#550 - ENH: Add generated file warning to DB migration XML files

src/main/java/com/avaje/ebean/config/DbMigrationConfig.java

@@ -88,6 +88,8 @@ public class DbMigrationConfig {
 
   protected String modelSuffix = ".model.xml";
 
+  protected boolean includeGeneratedFileComment;
+
   /**
    * Return the DB platform to generate migration DDL for.
    *
@@ -236,6 +238,20 @@ public class DbMigrationConfig {
     this.rollbackSuffix = rollbackSuffix;
   }
 
+  /**
+   * Return true if the generated file comment should be included.
+   */
+  public boolean isIncludeGeneratedFileComment() {
+    return includeGeneratedFileComment;
+  }
+
+  /**
+   * Set to true if the generated file comment should be included.
+   */
+  public void setIncludeGeneratedFileComment(boolean includeGeneratedFileComment) {
+    this.includeGeneratedFileComment = includeGeneratedFileComment;
+  }
+
   /**
    * Set the migration version.
    * <p>
@@ -281,6 +297,7 @@ public class DbMigrationConfig {
     dropSuffix = properties.get("migration.dropSuffix", dropSuffix);
     rollbackSuffix = properties.get("migration.rollbackSuffix", rollbackSuffix);
     modelSuffix = properties.get("migration.modelSuffix", modelSuffix);
+    includeGeneratedFileComment = properties.getBoolean("migration.includeGeneratedFileComment", includeGeneratedFileComment);
 
     platform = properties.getEnum(DbPlatformName.class, "migration.platform", platform);
     suppressRollback = properties.getBoolean("migration.suppressRollback", suppressRollback);

src/main/java/com/avaje/ebean/dbmigration/DbMigration.java

@@ -59,6 +59,8 @@ public class DbMigration {
 
   private static final String initialVersion = "1.0";
 
+  private static final String GENERATED_COMMENT = "THIS IS A GENERATED FILE - DO NOT MODIFY";
+
   /**
    * Set to true if DbMigration run with online EbeanServer instance.
    */
@@ -304,7 +306,8 @@ public class DbMigration {
     if (file.exists()) {
       return false;
     }
-    MigrationXmlWriter xmlWriter = new MigrationXmlWriter();
+    String comment = migrationConfig.isIncludeGeneratedFileComment() ? GENERATED_COMMENT : null;
+    MigrationXmlWriter xmlWriter = new MigrationXmlWriter(comment);
     xmlWriter.write(dbMigration, file);
     return true;
   }

src/main/java/com/avaje/ebean/dbmigration/migrationreader/MigrationXmlWriter.java

@@ -7,22 +7,46 @@ import javax.xml.bind.JAXBContext;
 import javax.xml.bind.JAXBException;
 import javax.xml.bind.Marshaller;
 import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
 
 /**
  * Simple writer for output of the Migration/ChangeSet as an XML document.
  */
 public class MigrationXmlWriter {
 
+  private final String comment;
+
+  public MigrationXmlWriter(String comment) {
+    this.comment = comment;
+  }
+
   /**
    * Write a Migration to a file as an xml document to the file.
    */
   public void write(Migration migration, File file) {
 
     try {
+
+      FileWriter writer = new FileWriter(file);
+      writer.write("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n");
+      if (comment != null) {
+        writer.write("<!-- ");
+        writer.write(comment);
+        writer.write(" -->\n");
+      }
+
       JAXBContext jaxbContext = JAXBContext.newInstance(Migration.class);
       Marshaller marshaller = jaxbContext.createMarshaller();
-      marshaller.setProperty( Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
-      marshaller.marshal(migration, file);
+      marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
+      marshaller.setProperty(Marshaller.JAXB_FRAGMENT, Boolean.TRUE);
+
+      marshaller.marshal(migration, writer);
+
+      writer.close();
+
+    } catch (IOException e) {
+      throw new RuntimeException(e);
 
     } catch (JAXBException e) {
       throw new RuntimeException(e);

src/test/java/com/avaje/ebean/dbmigration/migrationreader/MigrationXmlWriterTest.java

@@ -5,16 +5,30 @@ import org.junit.Test;
 
 import java.io.File;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 public class MigrationXmlWriterTest {
 
   @Test
   public void testReadWrite() throws Exception {
 
     Migration migration = MigrationXmlReader.read("/container/test-create-table.xml");
+    assertThat(migration.getChangeSet()).hasSize(1);
+    assertThat(migration.getChangeSet().get(0).getChangeSetChildren()).hasSize(3);
 
     File temp = File.createTempFile("migrationWrite",".xml");
-    MigrationXmlWriter writer = new MigrationXmlWriter();
-    writer.write(migration, temp);
+    new MigrationXmlWriter("THIS IS A GENERATED FILE - DO NOT MODIFY").write(migration, temp);
 
+    Migration migrationRead = MigrationXmlReader.read(temp);
+    assertThat(migrationRead.getChangeSet()).hasSize(1);
+    assertThat(migrationRead.getChangeSet().get(0).getChangeSetChildren()).hasSize(3);
+
+    temp = File.createTempFile("migrationWrite",".xml");
+    new MigrationXmlWriter(null).write(migration, temp);
+
+    Migration migrationRead2 = MigrationXmlReader.read(temp);
+
+    assertThat(migrationRead2.getChangeSet()).hasSize(1);
+    assertThat(migrationRead.getChangeSet().get(0).getChangeSetChildren()).hasSize(3);
   }
 }