Example Length Function

Author: jeffgbutler

src/test/java/examples/animal/data/AnimalDataTest.java

@@ -805,6 +805,26 @@ void testLikeUpperCase() {
         }
     }
 
+    @Test
+    void testLength() {
+        try (SqlSession sqlSession = sqlSessionFactory.openSession()) {
+            CommonSelectMapper mapper = sqlSession.getMapper(CommonSelectMapper.class);
+
+            SelectStatementProvider selectStatement = select(id, upper(animalName).as("animalname"), bodyWeight, brainWeight)
+                    .from(animalData)
+                    .where(Length.length(animalName), isGreaterThan(22))
+                    .orderBy(id)
+                    .build()
+                    .render(RenderingStrategies.MYBATIS3);
+
+            List<Map<String, Object>> animals = mapper.selectManyMappedRows(selectStatement);
+
+            assertThat(animals).hasSize(2);
+            assertThat(animals.get(0)).containsEntry("ANIMALNAME", "LESSER SHORT-TAILED SHREW");
+            assertThat(animals.get(1)).containsEntry("ANIMALNAME", "AFRICAN GIANT POUCHED RAT");
+        }
+    }
+
     @Test
     void testNumericConstant() {
         try (SqlSession sqlSession = sqlSessionFactory.openSession()) {

src/test/java/examples/animal/data/Length.java

@@ -0,0 +1,58 @@
+/*
+ *    Copyright 2016-2020 the original author or authors.
+ *
+ *    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
+ *
+ *       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.
+ */
+package examples.animal.data;
+
+import org.mybatis.dynamic.sql.BindableColumn;
+import org.mybatis.dynamic.sql.render.TableAliasCalculator;
+import org.mybatis.dynamic.sql.select.function.AbstractTypeConvertingFunction;
+
+import java.sql.JDBCType;
+import java.util.Optional;
+
+public class Length extends AbstractTypeConvertingFunction<Object, Integer, Length> {
+    private Length(BindableColumn<Object> column) {
+        super(column);
+    }
+
+    @Override
+    public Optional<JDBCType> jdbcType() {
+        return Optional.of(JDBCType.INTEGER);
+    }
+
+    @Override
+    public Optional<String> typeHandler() {
+        return Optional.empty();
+    }
+
+    @Override
+    public String renderWithTableAlias(TableAliasCalculator tableAliasCalculator) {
+        return "length(" //$NON-NLS-1$
+                + column.renderWithTableAlias(tableAliasCalculator)
+                + ")"; //$NON-NLS-1$
+    }
+
+    @Override
+    protected Length copy() {
+        return new Length(column);
+    }
+
+    public static Length length(BindableColumn<?> column) {
+        @SuppressWarnings("unchecked")
+        BindableColumn<Object> c = (BindableColumn<Object>) column;
+        return new Length(c);
+    }
+}
+