#374 - Refactor to support generating multiple platform DDL for a single migration

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

@@ -16,11 +16,12 @@ import com.avaje.ebean.config.dbplatform.PostgresPlatform;
 import com.avaje.ebean.config.dbplatform.SQLitePlatform;
 import com.avaje.ebean.dbmigration.ddlgeneration.DdlWrite;
 import com.avaje.ebean.dbmigration.migration.Migration;
+import com.avaje.ebean.dbmigration.migrationreader.MigrationXmlWriter;
 import com.avaje.ebean.dbmigration.model.CurrentModel;
 import com.avaje.ebean.dbmigration.model.MConfiguration;
 import com.avaje.ebean.dbmigration.model.MigrationModel;
 import com.avaje.ebean.dbmigration.model.ModelContainer;
-import com.avaje.ebean.dbmigration.model.ModelDdlWriter;
+import com.avaje.ebean.dbmigration.model.PlatformDdlWriter;
 import com.avaje.ebean.dbmigration.model.ModelDiff;
 import com.avaje.ebeaninternal.api.SpiEbeanServer;
 import org.slf4j.Logger;
@@ -28,25 +29,29 @@ import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  *
  */
 public class DbMigration {
 
-  private static final Logger logger = LoggerFactory.getLogger(DbMigration.class);
+  protected static final Logger logger = LoggerFactory.getLogger(DbMigration.class);
 
-  private SpiEbeanServer server;
+  protected SpiEbeanServer server;
 
-  private DbMigrationConfig migrationConfig;
+  protected DbMigrationConfig migrationConfig;
 
-  private String pathToResources = "src/main/resources";
+  protected String pathToResources = "src/main/resources";
 
-  private DatabasePlatform databasePlatform;
+  protected DatabasePlatform databasePlatform;
 
-  private ServerConfig serverConfig;
+  protected List<Pair> platforms = new ArrayList<Pair>();
 
-  private DbConstraintNaming constraintNaming;
+  protected ServerConfig serverConfig;
+
+  protected DbConstraintNaming constraintNaming;
 
   public DbMigration() {
     DbOffline.asH2();
@@ -82,6 +87,16 @@ public class DbMigration {
     DbOffline.setPlatform(databasePlatform.getName());
   }
 
+  /**
+   * Add an additional platform to write the migration DDL.
+   */
+  public void addPlatform(DbPlatformName platform, String prefix) {
+    if (!prefix.endsWith("-")) {
+      prefix+="-";
+    }
+    platforms.add(new Pair(getPlatform(platform), prefix));
+  }
+
 
   public void runMigration() throws IOException {
 
@@ -102,35 +117,58 @@ public class DbMigration {
 
       ModelDiff diff = new ModelDiff(migrated);
       diff.compareTo(current);
+
+      if (diff.isEmpty()) {
+        logger.info("no changes detected - no migration written");
+        return;
+      }
+
+      // there were actually changes to write
       Migration dbMigration = diff.getMigration();
 
-      // writer needs the current model to provide table/column details for
-      // history ddl generation (triggers, history tables etc)
-      DdlWrite write = new DdlWrite(new MConfiguration(), currentModel.read());
+      File writePath = getWritePath();
+      logger.info("migration writing version {} to {}", nextMajorVersion, writePath.getAbsolutePath());
+      writeMigrationXml(dbMigration, writePath, nextMajorVersion);
 
-      ModelDdlWriter writer = new ModelDdlWriter(databasePlatform, serverConfig);
-      if (!writer.processMigration(dbMigration, write)) {
-        logger.info("no changes detected - no migration written");
-
-      } else {
-        // there were actually changes to write
-        File writePath = getWritePath();
-        logger.info("migration writing version {} to {}", nextMajorVersion, writePath.getAbsolutePath());
-        writer.writeMigration(writePath, nextMajorVersion);
+      if (databasePlatform != null) {
+        // writer needs the current model to provide table/column details for
+        // history ddl generation (triggers, history tables etc)
+        DdlWrite write = new DdlWrite(new MConfiguration(), currentModel.read());
+        PlatformDdlWriter writer = new PlatformDdlWriter(databasePlatform, serverConfig);
+        writer.processMigration(dbMigration, write, writePath, nextMajorVersion);
       }
 
+      writeExtraPlatformDdl(nextMajorVersion, currentModel, dbMigration, writePath);
+
     } finally {
       DbOffline.reset();
     }
   }
 
+  /**
+   * Write any extra platform ddl.
+   */
+  protected void writeExtraPlatformDdl(int nextMajorVersion, CurrentModel currentModel, Migration dbMigration, File writePath) throws IOException {
+
+    for (Pair pair : platforms) {
+      DdlWrite platformBuffer = new DdlWrite(new MConfiguration(), currentModel.read());
+
+      PlatformDdlWriter platformWriter = new PlatformDdlWriter(pair.platform, serverConfig, pair.prefix);
+      platformWriter.processMigration(dbMigration, platformBuffer, writePath, nextMajorVersion);
+    }
+  }
+
+  protected void writeMigrationXml(Migration dbMigration, File resourcePath, int migrationVersion) {
+    File file = new File(resourcePath, "v"+migrationVersion+".0.xml");
+
+    MigrationXmlWriter xmlWriter = new MigrationXmlWriter();
+    xmlWriter.write(dbMigration, file);
+  }
+
   protected void setDefaults() {
     if (server == null) {
       setServer(Ebean.getDefaultServer());
     }
-    if (databasePlatform == null) {
-      databasePlatform = server.getDatabasePlatform();
-    }
   }
 
   protected File getWritePath() {
@@ -172,4 +210,26 @@ public class DbMigration {
     }
   }
 
+  /**
+   * Holds a platform and prefix. Used to generate multiple platform specific DDL
+   * for a single migration.
+   */
+  public static class Pair {
+
+    /**
+     * The platform to generate the DDL for.
+     */
+    public final DatabasePlatform platform;
+
+    /**
+     * A prefix included into the file/resource names indicating the platform.
+     */
+    public final String prefix;
+
+    public Pair(DatabasePlatform platform, String prefix) {
+      this.platform = platform;
+      this.prefix = prefix;
+    }
+  }
+
 }

src/main/java/com/avaje/ebean/dbmigration/ddlgeneration/DdlWrite.java

@@ -81,17 +81,18 @@ public class DdlWrite {
   }
 
   /**
-   * Return true the drop buffer is empty.
+   * Return true if the apply rollback buffers are all empty.
    */
-  public boolean isDropEmpty() {
-    return drop.getBuffer().isEmpty();
+  public boolean isApplyRollbackEmpty() {
+    return rollback.getBuffer().isEmpty()
+        && rollbackForeignKeys.getBuffer().isEmpty();
   }
 
   /**
-   * Return true the drop history buffer is empty.
+   * Return true the drop buffers are empty.
    */
-  public boolean isDropHistoryEmpty() {
-    return dropHistory.getBuffer().isEmpty();
+  public boolean isDropEmpty() {
+    return drop.getBuffer().isEmpty() && dropHistory.getBuffer().isEmpty();
   }
 
   /**

src/main/java/com/avaje/ebean/dbmigration/model/ModelDdlWriter.java

@@ -1,140 +0,0 @@
-package com.avaje.ebean.dbmigration.model;
-
-import com.avaje.ebean.config.ServerConfig;
-import com.avaje.ebean.config.dbplatform.DatabasePlatform;
-import com.avaje.ebean.dbmigration.ddlgeneration.DdlHandler;
-import com.avaje.ebean.dbmigration.ddlgeneration.DdlWrite;
-import com.avaje.ebean.dbmigration.migration.ChangeSet;
-import com.avaje.ebean.dbmigration.migration.Migration;
-import com.avaje.ebean.dbmigration.migrationreader.MigrationXmlWriter;
-
-import java.io.File;
-import java.io.FileWriter;
-import java.io.IOException;
-import java.io.Writer;
-import java.util.List;
-
-/**
- */
-public class ModelDdlWriter {
-
-
-  private final ServerConfig serverConfig;
-
-  private final DatabasePlatform platform;
-
-  private Migration dbMigration;
-
-  private DdlWrite write;
-
-  int changeSetCount;
-
-  public ModelDdlWriter(DatabasePlatform platform, ServerConfig serverConfig) {
-    this.platform = platform;
-    this.serverConfig = serverConfig;
-  }
-
-  public boolean processMigration(Migration dbMigration, DdlWrite write) throws IOException {
-
-    this.changeSetCount = 0;
-    this.dbMigration = dbMigration;
-    this.write = write;
-
-    DdlHandler handler = handler();
-
-    List<ChangeSet> changeSets = dbMigration.getChangeSet();
-    for (ChangeSet changeSet : changeSets) {
-      if (!changeSet.getChangeSetChildren().isEmpty()) {
-        changeSetCount++;
-        handler.generate(write, changeSet);
-      }
-    }
-    handler.generateExtra(write);
-
-    return changeSetCount > 0;
-  }
-
-  /**
-   * Write as migration xml to the given file.
-   */
-  public void writeMigration(File resourcePath, int migrationVersion) throws IOException {
-
-    File file = new File(resourcePath, "v"+migrationVersion+".0.xml");
-
-    MigrationXmlWriter xmlWriter = new MigrationXmlWriter();
-    xmlWriter.write(dbMigration, file);
-
-    if (!write.isApplyEmpty()) {
-      FileWriter ddlWriter = createWriter(resourcePath, migrationVersion, ".0-apply.sql");
-      try {
-        writeApplyDdl(ddlWriter);
-        ddlWriter.flush();
-      } finally {
-        ddlWriter.close();
-      }
-
-      FileWriter rbWriter = createWriter(resourcePath, migrationVersion, ".0-applyRollback.sql");
-      try {
-        writeApplyRollbackDdl(rbWriter);
-        rbWriter.flush();
-      } finally {
-        rbWriter.close();
-      }
-    }
-
-    String content = write.drop().getBuffer();
-    if (!content.isEmpty()) {
-      writeFile(resourcePath, migrationVersion, ".0-drop.sql", content);
-    }
-
-    String dropHistory = write.dropHistory().getBuffer();
-    if (!dropHistory.isEmpty()) {
-      writeFile(resourcePath, migrationVersion, ".0-dropHistory.sql", dropHistory);
-    }
-  }
-
-  private FileWriter createWriter(File resourcePath, int migrationVersion, String suffix) throws IOException {
-
-    File applyFile = new File(resourcePath, "v" + migrationVersion + suffix);
-    return new FileWriter(applyFile);
-  }
-
-  private void writeFile(File resourcePath, int migrationVersion, String suffix, String content) throws IOException {
-
-    FileWriter ddlWriter =createWriter(resourcePath, migrationVersion, suffix);
-    try {
-      ddlWriter.append(content);
-      ddlWriter.flush();
-    } finally {
-      ddlWriter.close();
-    }
-  }
-
-
-  /**
-   * Return the 'Create' DDL.
-   */
-  private void writeApplyDdl(Writer writer) throws IOException {
-
-    writer.append(write.apply().getBuffer());
-    writer.append(write.applyForeignKeys().getBuffer());
-    writer.append(write.applyHistory().getBuffer());
-  }
-
-  /**
-   * Return the 'Rollback' DDL.
-   */
-  private void writeApplyRollbackDdl(Writer writer) throws IOException {
-
-    writer.append(write.rollbackForeignKeys().getBuffer());
-    writer.append(write.rollback().getBuffer());
-  }
-
-  /**
-   * Return the platform specific DdlHandler (to generate DDL).
-   */
-  private DdlHandler handler() {
-    return platform.createDdlHandler(serverConfig);
-  }
-
-}

src/main/java/com/avaje/ebean/dbmigration/model/ModelDiff.java

@@ -50,6 +50,15 @@ public class ModelDiff {
     this.baseModel = new ModelContainer();
   }
 
+
+  /**
+   * Return true if the apply and drop changes are both empty.
+   * This means there are no migration changes.
+   */
+  public boolean isEmpty() {
+    return applyChanges.isEmpty() && dropChanges.isEmpty();
+  }
+
   /**
    * Return the diff as a migration potentially containing
    * an apply changeSet and a drop changeSet.

src/main/java/com/avaje/ebean/dbmigration/model/PlatformDdlWriter.java

@@ -0,0 +1,135 @@
+package com.avaje.ebean.dbmigration.model;
+
+import com.avaje.ebean.config.ServerConfig;
+import com.avaje.ebean.config.dbplatform.DatabasePlatform;
+import com.avaje.ebean.dbmigration.ddlgeneration.DdlHandler;
+import com.avaje.ebean.dbmigration.ddlgeneration.DdlWrite;
+import com.avaje.ebean.dbmigration.migration.ChangeSet;
+import com.avaje.ebean.dbmigration.migration.Migration;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.Writer;
+import java.util.List;
+
+/**
+ * Writes migration changes as platform specific DDL.
+ */
+public class PlatformDdlWriter {
+
+  private final ServerConfig serverConfig;
+
+  private final DatabasePlatform platform;
+
+  private final String platformPrefix;
+
+  public PlatformDdlWriter(DatabasePlatform platform, ServerConfig serverConfig) {
+    this(platform, serverConfig, "");
+  }
+
+  public PlatformDdlWriter(DatabasePlatform platform, ServerConfig serverConfig, String platformPrefix) {
+    this.platform = platform;
+    this.serverConfig = serverConfig;
+    this.platformPrefix = platformPrefix;
+  }
+
+  /**
+   * Write the migration as platform specific ddl.
+   */
+  public void processMigration(Migration dbMigration, DdlWrite write, File writePath, int nextMajorVersion) throws IOException {
+
+    DdlHandler handler = handler();
+
+    List<ChangeSet> changeSets = dbMigration.getChangeSet();
+    for (ChangeSet changeSet : changeSets) {
+      if (!changeSet.getChangeSetChildren().isEmpty()) {
+        handler.generate(write, changeSet);
+      }
+    }
+    handler.generateExtra(write);
+
+    writePlatformDdl(write, writePath, nextMajorVersion);
+  }
+
+  /**
+   * Write the ddl files.
+   */
+  protected void writePlatformDdl(DdlWrite write, File resourcePath, int migrationVersion) throws IOException {
+
+    if (!write.isApplyEmpty()) {
+      FileWriter applyWriter = createWriter(resourcePath, migrationVersion, "apply.sql");
+      try {
+        writeApplyDdl(applyWriter, write);
+        applyWriter.flush();
+      } finally {
+        applyWriter.close();
+      }
+
+      if (!write.isApplyRollbackEmpty()) {
+        FileWriter applyRollbackWriter = createWriter(resourcePath, migrationVersion, "applyRollback.sql");
+        try {
+          writeApplyRollbackDdl(applyRollbackWriter, write);
+          applyRollbackWriter.flush();
+        } finally {
+          applyRollbackWriter.close();
+        }
+      }
+    }
+
+    if (!write.isDropEmpty()) {
+      FileWriter dropWriter = createWriter(resourcePath, migrationVersion, "drop.sql");
+      try {
+        writeDropDdl(dropWriter, write);
+        dropWriter.flush();
+      } finally {
+        dropWriter.close();
+      }
+    }
+  }
+
+  protected FileWriter createWriter(File resourcePath, int migrationVersion, String suffix) throws IOException {
+
+    File applyFile = new File(resourcePath, "v" + migrationVersion + ".0-" + platformPrefix + suffix);
+    return new FileWriter(applyFile);
+  }
+
+  /**
+   * Write the 'Apply' DDL buffers to the writer.
+   */
+  protected void writeApplyDdl(Writer writer, DdlWrite write) throws IOException {
+
+    // merge the apply buffers in the appropriate order
+    writer.append(write.apply().getBuffer());
+    writer.append(write.applyForeignKeys().getBuffer());
+    writer.append(write.applyHistory().getBuffer());
+  }
+
+  /**
+   * Write the 'Rollback' DDL buffers to the writer.
+   */
+  protected void writeApplyRollbackDdl(Writer writer, DdlWrite write) throws IOException {
+
+    // merge the rollback buffers in the appropriate order
+    writer.append(write.rollbackForeignKeys().getBuffer());
+    writer.append(write.rollback().getBuffer());
+  }
+
+  /**
+   * Write the 'Drop' DDL buffers to the writer.
+   */
+  protected void writeDropDdl(Writer writer, DdlWrite write) throws IOException {
+
+    // merge the rollback buffers in the appropriate order
+    writer.append(write.dropHistory().getBuffer());
+    writer.append(write.drop().getBuffer());
+  }
+
+  /**
+   * Return the platform specific DdlHandler (to generate DDL).
+   */
+  protected DdlHandler handler() {
+    return platform.createDdlHandler(serverConfig);
+  }
+
+}