Package org.apache.cayenne

Interface QueryResponse

All Known Implementing Classes:
GenericResponse, IncrementalListResponse, ListResponse
public interface QueryResponse
Represents a result of query execution. It potentially contain a mix of update counts and lists of selected values. Provides API somewhat similar to java.util.Iterator or java.sql.ResultSet for scanning through the individual results.

An example of iterating through a response: 

 QueryResponse response = context.performGenericQuery(query);
 for (response.reset(); response.next();) {
     if (response.isList()) {
         List list = response.currentList();
         // ...
     }
     else {
         int[] updateCounts = response.currentUpdateCount();
         // ...
     }
 }

In case the structure of the result is known, and only a single list or an update count is expected, there is a simpler API to access them: 

 QueryResponse response = context.performGenericQuery(query);
 List list = response.firstList();
 int[] count = response.firstUpdateCount();
Since:
1.2

  • Method Summary

    Modifier and Type
    Method
    Description
    List<?>
    currentList()
    Returns a List under the current iterator position.
    int[]
    currentUpdateCount()
    Returns an update count under the current iterator position.
    List
    firstList()
    A utility method for quickly retrieving the first list in the response.
    int[]
    firstUpdateCount()
    A utility method for quickly retrieving the first update count from the response.
    boolean
    isList()
    Returns whether current iteration result is a list or an update count.
    boolean
    next()
    Rewinds response iterator to the next result, returning true if it is available.
    void
    reset()
    Restarts response iterator.
    int
    size()
    Returns a number of results in the response.

  • Method Details

    • size

      int size()
      Returns a number of results in the response.

    • isList

      boolean isList()
      Returns whether current iteration result is a list or an update count.

    • currentList

      List<?> currentList()
      Returns a List under the current iterator position. Use isList() to check the result type before calling this method.

    • currentUpdateCount

      int[] currentUpdateCount()
      Returns an update count under the current iterator position. Returned value is an int[] to accommodate batch queries. For a regular update result, the value will be an int[1]. Use isList() to check the result type before calling this method.

    • next

      boolean next()
      Rewinds response iterator to the next result, returning true if it is available.

    • reset

      void reset()
      Restarts response iterator.

    • firstList

      List firstList()
      A utility method for quickly retrieving the first list in the response. Returns null if the query has no lists. Note that this method resets current iterator to an undefined state.

    • firstUpdateCount

      int[] firstUpdateCount()
      A utility method for quickly retrieving the first update count from the response. Note that this method resets current iterator to an undefined state.