org.apache.openjpa.jdbc.kernel.exps.NullableAggregateUnaryOp Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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*/
package org.apache.openjpa.jdbc.kernel.exps;
/**
* OPENJPA-1794
* An aggregate unary operation that can indicate whether a null value from the data store
* should be returned as null.
*/
public abstract class NullableAggregateUnaryOp extends UnaryOp {
private static final long serialVersionUID = 1L;
public NullableAggregateUnaryOp(Val val) {
super(val);
}
public NullableAggregateUnaryOp(Val val, boolean noParen) {
super(val, noParen);
}
@Override
protected boolean nullableValue(ExpContext ctx, ExpState state) {
// If this is a simple operator (no joins involved), check compatibility to determine
// whether 'null' should be returned for the aggregate operation
if (ctx != null && ctx.store != null && (state.joins == null || state.joins.isEmpty())) {
return ctx.store.getConfiguration().getCompatibilityInstance().getReturnNullOnEmptyAggregateResult();
}
return false;
}
}