Package org.apache.cayenne.query

Interface QueryRouter

public interface QueryRouter

An interface used by Queries to route themselves to an appropriate QueryEngine. As of 1.2 QueryRouter only supports routing by DataMap.

Since:

1.2

Method Summary

Modifier and Type	Method	Description
QueryEngine	engineForDataMap(DataMap map)	Returns a QueryEngine that is configured to handle a given DataMap.
QueryEngine	engineForName(String name)	Returns a QueryEngine for a given name.
void	route(QueryEngine engine, Query query, Query substitutedQuery)	A callback method that allows a query to set its preferred engine during the routing phase.

Method Details

route

void route(QueryEngine engine,
 Query query,
 Query substitutedQuery)

A callback method that allows a query to set its preferred engine during the routing phase. It allows query to further customize its routing, e.g. it is possible to implement query chains that pass multiple queries for execution.

Parameters:

engine - engine to use for query execution

query - A query to execute.

substitutedQuery - a query that was substituted for "query". Results must be mapped back to substituted query.

engineForName

QueryEngine engineForName(String name)

Returns a QueryEngine for a given name. If the name is null, a default QueryEngine is returned. If there's no default engine, an exception is thrown.

Since:

4.0

engineForDataMap

QueryEngine engineForDataMap(DataMap map)

Returns a QueryEngine that is configured to handle a given DataMap.

Throws:

CayenneRuntimeException - if an engine can't be found.

NullPointerException - if a map parameter is null.