jooq/jOOQ/src/main/java/org/jooq/impl/ArrayTableEmulation.java

103 lines
2.9 KiB
Java

/*
* Licensed 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
*
* https://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 "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Other licenses:
* -----------------------------------------------------------------------------
* Commercial licenses for this work are available. These replace the above
* ASL 2.0 and offer limited warranties, support, maintenance, and commercial
* database integrations.
*
* For more information, please visit: https://www.jooq.org/legal/licensing
*
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*
*/
package org.jooq.impl;
import static org.jooq.impl.DSL.falseCondition;
import static org.jooq.impl.DSL.one;
import static org.jooq.impl.DSL.row;
import static org.jooq.impl.DSL.select;
import static org.jooq.impl.DSL.val;
import static org.jooq.impl.DSL.values0;
import static org.jooq.impl.Names.N_COLUMN_VALUE;
import static org.jooq.impl.Tools.componentDataType;
import static org.jooq.impl.Tools.map;
import static org.jooq.impl.Tools.visitSubquery;
import org.jooq.Context;
import org.jooq.DataType;
import org.jooq.Name;
import org.jooq.QueryPart;
import org.jooq.Row;
import org.jooq.Select;
import org.jooq.impl.QOM.UTransient;
/**
* Essentially, this is the same as <code>ArrayTable</code>, except that it
* emulates unnested arrays using <code>UNION ALL</code>
*
* @author Lukas Eder
*/
final class ArrayTableEmulation
extends
AbstractQueryPart
implements
UTransient
{
private final Object[] array;
private final DataType<?> type;
private final Name fieldAlias;
ArrayTableEmulation(Object[] array, Name[] fieldAliases) {
if (Tools.isEmpty(fieldAliases))
this.fieldAlias = N_COLUMN_VALUE;
else if (fieldAliases.length == 1)
this.fieldAlias = fieldAliases[0];
else
throw new IllegalArgumentException("Array table emulations can only have a single field alias");
this.array = array;
this.type = componentDataType(array);
}
// -------------------------------------------------------------------------
// XXX: QueryPart API
// -------------------------------------------------------------------------
@Override
public final void accept(Context<?> ctx) {
visitSubquery(ctx,
array.length > 0
? values0(map(array, e -> row(val(e, type)), Row[]::new))
: select(one().as(fieldAlias)).select().where(falseCondition()),
SubqueryCharacteristics.DERIVED_TABLE,
true
);
}
}