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## org.apache.cayenne.query
Class QueryChain

    java.lang.Object
      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
Author:
  Andrus Adamchik
See Also:
  Serialized Form

Field Summary
`protected Collection` | `chain`
`protected String` | `name`

Constructor Summary
`QueryChain()` Creates an empty QueryChain.
`QueryChain(Collection 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 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 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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