DataContext (Jmix-ui 1.0 API)

All Known Implementing Classes:

DataContextImpl, NoopDataContext
```
@InstallSubject(value="commitDelegate")
public interface DataContext
```
Interface for tracking changes in entities loaded to the client tier.
Within DataContext, an entity with the given identifier is represented by a single object instance, no matter where and how many times it is used in object graphs.

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static class`	`DataContext.ChangeEvent` Event sent when the context detects changes in an entity, a new instance is merged or an entity is removed.
`static class`	`DataContext.PostCommitEvent` Event sent after committing changes.
`static class`	`DataContext.PreCommitEvent` Event sent before committing changes.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`io.jmix.core.common.event.Subscription`	`addChangeListener(java.util.function.Consumer<DataContext.ChangeEvent> listener)` Adds a listener to `DataContext.ChangeEvent`.
`io.jmix.core.common.event.Subscription`	`addPostCommitListener(java.util.function.Consumer<DataContext.PostCommitEvent> listener)` Adds a listener to `DataContext.PostCommitEvent`.
`io.jmix.core.common.event.Subscription`	`addPreCommitListener(java.util.function.Consumer<DataContext.PreCommitEvent> listener)` Adds a listener to `DataContext.PreCommitEvent`.
`void`	`clear()` Evicts all tracked entities.
`io.jmix.core.EntitySet`	`commit()` Commits changed and removed instances to the middleware.
`boolean`	`contains(java.lang.Object entity)` Returns true if the context contains the given entity (distinguished by its class and id).
`<T> T`	`create(java.lang.Class<T> entityClass)` Creates an entity instance and merges it into the context.
`void`	`evict(java.lang.Object entity)` Removes the entity from the context so the context stops tracking it.
`void`	`evictModified()` Clears the lists of created/modified/deleted entities and evicts these entities.
`<T> T`	`find(java.lang.Class<T> entityClass, java.lang.Object entityId)` Returns an entity instance by its class and id.
`<T> T`	`find(T entity)` Returns the instance of entity with the same id if it exists in this context.
`java.util.function.Function<io.jmix.core.SaveContext,java.util.Set<java.lang.Object>>`	`getCommitDelegate()` Returns a function which will be used to commit data instead of standard implementation.
`java.util.Set<java.lang.Object>`	`getModified()` Returns an immutable set of entities registered as modified.
`DataContext`	`getParent()` Returns a parent context, if any.
`java.util.Set<java.lang.Object>`	`getRemoved()` Returns an immutable set of entities registered for removal.
`boolean`	`hasChanges()` Returns true if the context has detected changes in the tracked entities.
`boolean`	`isModified(java.lang.Object entity)` Returns true if the context has detected changes in the given entity.
`boolean`	`isRemoved(java.lang.Object entity)` Returns true if the context has registered removal of the given entity.
`io.jmix.core.EntitySet`	`merge(java.util.Collection entities)` Merge the given entities into the context.
`io.jmix.core.EntitySet`	`merge(java.util.Collection entities, MergeOptions options)` Merge the given entities into the context.
`<T> T`	`merge(T entity)` Same as `merge(Object, MergeOptions)` with default options.
`<T> T`	`merge(T entity, MergeOptions options)` Merge the given entity into the context.
`void`	`remove(java.lang.Object entity)` Removes the entity from the context and registers it as deleted.
`void`	`setCommitDelegate(java.util.function.Function<io.jmix.core.SaveContext,java.util.Set<java.lang.Object>> delegate)` Sets a function which will be used to commit data instead of standard implementation.
`void`	`setModified(java.lang.Object entity, boolean modified)` Registers or unregisters the given entity as modified.
`void`	`setParent(DataContext parentContext)` Sets the parent context.

- Method Detail
  - find
```
@Nullable
<T> T find(java.lang.Class<T> entityClass,
                     java.lang.Object entityId)
```
    Returns an entity instance by its class and id.
    
    Returns:
    
    entity instance or null if there is no such entity in the context
  - find
```
@Nullable
<T> T find(T entity)
```
    Returns the instance of entity with the same id if it exists in this context.
    
    Returns:
    
    entity instance or null if there is no such entity in the context
  - contains
```
boolean contains(java.lang.Object entity)
```
    Returns true if the context contains the given entity (distinguished by its class and id).
  - merge
```
@CheckReturnValue
<T> T merge(T entity,
                              MergeOptions options)
```
    Merge the given entity into the context. The whole object graph with all references will be merged.
    If an entity with the same identifier already exists in the context, the passed entity state is copied into it and the existing instance is returned. Otherwise, a copy of the passed instance is registered in the context and returned.
    If the given instance is new and the context doesn't contain an instance with the same identifier, the context will save the new instance on commit(). Otherwise, even if some attributes of the merged instance are changed as a result of copying the state of the passed instance, the merged instance will not be committed. Such modifications are considered as a result of loading more fresh state from the database.
    WARNING: use the returned value because it is always a different object instance. The only case when you get the same instance is if the input was previously returned from the same context as a result of find(Class, Object) or merge().
    
    Parameters:
    
    entity - instance to merge
    
    options - merge options
    
    Returns:
    
    the instance which is tracked by the context
  - merge
```
@CheckReturnValue
<T> T merge(T entity)
```
    Same as merge(Object, MergeOptions) with default options.
  - merge
```
@CheckReturnValue
io.jmix.core.EntitySet merge(java.util.Collection entities,
                                               MergeOptions options)
```
    Merge the given entities into the context. The whole object graph for each element of the collection with all references will be merged.
    Same as merge(Object) but for a collection of instances.
    
    Returns:
    
    set of instances tracked by the context
  - merge
```
@CheckReturnValue
io.jmix.core.EntitySet merge(java.util.Collection entities)
```
    Merge the given entities into the context. The whole object graph for each element of the collection with all references will be merged.
    Same as merge(Object, MergeOptions) but for a collection of instances.
    
    Returns:
    
    set of instances tracked by the context
  - remove
```
void remove(java.lang.Object entity)
```
    Removes the entity from the context and registers it as deleted. The entity will be removed from the data store upon subsequent call to commit().
    If the given entity is not in the context, nothing happens.
  - evict
```
void evict(java.lang.Object entity)
```
    Removes the entity from the context so the context stops tracking it.
    If the given entity is not in the context, nothing happens.
  - evictModified
```
void evictModified()
```
    Clears the lists of created/modified/deleted entities and evicts these entities.
  - clear
```
void clear()
```
    Evicts all tracked entities.
    
    See Also:
    
    evict(Object)
  - create
```
<T> T create(java.lang.Class<T> entityClass)
```
    Creates an entity instance and merges it into the context.
    Same as:
```
 Foo foo = dataContext.merge(metadata.create(Foo.class));
 
```
    Parameters:
    
    entityClass - entity class
    
    Returns:
    
    a new instance which is tracked by the context
  - hasChanges
```
boolean hasChanges()
```
    Returns true if the context has detected changes in the tracked entities.
  - isModified
```
boolean isModified(java.lang.Object entity)
```
    Returns true if the context has detected changes in the given entity.
  - setModified
```
void setModified(java.lang.Object entity,
                 boolean modified)
```
    Registers or unregisters the given entity as modified.
    
    Parameters:
    
    entity - entity instance which is already merged into the context
    
    modified - true to register or false to unregister
  - getModified
```
java.util.Set<java.lang.Object> getModified()
```
    Returns an immutable set of entities registered as modified.
  - isRemoved
```
boolean isRemoved(java.lang.Object entity)
```
    Returns true if the context has registered removal of the given entity.
  - getRemoved
```
java.util.Set<java.lang.Object> getRemoved()
```
    Returns an immutable set of entities registered for removal.
  - commit
```
io.jmix.core.EntitySet commit()
```
    Commits changed and removed instances to the middleware. After successful commit, the context contains updated instances returned from the middleware.
    
    Returns:
    
    set of committed and merged back to the context instances. Does not contain removed instances.
    
    See Also:
    
    setParent(DataContext)
  - getParent
```
@Nullable
DataContext getParent()
```
    Returns a parent context, if any. If the parent context is set, commit() method merges the changed instances to it instead of sending to the middleware.
  - setParent
```
void setParent(DataContext parentContext)
```
    Sets the parent context. If the parent context is set, commit() method merges the changed instances to it instead of sending to the middleware.
  - addChangeListener
```
io.jmix.core.common.event.Subscription addChangeListener(java.util.function.Consumer<DataContext.ChangeEvent> listener)
```
    Adds a listener to DataContext.ChangeEvent.
  - addPreCommitListener
```
io.jmix.core.common.event.Subscription addPreCommitListener(java.util.function.Consumer<DataContext.PreCommitEvent> listener)
```
    Adds a listener to DataContext.PreCommitEvent.
    You can also add an event listener declaratively using a controller method annotated with Subscribe:
```
    @Subscribe(target = Target.DATA_CONTEXT)
    protected void onPreCommit(DataContext.PreCommitEvent event) {
       // handle event here
    }
 
```
    Parameters:
    
    listener - listener
    
    Returns:
    
    subscription
  - addPostCommitListener
```
io.jmix.core.common.event.Subscription addPostCommitListener(java.util.function.Consumer<DataContext.PostCommitEvent> listener)
```
    Adds a listener to DataContext.PostCommitEvent.
    You can also add an event listener declaratively using a controller method annotated with Subscribe:
```
    @Subscribe(target = Target.DATA_CONTEXT)
    protected void onPostCommit(DataContext.PostCommitEvent event) {
       // handle event here
    }
 
```
    Parameters:
    
    listener - listener
    
    Returns:
    
    subscription
  - getCommitDelegate
```
@Nullable
java.util.function.Function<io.jmix.core.SaveContext,java.util.Set<java.lang.Object>> getCommitDelegate()
```
    Returns a function which will be used to commit data instead of standard implementation.
  - setCommitDelegate
```
void setCommitDelegate(java.util.function.Function<io.jmix.core.SaveContext,java.util.Set<java.lang.Object>> delegate)
```
    Sets a function which will be used to commit data instead of standard implementation.

Interface DataContext

Nested Class Summary

Method Summary

Method Detail

find

find

contains

merge

merge

merge

merge

remove

evict

evictModified

clear

create

hasChanges

isModified

setModified

getModified

isRemoved

getRemoved

commit

getParent

setParent

addChangeListener

addPreCommitListener

addPostCommitListener

getCommitDelegate

setCommitDelegate