Author: painter
Date: Fri May 7 14:25:51 2021
New Revision: 1889631
URL: http://svn.apache.org/viewvc?rev=1889631&view=rev
Log:
Adding AvgHelper which works similarly to the CountHelper util for providing extra criteria to the Avg function
Added:
db/torque/trunk/torque-runtime/src/main/java/org/apache/torque/util/AvgHelper.java
Added: db/torque/trunk/torque-runtime/src/main/java/org/apache/torque/util/AvgHelper.java
URL: http://svn.apache.org/viewvc/db/torque/trunk/torque-runtime/src/main/java/org/apache/torque/util/AvgHelper.java?rev=1889631&view=auto
==============================================================================
--- db/torque/trunk/torque-runtime/src/main/java/org/apache/torque/util/AvgHelper.java (added)
+++ db/torque/trunk/torque-runtime/src/main/java/org/apache/torque/util/AvgHelper.java Fri May 7 14:25:51 2021
@@ -0,0 +1,162 @@
+package org.apache.torque.util;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * 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
+ * "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.
+ */
+
+/**
+ * This is a utility class which eases getting the
+ * average of a dataset column with criteria
+ *
+ * @author <a href="mailto:[email protected]">Jeffery Painter</a>
+ * @author <a href="mailto:[email protected]">Martin Goulet</a>
+ * @author <a href="mailto:[email protected]">Eric Lambert</a>
+ * @author <a href="mailto:[email protected]">Sebastien Paquette</a>
+ * @author <a href="mailto:[email protected]">Thomas Fischer</a>
+ * @version $Id$
+ */
+
+
+import java.math.BigDecimal;
+import java.sql.Connection;
+import java.util.List;
+
+import org.apache.torque.Column;
+import org.apache.torque.ColumnImpl;
+import org.apache.torque.Torque;
+import org.apache.torque.TorqueException;
+import org.apache.torque.criteria.Criteria;
+import org.apache.torque.criteria.SqlEnum;
+import org.apache.torque.map.TableMap;
+import org.apache.torque.om.mapper.BigDecimalMapper;
+import org.apache.torque.util.functions.Avg;
+
+/**
+ * Get's the average of a column with entries matching the provided criteria.
+ *
+ * This works similarly to the CountHelper when you need to provide
+ * additional selection criteria to compute an average.
+ *
+ * For example, limiting the average of a column in a table to a specific user.
+ */
+public class AvgHelper
+{
+
+ /**
+ * Returns the average of a column in a query.
+ *
+ * @param c Criteria to get the count for.
+ * @param columnName Name of database Column which is counted. Preferably,
+ * use the primary key here.
+ * @return average of the column matching the query provided
+ * @throws TorqueException if the query could not be executed
+ */
+ public BigDecimal avg(final Criteria c, final String columnName)
+ throws TorqueException
+ {
+ return avg(c, null, columnName, null);
+ }
+
+ /**
+ * Returns the average of a column in a query.
+ *
+ * @param c Criteria to get the count for.
+ * @param columnName Name of database Column which is averaged.
+ *
+ * @return average of the column matching the query provided
+ * @throws TorqueException if the query could not be executed
+ */
+ public BigDecimal avg(final Criteria c, final Column column)
+ throws TorqueException
+ {
+ return avg(c, column.getSqlExpression());
+ }
+
+ /**
+ * Returns the average of a column in a query.
+ *
+ * @param c Criteria to get the count for.
+ * @param conn Connection to use
+ * @param columnName Name of database Column which is averaged.
+ * @return average of the column matching the query provided
+ * @throws TorqueException if the query could not be executed
+ */
+ public BigDecimal avg(
+ final Criteria c,
+ final Connection conn,
+ final Column column)
+ throws TorqueException
+ {
+ return avg(c, conn, column.getSqlExpression(), null);
+ }
+
+
+ /**
+ * Returns the average of a column in a query.
+ *
+ * @param c Criteria to get the count for.
+ * @param conn Connection to use
+ * @param columnName Name of database Column which is averaged.
+ * @param tableMap the table to count the columns in, or null to determine
+ * the table automatically from the criteria.
+ *
+ * @return average of the column matching the query provided
+ *
+ * @throws TorqueException if the query could not be executed.
+ */
+ public BigDecimal avg(
+ final Criteria c,
+ final Connection conn,
+ final String columnName,
+ final TableMap tableMap)
+ throws TorqueException
+ {
+ /* Clear the select columns. */
+ c.getSelectColumns().clear();
+ c.getOrderByColumns().clear();
+ c.getGroupByColumns().clear();
+
+ UniqueList<String> criteriaSelectModifiers
+ = c.getSelectModifiers();
+
+ boolean distinct = false;
+ if (criteriaSelectModifiers != null
+ && criteriaSelectModifiers.size() > 0
+ && criteriaSelectModifiers.contains(SqlEnum.DISTINCT.toString()))
+ {
+ criteriaSelectModifiers.remove(SqlEnum.DISTINCT.toString());
+ distinct = true;
+ }
+
+ c.addSelectColumn(new Avg(new ColumnImpl(columnName), distinct));
+
+ String databaseName = (c.getDbName() == null)
+ ? Torque.getDefaultDB()
+ : c.getDbName();
+
+ BasePeerImpl<BigDecimal> peer = new BasePeerImpl<>(
+ new BigDecimalMapper(),
+ tableMap, databaseName);
+
+ List<BigDecimal> result = (conn == null)
+ ? peer.doSelect(c)
+ : peer.doSelect(c, conn);
+
+ return result.get(0);
+ }
+}
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