#1739 - Entity with just @Id and @OneToMany fields produces broken insert query

src/main/java/io/ebeaninternal/server/persist/dml/InsertMeta.java

@@ -177,8 +177,12 @@ public final class InsertMeta {
     request.setInsertSetMode();
 
     request.append("insert into ").append(table);
-    request.append(" (");
+    if (nullId && noColumnsForInsert(draftTable)) {
+      request.append(" default values");
+      return request.toString();
+    }
 
+    request.append(" (");
     if (!nullId) {
       id.dmlAppend(request);
     }
@@ -200,8 +204,16 @@ public final class InsertMeta {
     request.append(") values (");
     request.append(request.getInsertBindBuffer());
     request.append(")");
-
     return request.toString();
   }
 
+  /**
+   * Return true if the insert actually contains no columns.
+   */
+  private boolean noColumnsForInsert(boolean draftTable) {
+    return shadowFKey == null
+      && discriminator == null
+      && (draftTable ? all.isEmpty() : allExcludeDraftOnly.isEmpty());
+  }
+
 }

src/main/java/io/ebeaninternal/server/persist/dmlbind/BindableList.java

@@ -33,6 +33,10 @@ public class BindableList implements Bindable {
     return new BindableList(copy);
   }
 
+  public boolean isEmpty() {
+    return items.length == 0;
+  }
+
   @Override
   public boolean isDraftOnly() {
     return false;

src/test/java/org/tests/insert/OnlyIdEntity.java

@@ -0,0 +1,19 @@
+package org.tests.insert;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+
+@Entity
+public class OnlyIdEntity {
+
+  @Id
+  long id;
+
+  public long getId() {
+    return id;
+  }
+
+  public void setId(long id) {
+    this.id = id;
+  }
+}

src/test/java/org/tests/insert/TestOnlyIdEntity.java

@@ -0,0 +1,32 @@
+package org.tests.insert;
+
+import io.ebean.DB;
+import io.ebean.Database;
+import io.ebean.annotation.ForPlatform;
+import io.ebean.annotation.Platform;
+import org.ebeantest.LoggedSqlCollector;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class TestOnlyIdEntity {
+
+  @ForPlatform({Platform.H2, Platform.POSTGRES})
+  @Test
+  public void insert() {
+
+    final Database database = DB.getDefault();
+
+    LoggedSqlCollector.start();
+    OnlyIdEntity bean = new OnlyIdEntity();
+    database.save(bean);
+
+    List<String> sql = LoggedSqlCollector.stop();
+
+    assertThat(bean.getId()).isGreaterThan(0);
+    assertThat(sql).hasSize(1);
+    assertThat(sql.get(0)).contains("insert into only_id_entity default values");
+  }
+}