com.google.appengine.api.datastore

Class Cursor

java.lang.Object

com.google.appengine.api.datastore.Cursor

All Implemented Interfaces:

java.io.Serializable

public final class Cursor
extends java.lang.Object
implements java.io.Serializable

A cursor that represents a position in a query.

To resume a Query at the position defined by a Cursor, the Cursor must be present in the FetchOptions passed to a PreparedQuery identical to the one it was created from.

Cursors can be retrieved from PreparedQuery.asQueryResult* functions. A typical use case would be:

 Cursor originalCursor = preparedQuery.asQueryResultList(withLimit(20)).getCursor();
 String encodedCursor = original.toWebSafeString();
 

The encoded cursor can then be passed safely in a get or post arg of a web request and on another request the next batch of results can be retrieved with:

 Cursor decodedCursor = Cursor.fromWebSafeString(encodedCursor);
 List<Entity> nextBatch = preparedQuery.asQueryResultList(withLimit(20).cursor(decoded));
 

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object obj)
static Cursor	fromWebSafeString(java.lang.String encodedCursor) Decodes the given encoded cursor
int	hashCode()
Cursor	reverse() Deprecated. It is no longer necessary to call reverse() on cursors. A cursor returned by a query may also be used in the query returned by Query.reverse().
java.lang.String	toString()
java.lang.String	toWebSafeString() Encodes the current cursor as a web safe string that can later be decoded by fromWebSafeString(String)

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

reverse

@Deprecated
public Cursor reverse()

Deprecated. It is no longer necessary to call reverse() on cursors.

A cursor returned by a query may also be used in the query returned by Query.reverse().

Returns a cursor identical to this.

toWebSafeString

public java.lang.String toWebSafeString()

Encodes the current cursor as a web safe string that can later be decoded by fromWebSafeString(String)

fromWebSafeString

public static Cursor fromWebSafeString(java.lang.String encodedCursor)

Decodes the given encoded cursor

Returns:

the decoded cursor

Throws:

java.lang.IllegalArgumentException - if the provided string is not a valid encoded cursor

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object