Merge pull request #255 from jeffgbutler/general-mapper

Add MyBatis Utility Mapper for Any Query

Author: jeffgbutler

CHANGELOG.md

@@ -13,6 +13,7 @@ GitHub milestone: [https://github.com/mybatis/mybatis-dynamic-sql/issues?q=miles
 ### Added
 
 - Added a callback capability to the "In" conditions that will be called before rendering when the conditions are empty. Also, removed the option that forced the library to render invalid SQL in that case. ([#241](https://github.com/mybatis/mybatis-dynamic-sql/pull/241))
+- Added a utility mapper for MyBatis that allows you to run any select query without having to predefine a result mapping. ([#255](https://github.com/mybatis/mybatis-dynamic-sql/pull/255))
 
 ## Release 1.2.0 - August 19, 2020
 

pom.xml

@@ -208,6 +208,12 @@
       <version>5.2.8.RELEASE</version>
       <scope>provided</scope>
     </dependency>
+    <dependency>
+      <groupId>org.mybatis</groupId>
+      <artifactId>mybatis</artifactId>
+      <version>3.5.5</version>
+      <scope>provided</scope>
+    </dependency>
 
     <dependency>
       <groupId>org.junit.jupiter</groupId>
@@ -233,12 +239,6 @@
       <version>3.17.2</version>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.mybatis</groupId>
-      <artifactId>mybatis</artifactId>
-      <version>3.5.5</version>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.mybatis</groupId>
       <artifactId>mybatis-spring</artifactId>

src/main/java/org/mybatis/dynamic/sql/util/mybatis3/GeneralMapper.java

@@ -0,0 +1,290 @@
+/*
+ *    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 org.mybatis.dynamic.sql.util.mybatis3;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import org.apache.ibatis.annotations.SelectProvider;
+import org.mybatis.dynamic.sql.select.render.SelectStatementProvider;
+import org.mybatis.dynamic.sql.util.SqlProviderAdapter;
+
+/**
+ * This is a general purpose MyBatis mapper. It allows you to execute select statements without having to
+ * write a custom {@link org.apache.ibatis.annotations.ResultMap} for each statement.
+ *
+ * <p>This mapper contains three types of methods:
+ * <ul>
+ *   <li>The selectOneMappedRow and selectManyMappedRows methods allow you to use select statements with
+ *     any number of columns. MyBatis will process the rows and return a Map of values, or a List of Maps.</li>
+ *   <li>The selectOne and selectMany methods also allow you to use select statements with any number of columns.
+ *   These methods also allow you to specify a function that will transform a Map of row values into a specific
+ *   object.</li>
+ *   <li>The other methods are for result sets with a single column. There are functions for many
+ *   data types (Integer, Long, String, etc.) There are also functions that return a single value, and Optional value,
+ *   or a List of values.</li>
+ * </ul>
+ *
+ * <p>This mapper can be injected as-is into a MyBatis configuration, or it can be extended with existing mappers.
+ *
+ * @author Jeff Butler
+ */
+public interface GeneralMapper {
+    /**
+     * Select a single row as a Map of values. The row may have any number of columns.
+     * The Map key will be the column name as returned from the
+     * database (may be aliased if an alias is specified in the select statement). Map entries will be
+     * of data types determined by the JDBC driver. MyBatis will call ResultSet.getObject() to retrieve
+     * values from the ResultSet. Reference your JDBC driver documentation to learn about type mappings
+     * for your specific database.
+     *
+     * @param selectStatement the select statement
+     * @return A Map containing the row values.
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Map<String, Object> selectOneMappedRow(SelectStatementProvider selectStatement);
+
+    /**
+     * Select a single row of values and then convert the values to a custom type. This is similar
+     * to the Spring JDBC template method of processing result sets. In this case, MyBatis will first extract
+     * the row values into a Map, and then a row mapper can retrieve values from the Map and use them
+     * to construct a custom object.
+     *
+     * <p>See {@link GeneralMapper#selectOneMappedRow(SelectStatementProvider)} for details about
+     * how MyBatis will construct the Map of values.
+     *
+     * @param selectStatement the select statement
+     * @param rowMapper a function that will convert a Map of row values to the desired data type
+     * @param <R> the datatype of the converted object
+     * @return the converted object
+     */
+    default <R> R selectOne(SelectStatementProvider selectStatement,
+                            Function<Map<String, Object>, R> rowMapper) {
+        return rowMapper.apply(selectOneMappedRow(selectStatement));
+    }
+
+    /**
+     * Select any number of rows and return a List of Maps containing row values (one Map for each row returned).
+     * The rows may have any number of columns.
+     * The Map key will be the column name as returned from the
+     * database (may be aliased if an alias is specified in the select statement). Map entries will be
+     * of data types determined by the JDBC driver. MyBatis will call ResultSet.getObject() to retrieve
+     * values from the ResultSet. Reference your JDBC driver documentation to learn about type mappings
+     * for your specific database.
+     *
+     * @param selectStatement the select statement
+     * @return A List of Maps containing the row values.
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    List<Map<String, Object>> selectManyMappedRows(SelectStatementProvider selectStatement);
+
+    /**
+     * Select any number of rows and then convert the values to a custom type. This is similar to the
+     * Spring JDBC template method of processing result sets. In this case, MyBatis will first extract the
+     * row values into a List of Map, and them a row mapper can retrieve values from the Map and use them
+     * to construct a custom object for each row.
+     *
+     * @param selectStatement the select statement
+     * @param rowMapper a function that will convert a Map of row values to the desired data type
+     * @param <R> the datatype of the converted object
+     * @return the List of converted objects
+     */
+    default <R> List<R> selectMany(SelectStatementProvider selectStatement,
+                                   Function<Map<String, Object>, R> rowMapper) {
+        return selectManyMappedRows(selectStatement).stream()
+                .map(rowMapper)
+                .collect(Collectors.toList());
+    }
+
+    /**
+     * Retrieve a single {@link java.math.BigDecimal} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getBigDecimal() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. May be null if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    BigDecimal selectOneBigDecimal(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.math.BigDecimal} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getBigDecimal() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. The Optional will be empty if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Optional<BigDecimal> selectOptionalBigDecimal(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a List of {@link java.math.BigDecimal} from a result set. The result set must have
+     * only one column, but can have any number of rows. The column must be retrievable from the result set
+     * via the ResultSet.getBigDecimal() method.
+     *
+     * @param selectStatement the select statement
+     * @return the list of extracted values. Any value may be null if a column in the result set is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    List<BigDecimal> selectManyBigDecimals(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.Double} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getDouble() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. May be null if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Double selectOneDouble(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.Double} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getDouble() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. The Optional will be empty if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Optional<Double> selectOptionalDouble(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a List of {@link java.lang.Double} from a result set. The result set must have
+     * only one column, but can have any number of rows. The column must be retrievable from the result set
+     * via the ResultSet.getDouble() method.
+     *
+     * @param selectStatement the select statement
+     * @return the list of extracted values. Any value may be null if a column in the result set is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    List<Double> selectManyDoubles(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.Integer} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getInt() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. May be null if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Integer selectOneInteger(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.Integer} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getInt() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. The Optional will be empty if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Optional<Integer> selectOptionalInteger(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a List of {@link java.lang.Integer} from a result set. The result set must have
+     * only one column, but can have any number of rows. The column must be retrievable from the result set
+     * via the ResultSet.getInt() method.
+     *
+     * @param selectStatement the select statement
+     * @return the list of extracted values. Any value may be null if a column in the result set is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    List<Integer> selectManyIntegers(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.Long} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getLong() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. May be null if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Long selectOneLong(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.Long} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getLong() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. The Optional will be empty if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Optional<Long> selectOptionalLong(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a List of {@link java.lang.Long} from a result set. The result set must have
+     * only one column, but can have any number of rows. The column must be retrievable from the result set
+     * via the ResultSet.getLong() method.
+     *
+     * @param selectStatement the select statement
+     * @return the list of extracted values. Any value may be null if a column in the result set is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    List<Long> selectManyLongs(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.String} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getString() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. May be null if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    String selectOneString(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a single {@link java.lang.String} from a result set. The result set must have
+     * only one column and one or zero rows. The column must be retrievable from the result set
+     * via the ResultSet.getString() method.
+     *
+     * @param selectStatement the select statement
+     * @return the extracted value. The Optional will be empty if zero rows are returned, or if the returned
+     *     column is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    Optional<String> selectOptionalString(SelectStatementProvider selectStatement);
+
+    /**
+     * Retrieve a List of {@link java.lang.String} from a result set. The result set must have
+     * only one column, but can have any number of rows. The column must be retrievable from the result set
+     * via the ResultSet.getString() method.
+     *
+     * @param selectStatement the select statement
+     * @return the list of extracted values. Any value may be null if a column in the result set is null
+     */
+    @SelectProvider(type = SqlProviderAdapter.class, method = "select")
+    List<String> selectManyStrings(SelectStatementProvider selectStatement);
+}