org.apache.cayenne.query.QueryChain Maven / Gradle / Ivy
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package org.apache.cayenne.query;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.configuration.ConfigurationNodeVisitor;
import org.apache.cayenne.map.DataMap;
import org.apache.cayenne.map.EntityResolver;
/**
* 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
*/
public class QueryChain implements Query {
protected Collection chain;
protected String name;
/**
* @since 3.1
*/
protected DataMap dataMap;
/**
* Creates an empty QueryChain.
*/
public QueryChain() {
}
/**
* Creates a new QueryChain out of an array of queries.
*/
public QueryChain(Query[] queries) {
if (queries != null && queries.length > 0) {
this.chain = new ArrayList(Arrays.asList(queries));
}
}
/**
* Creates a new QueryChain with a collection of Queries.
*/
public QueryChain(Collection extends Query> queries) {
if (queries != null && !queries.isEmpty()) {
this.chain = new ArrayList(queries);
}
}
/**
* @since 3.1
*/
public T acceptVisitor(ConfigurationNodeVisitor visitor) {
return visitor.visitQuery(this);
}
/**
* Adds a query to the chain.
*/
public void addQuery(Query query) {
if (chain == null) {
chain = new ArrayList();
}
chain.add(query);
}
/**
* Removes a query from the chain, returning true if the query was indeed present in
* the chain and was removed.
*/
public boolean removeQuery(Query query) {
return (chain != null) ? chain.remove(query) : false;
}
public boolean isEmpty() {
return chain == null || chain.isEmpty();
}
/**
* Delegates routing to each individual query in the chain. If there is no queries,
* this method does nothing.
*/
public void route(QueryRouter router, EntityResolver resolver, Query substitutedQuery) {
if (chain != null && !chain.isEmpty()) {
for (Query q : chain) {
q.route(router, resolver, substitutedQuery);
}
}
}
/**
* Throws an exception as execution should've been delegated to the queries contained
* in the chain.
*/
public SQLAction createSQLAction(SQLActionVisitor visitor) {
throw new CayenneRuntimeException("Chain doesn't support its own execution "
+ "and should've been split into separate queries during routing phase.");
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
/**
* @since 3.1
*/
public DataMap getDataMap() {
return dataMap;
}
/**
* @since 3.1
*/
public void setDataMap(DataMap dataMap) {
this.dataMap = dataMap;
}
/**
* Returns default metadata.
*/
public QueryMetadata getMetaData(EntityResolver resolver) {
QueryMetadataWrapper wrapper = new QueryMetadataWrapper(
DefaultQueryMetadata.defaultMetadata);
wrapper.override(QueryMetadata.FETCHING_DATA_ROWS_PROPERTY, Boolean.TRUE);
return wrapper;
}
}
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