(Consumer<T> invocation)
```
    Execute a method on the underlying aggregate or one of its instances.
    Note that the use of this method is not recommended as the wrapped aggregate instance is not meant to be exposed. Relying on this method is commonly a sign of design smell.
    
    Parameters:
    
    invocation - The function that performs the invocation
  - isDeleted
```
boolean isDeleted()
```
    Check if this aggregate has been deleted. This is checked by aggregate repositories when an aggregate is loaded. In case the repository is asked to load a deleted aggregate the repository will refuse by throwing an AggregateDeletedException.
    
    Returns:
    
    true in case the aggregate was deleted, false otherwise
  - rootType
```
Class<? extends T> rootType()
```
    Get the class type of the wrapped aggregate root that the Aggregate defers to for command handling.
    
    Returns:
    
    The aggregate root type

Interface Aggregate<T>

Method Summary

Method Detail

type

identifierAsString

identifier

version

handle

invoke

execute

isDeleted

rootType