org.apache.cayenne.query
Class QueryChain

java.lang.Object
  extended by org.apache.cayenne.query.QueryChain
All Implemented Interfaces:
Serializable, Query

public class QueryChain
extends Object
implements Query

A Query decorator for a collection of other queries. Note that QueryChain will always return DataRows (that is if it returns data), as it has no way of knowing how to convert the results to objects.

Since:
1.2
See Also:
Serialized Form

Field Summary
protected  Collection<Query> chain
           
protected  String name
           
 
Constructor Summary
QueryChain()
          Creates an empty QueryChain.
QueryChain(Collection<Query> queries)
          Creates a new QueryChain with a collection of Queries.
QueryChain(Query[] queries)
          Creates a new QueryChain out of an array of queries.
 
Method Summary
 void addQuery(Query query)
          Adds a query to the chain.
 SQLAction createSQLAction(SQLActionVisitor visitor)
          Throws an exception as execution should've been delegated to the queries contained in the chain.
 QueryMetadata getMetaData(EntityResolver resolver)
          Returns default metadata.
 String getName()
          Returns a symbolic name of the query.
 boolean isEmpty()
           
 boolean removeQuery(Query query)
          Removes a query from the chain, returning true if the query was indeed present in the chain and was removed.
 void route(QueryRouter router, EntityResolver resolver, Query substitutedQuery)
          Delegates routing to each individual query in the chain.
 void setName(String name)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

chain

protected Collection<Query> chain

name

protected String name
Constructor Detail

QueryChain

public QueryChain()
Creates an empty QueryChain.


QueryChain

public QueryChain(Query[] queries)
Creates a new QueryChain out of an array of queries.


QueryChain

public QueryChain(Collection<Query> queries)
Creates a new QueryChain with a collection of Queries.

Method Detail

addQuery

public void addQuery(Query query)
Adds a query to the chain.


removeQuery

public boolean removeQuery(Query query)
Removes a query from the chain, returning true if the query was indeed present in the chain and was removed.


isEmpty

public boolean isEmpty()

route

public void route(QueryRouter router,
                  EntityResolver resolver,
                  Query substitutedQuery)
Delegates routing to each individual query in the chain. If there is no queries, this method does nothing.

Specified by:
route in interface Query

createSQLAction

public SQLAction createSQLAction(SQLActionVisitor visitor)
Throws an exception as execution should've been delegated to the queries contained in the chain.

Specified by:
createSQLAction in interface Query

getName

public String getName()
Description copied from interface: Query
Returns a symbolic name of the query. The name may be used as a key to find queries stored in the DataMap. Some query implementors reuse the name as a QueryMetadata cache key. Generally the name can be null.

Specified by:
getName in interface Query

setName

public void setName(String name)

getMetaData

public QueryMetadata getMetaData(EntityResolver resolver)
Returns default metadata.

Specified by:
getMetaData in interface Query


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