Demonstrate Schema Generation in Spring Data Jdbc.

This provides the source examples for the upcoming blog post.

Closes #667

jdbc/howto/pom.xml

@@ -24,6 +24,7 @@
 		<module>caching</module>
 		<module>idgeneration</module>
 		<module>selectiveupdate</module>
+		<module>schema-generation</module>
 	</modules>
 
 </project>

jdbc/howto/schema-generation/.gitignore

@@ -0,0 +1 @@
+cs-*.yaml

jdbc/howto/schema-generation/README.adoc

@@ -0,0 +1,5 @@
+== Spring Data JDBC How To Generate the Database Schema.
+
+Spring Data JDBC offers an API to generate Liquibase Changesets from your domain model and optionally an existing database.
+
+This project demonstrates how to do this.

jdbc/howto/schema-generation/pom.xml

@@ -0,0 +1,33 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>spring-data-jdbc-how-to-schema-generation</artifactId>
+
+    <parent>
+        <groupId>org.springframework.data.examples</groupId>
+        <artifactId>spring-data-jdbc-how-to</artifactId>
+        <version>2.0.0.BUILD-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <name>Spring Data JDBC - How to do schema generation</name>
+    <description>Sample project for Spring Data JDBC demonstrating how it can be used to generate and update your
+        schema.
+    </description>
+    <url>https://projects.spring.io/spring-data-jdbc</url>
+    <inceptionYear>2023</inceptionYear>
+
+    <properties>
+        <spring-data-bom.version>2023.1.0-M2</spring-data-bom.version>
+    </properties>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>org.liquibase</groupId>
+            <artifactId>liquibase-core</artifactId>
+        </dependency>
+    </dependencies>
+
+</project>

jdbc/howto/schema-generation/src/main/java/example.springdata/jdbc/howto/caching/Minion.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2023 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
+ *
+ *      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 example.springdata.jdbc.howto.caching;
+
+import org.springframework.data.annotation.Id;
+import org.springframework.data.relational.core.mapping.Table;
+
+
+/**
+ * Entity we use as a fixture for demonstrating Schema Generation.
+ * See SchemaGenerationTest in the test directory for the interesting stuff.
+ *
+ * @author Jens Schauder
+ * @since 3.2
+ */
+@Table
+class Minion {
+
+	@Id
+	Long id;
+
+	@Name
+	String name;
+
+	Minion(String name) {
+		this.name = name;
+	}
+
+	public Long getId() {
+		return id;
+	}
+}

jdbc/howto/schema-generation/src/main/java/example.springdata/jdbc/howto/caching/Name.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2023 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
+ *
+ *      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 example.springdata.jdbc.howto.caching;
+
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Annotation to mark a property as a Name which should have a very specify database type.
+ *
+ * @author Jens Schauder
+ */
+@Varchar(20)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Name {
+}

jdbc/howto/schema-generation/src/main/java/example.springdata/jdbc/howto/caching/SchemaGenerationExampleApplication.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2023 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
+ *
+ *      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 example.springdata.jdbc.howto.caching;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cache.annotation.EnableCaching;
+
+/**
+ * Boot application that we use as a fixture for demonstrating Schema Generation.
+ * See SchemaGenerationTest in the test directory for the interesting stuff.
+ *
+ * @author Jens Schauder
+ * @since 3.2
+ */
+@EnableCaching
+@SpringBootApplication
+class SchemaGenerationExampleApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(SchemaGenerationExampleApplication.class, args);
+	}
+
+}

jdbc/howto/schema-generation/src/main/java/example.springdata/jdbc/howto/caching/Varchar.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2023 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
+ *
+ *      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 example.springdata.jdbc.howto.caching;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Marks a property as to be represented by a VARCHAR database type.
+ *
+ * @author Jens Schauder
+ */
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Varchar {
+
+	/**
+	 * the size of the varchar.
+	 */
+	int value();
+}

jdbc/howto/schema-generation/src/main/resources/application.properties

@@ -0,0 +1,2 @@
+# Disable Liquibase when you don't have changesets configured yet.
+# spring.liquibase.enabled=false

jdbc/howto/schema-generation/src/main/resources/db/changelog/db.changelog-master.yaml

@@ -0,0 +1,32 @@
+databaseChangeLog:
+- changeSet:
+    id: '1692725820135'
+    author: Spring Data Relational
+    objectQuotingStrategy: LEGACY
+    changes:
+    - createTable:
+        columns:
+        - column:
+            autoIncrement: true
+            constraints:
+              nullable: true
+              primaryKey: true
+            name: id
+            type: BIGINT
+        - column:
+              constraints:
+                  nullable: true
+              name: firstname
+              type: VARCHAR(255 BYTE)
+        - column:
+              constraints:
+                  nullable: true
+              name: lastname
+              type: VARCHAR(255 BYTE)
+        - column:
+              constraints:
+                  nullable: true
+              name: special
+              type: VARCHAR(255 BYTE)
+        tableName: minion
+

jdbc/howto/schema-generation/src/test/java/example/springdata/jdbc/howto/caching/SchemaGenerationTest.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright 2023 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
+ *
+ *      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 example.springdata.jdbc.howto.caching;
+
+import liquibase.database.Database;
+import liquibase.database.core.HsqlDatabase;
+import liquibase.database.jvm.JdbcConnection;
+import liquibase.exception.LiquibaseException;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.core.io.FileSystemResource;
+import org.springframework.data.jdbc.core.mapping.schema.DefaultSqlTypeMapping;
+import org.springframework.data.jdbc.core.mapping.schema.LiquibaseChangeSetWriter;
+import org.springframework.data.jdbc.core.mapping.schema.SqlTypeMapping;
+import org.springframework.data.relational.core.mapping.RelationalMappingContext;
+
+import javax.sql.DataSource;
+import java.io.File;
+import java.io.IOException;
+import java.sql.SQLException;
+import java.util.Collections;
+
+/**
+ * Example code demonstrating how to use the Schema Generation Feature.
+ *
+ * @author Jens Schauder
+ * @since 3.2
+ */
+@SpringBootTest
+class SchemaGenerationTest {
+
+	@Autowired
+	RelationalMappingContext context;
+
+	@Autowired
+	DataSource ds;
+
+	@Test
+	void minimumExample() throws IOException {
+
+		// the change set will get appended, so we delete any pre existing file.
+		new File("cs-minimum.yaml").delete();
+
+		context.setInitialEntitySet(Collections.singleton(Minion.class));
+		LiquibaseChangeSetWriter writer = new LiquibaseChangeSetWriter(context);
+
+		writer.writeChangeSet(new FileSystemResource("cs-minimum.yaml"));
+	}
+
+
+	@Test
+	void diffing() {
+
+		// the change set will get appended, so we delete any pre existing file.
+		new File("cs-diff.yaml").delete();
+
+		context.setInitialEntitySet(Collections.singleton(Minion.class));
+		LiquibaseChangeSetWriter writer = new LiquibaseChangeSetWriter(context);
+
+		// drop unused columns
+		writer.setDropColumnFilter((table, column) -> !column.equalsIgnoreCase("special"));
+
+		// for comparison with existing schema
+		try (Database db = new HsqlDatabase()) {
+
+			db.setConnection(new JdbcConnection(ds.getConnection()));
+
+			writer.writeChangeSet(new FileSystemResource("cs-diff.yaml"), db);
+
+		} catch (IOException | SQLException | LiquibaseException e) {
+			throw new RuntimeException("Changeset generation failed", e);
+		}
+	}
+
+	@Test
+	void customizingTypes() throws IOException {
+
+		// the change set will get appended, so we delete any pre existing file.
+		new File("cs-custom.yaml").delete();
+
+		context.setInitialEntitySet(Collections.singleton(Minion.class));
+		LiquibaseChangeSetWriter writer = new LiquibaseChangeSetWriter(context);
+
+		writer.setSqlTypeMapping(((SqlTypeMapping) property -> {
+			if (property.getName().equalsIgnoreCase("name")) {
+				return "VARCHAR(500)";
+			}
+			return null;
+		}).and(new DefaultSqlTypeMapping()));
+
+		writer.writeChangeSet(new FileSystemResource("cs-custom.yaml"));
+
+	}
+
+	@Test
+	void customizingTypesUsingAnnotations() throws IOException {
+
+		// the change set will get appended, so we delete any pre existing file.
+		new File("cs-annotation.yaml").delete();
+
+		context.setInitialEntitySet(Collections.singleton(Minion.class));
+		LiquibaseChangeSetWriter writer = new LiquibaseChangeSetWriter(context);
+
+		writer.setSqlTypeMapping(((SqlTypeMapping) property -> {
+
+			if (!property.getType().equals(String.class)) {
+				return null;
+			}
+
+			// findAnnotation will find meta annotations
+			Varchar varchar = property.findAnnotation(Varchar.class);
+			int value = varchar.value();
+
+			if (varchar == null) {
+				return null;
+			}
+			return "VARCHAR(" +
+					varchar.value() +
+					")";
+
+		}).and(new DefaultSqlTypeMapping()));
+
+		writer.writeChangeSet(new FileSystemResource("cs-annotation.yaml"));
+
+	}
+}