imp: Factory to create JdbcTemplate (#2518)

Author: sdelamo

data-spring-jdbc/src/main/java/io/micronaut/data/spring/jdbc/JdbcTemplateFactory.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2017-2023 original 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
+ *
+ * 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.
+ */
+package io.micronaut.data.spring.jdbc;
+
+import io.micronaut.context.annotation.EachBean;
+import io.micronaut.context.annotation.Factory;
+import io.micronaut.core.annotation.Internal;
+import io.micronaut.data.connection.jdbc.advice.DelegatingDataSource;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import javax.sql.DataSource;
+
+/**
+ * Factory for creating {@link JdbcTemplate} instances for each bean of type {@link DataSource}.
+ */
+@Internal
+@Factory
+class JdbcTemplateFactory {
+    /**
+     *
+     * @param dataSource Data Source
+     * @return JdbcTemplate
+     */
+    @EachBean(DataSource.class)
+    JdbcTemplate createJdbcTemplate(DataSource dataSource) {
+        return new JdbcTemplate(DelegatingDataSource.unwrapDataSource(dataSource));
+    }
+}

doc-examples/jdbc-spring-template-example-groovy/src/main/groovy/example/AbstractBookRepository.groovy

@@ -18,15 +18,15 @@ import javax.sql.DataSource
 @JdbcRepository(dialect = Dialect.H2)
 abstract class AbstractBookRepository implements CrudRepository<@Valid Book, @NotNull Long> {
 
-    private final JdbcTemplate jdbcTemplate; //<2>
+    private final JdbcTemplate jdbcTemplate
 
-    AbstractBookRepository(DataSource dataSource) { // <1>
-        this.jdbcTemplate = new JdbcTemplate(DelegatingDataSource.unwrapDataSource(dataSource)); //<2>
+    AbstractBookRepository(JdbcTemplate jdbcTemplate) { // <1>
+        this.jdbcTemplate = jdbcTemplate
     }
 
     @Transactional
     List<Book> findByTitle(@NonNull @NotNull String title) {
-        return jdbcTemplate.queryForList('SELECT * FROM Book AS book WHERE book.title = ?', title) // <3>
+        return jdbcTemplate.queryForList('SELECT * FROM Book AS book WHERE book.title = ?', title) // <2>
             .collect(m -> new Book(m.id as Long, m.title as String, m.pages as Integer))
     }
 }

doc-examples/jdbc-spring-template-example-java/src/main/java/example/AbstractBookRepository.java

@@ -2,7 +2,6 @@
 
 import io.micronaut.context.annotation.Requires;
 import io.micronaut.core.annotation.NonNull;
-import io.micronaut.data.connection.jdbc.advice.DelegatingDataSource;
 import io.micronaut.data.jdbc.annotation.JdbcRepository;
 import io.micronaut.data.model.query.builder.sql.Dialect;
 import io.micronaut.data.repository.CrudRepository;
@@ -19,15 +18,15 @@
 @JdbcRepository(dialect = Dialect.H2)
 public abstract class AbstractBookRepository implements CrudRepository<@Valid Book, @NotNull Long> {
 
-    private final JdbcTemplate jdbcTemplate; //<2>
+    private final JdbcTemplate jdbcTemplate;
 
-    public AbstractBookRepository(DataSource dataSource) { // <1>
-        this.jdbcTemplate = new JdbcTemplate(DelegatingDataSource.unwrapDataSource(dataSource)); //<2>
+    public AbstractBookRepository(JdbcTemplate jdbcTemplate) { // <1>
+        this.jdbcTemplate = jdbcTemplate;
     }
 
     @Transactional
     public List<Book> findByTitle(@NonNull @NotNull String title) {
-        return jdbcTemplate.queryForList("SELECT * FROM Book AS book WHERE book.title = ?", title) // <3>
+        return jdbcTemplate.queryForList("SELECT * FROM Book AS book WHERE book.title = ?", title) // <2>
             .stream()
             .map(m -> new Book((Long) m.get("id"), (String) m.get("title"), (Integer) m.get("pages")))
             .toList();

doc-examples/jdbc-spring-template-example-kotlin/src/main/kotlin/example/AbstractBookRepository.kt

@@ -13,13 +13,11 @@ import org.springframework.jdbc.core.JdbcTemplate
 @Requires(property = "spec.name", value = "BookRepositoryTest") // tag::clazz[]
 // tag::clazz[]
 @JdbcRepository(dialect = Dialect.H2)
-abstract class AbstractBookRepository(dataSource: DataSource) : CrudRepository<@Valid Book, Long> { // <1>
-
-    private val jdbcTemplate: JdbcTemplate = JdbcTemplate(DelegatingDataSource.unwrapDataSource(dataSource)) //<2>
+abstract class AbstractBookRepository(val jdbcTemplate: JdbcTemplate) : CrudRepository<@Valid Book, Long> {  //<1>
 
     @Transactional
     open fun findByTitle(title: String) = jdbcTemplate
-        .queryForList("SELECT * FROM Book AS book WHERE book.title = ?", title) // <3>
+        .queryForList("SELECT * FROM Book AS book WHERE book.title = ?", title) // <2>
         .map { m -> Book(m["id"] as Long, m["title"] as String, m["pages"] as Int) }
 }
 // end::clazz[]

src/main/docs/guide/dbc/dbcRepositories.adoc

@@ -46,9 +46,8 @@ The following code illustrates an example that integrates a `JdbcTemplate` insta
 
 snippet::example.AbstractBookRepository[project-base="doc-examples/jdbc-spring-template-example",source="main",tags="clazz"]
 
-<1> Inject the `java.sql.DataSource` configured by the application.
-<2> Instantiate a `JdbcTemplate` object using the injected `DataSource`.
-<3> Now the `JdbcTemplate` API can be used to implement repository methods.
+<1> Inject the `org.springframework.jdbc.core.JdbcTemplate` configured by the application.
+<2> Now the `JdbcTemplate` API can be used to implement repository methods.
 
 In addition, the transaction manager for Spring JDBC needs to be set in application configuration.