com.google.appengine.api.datastore
Class PreGetContext
- java.lang.Object
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- com.google.appengine.api.datastore.PreGetContext
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- All Implemented Interfaces:
- CallbackContext<Key>
public final class PreGetContext extends java.lang.Object
ConcreteCallbackContext
implementation that is specific to intercepted get() operations. Methods annotated withPreGet
that receive instances of this class may modify the result of the get() operation by callingsetResultForCurrentElement(Entity)
. Keys that receive results via this method will not be fetched from the datastore. This is an effective way to inject cached results.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method and Description T
getCurrentElement()
int
getCurrentIndex()
Transaction
getCurrentTransaction()
java.util.List<T>
getElements()
void
setResultForCurrentElement(Entity entity)
Set theEntity
that will be associated with theKey
returned bygetCurrentElement()
in the result of the get() operation.java.lang.String
toString()
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Method Detail
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setResultForCurrentElement
public void setResultForCurrentElement(Entity entity)
Set theEntity
that will be associated with theKey
returned bygetCurrentElement()
in the result of the get() operation. This will prevent the get() operation from fetching the Entity from the datastore. This is an effective way to inject cached results.- Parameters:
entity
- The entity to provide as the result for the current element.- Throws:
java.lang.IllegalArgumentException
- If the key of the provided entity is not equal to the key returned bygetCurrentElement()
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getElements
public java.util.List<T> getElements()
- Specified by:
getElements
in interfaceCallbackContext<T>
- Returns:
- An unmodifiable view of the elements involved in the operation that triggered the callback..
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getCurrentTransaction
public Transaction getCurrentTransaction()
- Specified by:
getCurrentTransaction
in interfaceCallbackContext<T>
- Returns:
- The current transaction, or
null
if there is no current transaction.
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getCurrentIndex
public int getCurrentIndex()
- Specified by:
getCurrentIndex
in interfaceCallbackContext<T>
- Returns:
- The index in the result of
CallbackContext.getElements()
of the element for which the callback has been invoked.
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getCurrentElement
public T getCurrentElement()
- Specified by:
getCurrentElement
in interfaceCallbackContext<T>
- Returns:
- The element for which the callback has been invoked. Shortcut for
getElements().getCurrentIndex()
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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