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 nextBatch = preparedQuery.asQueryResultList(withLimit(20).cursor(decoded));
 

See Also:

Serialized Form

Method Summary

boolean	equals(java.lang.Object obj)
static Cursor	fromWebSafeString(java.lang.String encodedCursor) Decodes the given encoded cursor
int	hashCode()
Cursor	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

public Cursor reverse()

Returns:

a new cursor to the location in a query sorted in the reverse direction

See Also:

Query.reverse()

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

Parameters:

encodedCursor -

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