#115 - Mapping - Add support for @ElementCollection enhancement

Add embedded bean support

src/main/java/io/ebean/bean/BeanCollection.java

@@ -72,6 +72,11 @@ public interface BeanCollection<E> extends Serializable {
    */
   boolean isSkipSave();
 
+  /**
+   * Return true if the collection holds modifications.
+   */
+  boolean holdsModifications();
+
   /**
    * Return the bean that owns this collection.
    */

src/main/java/io/ebean/common/AbstractBeanCollection.java

@@ -207,7 +207,8 @@ abstract class AbstractBeanCollection<E> implements BeanCollection<E> {
   /**
    * Return true if there are underlying additions or removals.
    */
-  boolean holdsModifications() {
+  @Override
+  public boolean holdsModifications() {
     return modifyHolder != null && modifyHolder.hasModifications();
   }
 

src/main/java/io/ebeaninternal/server/deploy/BeanCollectionUtil.java

@@ -11,6 +11,16 @@ import java.util.Map;
  */
 public class BeanCollectionUtil {
 
+  /**
+   * Return true if this is a bean collection and not considered dirty.
+   */
+  public static boolean isModified(Object collection) {
+    if ((collection instanceof BeanCollection<?>)) {
+      return ((BeanCollection<?>) collection).holdsModifications();
+    }
+    return true;
+  }
+
   /**
    * Return the details of the collection or map taking care to avoid
    * unnecessary fetching of the data.

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptor.java

@@ -235,7 +235,7 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
   /**
    * The type of bean this describes.
    */
-  private final Class<T> beanType;
+  final Class<T> beanType;
 
   protected final Class<?> rootBeanType;
 
@@ -428,8 +428,8 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
     this.name = InternString.intern(deploy.getName());
     this.baseTableAlias = "t0";
     this.fullName = InternString.intern(deploy.getFullName());
-    this.locationById = ProfileLocation.createAt(fullName+".byId");
-    this.locationAll = ProfileLocation.createAt(fullName+".all");
+    this.locationById = ProfileLocation.createAt(fullName + ".byId");
+    this.locationAll = ProfileLocation.createAt(fullName + ".all");
     this.profileBeanId = deploy.getProfileId();
     this.beanType = deploy.getBeanType();
     this.rootBeanType = PersistenceContextUtil.root(beanType);
@@ -776,7 +776,7 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
 
     for (BeanProperty prop : propertiesNonTransient) {
       if (prop.isUnique()) {
-        propertiesUnique.add(new BeanProperty[] { prop });
+        propertiesUnique.add(new BeanProperty[]{prop});
       }
     }
     // convert unique columns to properties
@@ -860,6 +860,16 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
     }
   }
 
+  /**
+   * Bind all the property values to the SqlUpdate.
+   */
+  public void bindElementValue(SqlUpdate insert, Object value) {
+    EntityBean bean = (EntityBean) value;
+    for (BeanProperty property : propertiesBaseScalar) {
+      insert.setNextParameter(property.getValue(bean));
+    }
+  }
+
   /**
    * Return the ReadAuditLogger for logging read audit events.
    */
@@ -1420,7 +1430,7 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
   @SuppressWarnings("unchecked")
   public void cacheBeanPutAll(Collection<?> beans) {
     if (!beans.isEmpty()) {
-      cacheHelp.beanPutAll((Collection<EntityBean>)beans);
+      cacheHelp.beanPutAll((Collection<EntityBean>) beans);
     }
   }
 
@@ -1879,12 +1889,19 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
   }
 
   /**
-   * Creates a new entitybean without invoking {@link BeanPostConstructListener#postCreate(Object)}
+   * Creates a new entity bean without invoking {@link BeanPostConstructListener#postCreate(Object)}
    */
   public EntityBean createEntityBean() {
     return createEntityBean(false);
   }
 
+  /**
+   * Create an entity bean for JSON marshalling (which differs for the element collection case).
+   */
+  public EntityBean createEntityBeanForJson() {
+    return createEntityBean();
+  }
+
   /**
    * Create a reference bean based on the id.
    */
@@ -2471,7 +2488,7 @@ public class BeanDescriptor<T> implements BeanType<T>, STreeType {
 
   /**
    * Return a property that is part of the SQL tree.
-   *
+   * <p>
    * The property can be a dynamic formula or a well known bean property.
    */
   @Override

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElement.java

@@ -1,34 +1,35 @@
 package io.ebeaninternal.server.deploy;
 
-import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonToken;
-import io.ebean.PersistenceIOException;
 import io.ebean.bean.EntityBean;
 import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
-import io.ebeaninternal.server.text.json.ReadJson;
-import io.ebeaninternal.server.text.json.SpiJsonWriter;
 import io.ebeaninternal.server.type.ScalarType;
 
-import java.io.IOException;
+import java.util.Arrays;
 
 /**
  * Bean descriptor used with ElementCollection (where we don't have a mapped type/class).
+ * <p>
+ * This is somewhat a BeanDescriptor created 'on the fly' for a specific element collection property
+ * with a unidirectional property and mapping etc specific to the property (and not the type if embedded).
  */
-class BeanDescriptorElement<T> extends BeanDescriptor<T> {
+abstract class BeanDescriptorElement<T> extends BeanDescriptor<T> {
 
-  private final ScalarType<Object> scalarType;
-  private final ElementHelp elementHelp;
+  final ElementHelp elementHelp;
 
   BeanDescriptorElement(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
     super(owner, deploy);
     this.elementHelp = elementHelp;
+  }
 
-    BeanProperty[] props = propertiesNonTransient();
-    if (props.length == 1) {
-      this.scalarType = props[0].getScalarType();
-    } else {
-      this.scalarType = null;
+  /**
+   * Find and return the first base scalar type (and we expect only 1).
+   */
+  ScalarType<Object> firstBaseScalarType() {
+    BeanProperty[] props = propertiesBaseScalar();
+    if (props.length != 1) {
+      throw new IllegalStateException("Expecting 1 property for element scalar but got " + Arrays.toString(props));
     }
+    return props[0].getScalarType();
   }
 
   @Override
@@ -36,35 +37,13 @@ class BeanDescriptorElement<T> extends BeanDescriptor<T> {
     return true;
   }
 
+  /**
+   * Our entity beans used are somewhat fake ones (ElementEntityBean) such that we hold the unidirectional property
+   * value (foreign key) and the actual element collection value (scalar or embedded plus map key).
+   */
   @Override
   protected EntityBean createPrototypeEntityBean(Class<T> beanType) {
     return new ElementEntityBean(properties);
   }
 
-  @Override
-  public void jsonWriteElement(SpiJsonWriter ctx, Object element) {
-    try {
-      scalarType.jsonWrite(ctx.gen(), element);
-    } catch (IOException e) {
-      throw new PersistenceIOException(e);
-    }
-  }
-
-  @Override
-  public Object jsonReadCollection(ReadJson readJson, EntityBean parentBean) throws IOException {
-
-    JsonParser parser = readJson.getParser();
-    ElementCollector add = elementHelp.createCollector();
-    do {
-      JsonToken token = parser.nextToken();
-      if (JsonToken.VALUE_NULL == token || JsonToken.END_ARRAY == token) {
-        break;
-      }
-      Object element = scalarType.jsonRead(parser);
-      add.addElement(element);
-    } while (true);
-
-    return add.collection();
-  }
-
 }

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementEmbedded.java

@@ -0,0 +1,79 @@
+package io.ebeaninternal.server.deploy;
+
+import io.ebean.PersistenceIOException;
+import io.ebean.SqlUpdate;
+import io.ebean.bean.EntityBean;
+import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
+import io.ebeaninternal.server.text.json.ReadJson;
+import io.ebeaninternal.server.text.json.SpiJsonWriter;
+
+import java.io.IOException;
+
+/**
+ * Bean descriptor used with element collection of list/set of embeddable.
+ */
+class BeanDescriptorElementEmbedded<T> extends BeanDescriptorElement<T> {
+
+  private final BeanPropertyAssocOne embeddedProperty;
+
+  private final EntityBean prototype;
+
+  private BeanDescriptor targetDescriptor;
+
+  BeanDescriptorElementEmbedded(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
+    super(owner, deploy, elementHelp);
+    try {
+      this.prototype = (EntityBean) beanType.newInstance();
+    } catch (Exception e) {
+      throw new IllegalStateException("Unable to create entity bean prototype for "+beanType);
+    }
+    BeanPropertyAssocOne<?>[] embedded = propertiesEmbedded();
+    if (embedded.length == 1) {
+      embeddedProperty = embedded[0];
+    } else {
+      embeddedProperty = null;
+    }
+  }
+
+  @Override
+  public void initialiseOther(BeanDescriptorInitContext initContext) {
+    super.initialiseOther(initContext);
+    this.targetDescriptor = embeddedProperty.getTargetDescriptor();
+  }
+
+  @Override
+  public EntityBean createEntityBeanForJson() {
+    return (EntityBean)prototype._ebean_newInstance();
+  }
+
+  public void bindElementValue(SqlUpdate insert, Object value) {
+    targetDescriptor.bindElementValue(insert, value);
+  }
+
+  @Override
+  public void jsonWriteElement(SpiJsonWriter ctx, Object element) {
+    writeJsonElement(ctx, element);
+  }
+
+  @Override
+  public T jsonRead(ReadJson jsonRead, String path) throws IOException {
+    return readJsonElement(jsonRead, path);
+  }
+
+  @SuppressWarnings("unchecked")
+  T readJsonElement(ReadJson jsonRead, String path) throws IOException {
+    return (T)targetDescriptor.jsonRead(jsonRead, path);
+  }
+
+  void writeJsonElement(SpiJsonWriter ctx, Object element) {
+    try {
+      if (element == null) {
+        ctx.writeNull();
+      } else {
+        targetDescriptor.jsonWrite(ctx, (EntityBean)element);
+      }
+    } catch (IOException e) {
+      throw new PersistenceIOException(e);
+    }
+  }
+}

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementEmbeddedMap.java

@@ -0,0 +1,84 @@
+package io.ebeaninternal.server.deploy;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import io.ebean.bean.EntityBean;
+import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
+import io.ebeaninternal.server.text.json.ReadJson;
+import io.ebeaninternal.server.text.json.SpiJsonWriter;
+import io.ebeaninternal.server.type.ScalarType;
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * Descriptor for element collection using Map with the value holding an embedded bean.
+ * <p>
+ * The expected limitation is that the key is a scalar type.
+ */
+class BeanDescriptorElementEmbeddedMap<T> extends BeanDescriptorElementEmbedded<T> {
+
+  private final ScalarType scalarTypeKey;
+
+  private final boolean stringKey;
+
+  BeanDescriptorElementEmbeddedMap(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
+    super(owner, deploy, elementHelp);
+    this.scalarTypeKey = firstBaseScalarType();
+    this.stringKey = String.class.equals(scalarTypeKey.getType());
+  }
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public void jsonWriteMapEntry(SpiJsonWriter ctx, Map.Entry<?, ?> entry) throws IOException {
+    ctx.writeStartObject();
+    if (stringKey) {
+      Object key = entry.getKey();
+      String keyName = (key == null) ? "null" : key.toString();
+      ctx.writeFieldName(keyName);
+      writeJsonElement(ctx, entry.getValue());
+    } else {
+      ctx.writeFieldName("key");
+      scalarTypeKey.jsonWrite(ctx.gen(), entry.getKey());
+      ctx.writeFieldName("value");
+      writeJsonElement(ctx, entry.getValue());
+    }
+    ctx.writeEndObject();
+  }
+
+  @Override
+  public Object jsonReadCollection(ReadJson readJson, EntityBean parentBean) throws IOException {
+
+    JsonParser parser = readJson.getParser();
+    ElementCollector add = elementHelp.createCollector();
+    do {
+      JsonToken token = parser.nextToken();
+      if (token != JsonToken.START_OBJECT) {
+        break;
+      }
+      if (stringKey) {
+        String key = parser.nextFieldName();
+        parser.nextToken();
+        Object val = readJsonElement(readJson, null);
+        add.addKeyValue(key, val);
+
+      } else {
+        parser.nextFieldName();
+        Object key = scalarTypeKey.jsonRead(parser);
+
+        parser.nextFieldName();
+        Object val = readJsonElement(readJson, null);
+        add.addKeyValue(key, val);
+      }
+
+      token = parser.nextToken();
+      if (token != JsonToken.END_OBJECT) {
+        break;
+      }
+
+    } while (true);
+
+    return add.collection();
+  }
+
+}

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementMap.java

@@ -1,97 +0,0 @@
-package io.ebeaninternal.server.deploy;
-
-import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonToken;
-import io.ebean.bean.EntityBean;
-import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
-import io.ebeaninternal.server.text.json.ReadJson;
-import io.ebeaninternal.server.text.json.SpiJsonWriter;
-import io.ebeaninternal.server.type.ScalarType;
-
-import java.io.IOException;
-import java.util.Map;
-
-/**
- * Bean descriptor used with ElementCollection (where we don't have a mapped type/class).
- */
-class BeanDescriptorElementMap<T> extends BeanDescriptor<T> {
-
-  private final ScalarType[] scalarTypes;
-  private final ElementHelp elementHelp;
-  private final boolean stringKey;
-
-  BeanDescriptorElementMap(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
-    super(owner, deploy);
-    this.elementHelp = elementHelp;
-    BeanProperty[] props = propertiesNonTransient();
-    this.scalarTypes = new ScalarType[props.length];
-    for (int i = 0; i < props.length; i++) {
-      scalarTypes[i] = props[i].getScalarType();
-    }
-    this.stringKey = String.class.equals(scalarTypes[0].getType());
-  }
-
-  @Override
-  public boolean isElementType() {
-    return true;
-  }
-
-  @Override
-  protected EntityBean createPrototypeEntityBean(Class<T> beanType) {
-    return new ElementEntityBean(properties);
-  }
-
-  @Override
-  @SuppressWarnings("unchecked")
-  public void jsonWriteMapEntry(SpiJsonWriter ctx, Map.Entry<?, ?> entry) throws IOException {
-      ctx.writeStartObject();
-      if (stringKey) {
-        Object key = entry.getKey();
-        String keyName = (key == null) ? "null" : key.toString();
-        ctx.writeFieldName(keyName);
-        scalarTypes[1].jsonWrite(ctx.gen(), entry.getValue());
-      } else {
-        ctx.writeFieldName("key");
-        scalarTypes[0].jsonWrite(ctx.gen(), entry.getKey());
-        ctx.writeFieldName("value");
-        scalarTypes[1].jsonWrite(ctx.gen(), entry.getValue());
-      }
-      ctx.writeEndObject();
-  }
-
-  @Override
-  public Object jsonReadCollection(ReadJson readJson, EntityBean parentBean) throws IOException {
-
-    JsonParser parser = readJson.getParser();
-    ElementCollector add = elementHelp.createCollector();
-    do {
-      JsonToken token = parser.nextToken();
-      if (token != JsonToken.START_OBJECT) {
-        break;
-      }
-      if (stringKey) {
-        String key = parser.nextFieldName();
-        parser.nextToken();
-        Object val = scalarTypes[0].jsonRead(parser);
-        add.addKeyValue(key, val);
-
-      } else {
-        parser.nextFieldName();
-        Object key= scalarTypes[0].jsonRead(parser);
-
-        parser.nextFieldName();
-        Object val = scalarTypes[0].jsonRead(parser);
-        add.addKeyValue(key, val);
-      }
-
-      token = parser.nextToken();
-      if (token != JsonToken.END_OBJECT) {
-        break;
-      }
-
-    } while (true);
-
-    return add.collection();
-  }
-
-}

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementScalar.java

@@ -0,0 +1,56 @@
+package io.ebeaninternal.server.deploy;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import io.ebean.PersistenceIOException;
+import io.ebean.SqlUpdate;
+import io.ebean.bean.EntityBean;
+import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
+import io.ebeaninternal.server.text.json.ReadJson;
+import io.ebeaninternal.server.text.json.SpiJsonWriter;
+import io.ebeaninternal.server.type.ScalarType;
+
+import java.io.IOException;
+
+/**
+ * Bean descriptor used with element collection mapped to a list or set of scalar values.
+ */
+class BeanDescriptorElementScalar<T> extends BeanDescriptorElement<T> {
+
+  private final ScalarType<Object> scalarType;
+
+  BeanDescriptorElementScalar(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
+    super(owner, deploy, elementHelp);
+    this.scalarType = firstBaseScalarType();
+  }
+
+  public void bindElementValue(SqlUpdate insert, Object value) {
+    insert.setNextParameter(value);
+  }
+
+  @Override
+  public void jsonWriteElement(SpiJsonWriter ctx, Object element) {
+    try {
+      scalarType.jsonWrite(ctx.gen(), element);
+    } catch (IOException e) {
+      throw new PersistenceIOException(e);
+    }
+  }
+
+  @Override
+  public Object jsonReadCollection(ReadJson readJson, EntityBean parentBean) throws IOException {
+
+    JsonParser parser = readJson.getParser();
+    ElementCollector add = elementHelp.createCollector();
+    do {
+      JsonToken token = parser.nextToken();
+      if (JsonToken.VALUE_NULL == token || JsonToken.END_ARRAY == token) {
+        break;
+      }
+      add.addElement(scalarType.jsonRead(parser));
+    } while (true);
+
+    return add.collection();
+  }
+
+}

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorElementScalarMap.java

@@ -0,0 +1,88 @@
+package io.ebeaninternal.server.deploy;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
+import io.ebean.bean.EntityBean;
+import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
+import io.ebeaninternal.server.text.json.ReadJson;
+import io.ebeaninternal.server.text.json.SpiJsonWriter;
+import io.ebeaninternal.server.type.ScalarType;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Map;
+
+/**
+ * Bean descriptor used with element collection mapped to Map where key and value are scalar types.
+ */
+class BeanDescriptorElementScalarMap<T> extends BeanDescriptorElement<T> {
+
+  private final ScalarType scalarTypeKey;
+  private final ScalarType scalarTypeVal;
+  private final boolean stringKey;
+
+  BeanDescriptorElementScalarMap(BeanDescriptorMap owner, DeployBeanDescriptor<T> deploy, ElementHelp elementHelp) {
+    super(owner, deploy, elementHelp);
+    BeanProperty[] props = propertiesNonTransient();
+    if (props.length != 2) {
+      throw new IllegalStateException("Expecting 2 properties for key and value but got " + Arrays.toString(props));
+    }
+    this.scalarTypeKey = props[0].getScalarType();
+    this.scalarTypeVal = props[1].getScalarType();
+    this.stringKey = String.class.equals(scalarTypeKey.getType());
+  }
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public void jsonWriteMapEntry(SpiJsonWriter ctx, Map.Entry<?, ?> entry) throws IOException {
+    ctx.writeStartObject();
+    if (stringKey) {
+      Object key = entry.getKey();
+      String keyName = (key == null) ? "null" : key.toString();
+      ctx.writeFieldName(keyName);
+      scalarTypeVal.jsonWrite(ctx.gen(), entry.getValue());
+    } else {
+      ctx.writeFieldName("key");
+      scalarTypeKey.jsonWrite(ctx.gen(), entry.getKey());
+      ctx.writeFieldName("value");
+      scalarTypeVal.jsonWrite(ctx.gen(), entry.getValue());
+    }
+    ctx.writeEndObject();
+  }
+
+  @Override
+  public Object jsonReadCollection(ReadJson readJson, EntityBean parentBean) throws IOException {
+
+    JsonParser parser = readJson.getParser();
+    ElementCollector add = elementHelp.createCollector();
+    do {
+      JsonToken token = parser.nextToken();
+      if (token != JsonToken.START_OBJECT) {
+        break;
+      }
+      if (stringKey) {
+        String key = parser.nextFieldName();
+        parser.nextToken();
+        Object val = scalarTypeVal.jsonRead(parser);
+        add.addKeyValue(key, val);
+
+      } else {
+        parser.nextFieldName();
+        Object key = scalarTypeKey.jsonRead(parser);
+
+        parser.nextFieldName();
+        Object val = scalarTypeVal.jsonRead(parser);
+        add.addKeyValue(key, val);
+      }
+
+      token = parser.nextToken();
+      if (token != JsonToken.END_OBJECT) {
+        break;
+      }
+
+    } while (true);
+
+    return add.collection();
+  }
+
+}

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorJsonHelp.java

@@ -118,7 +118,7 @@ public class BeanDescriptorJsonHelp<T> {
 
   protected T jsonReadObject(ReadJson readJson, String path) throws IOException {
 
-    EntityBean bean = desc.createEntityBean();
+    EntityBean bean = desc.createEntityBeanForJson();
     return jsonReadProperties(readJson, bean, path);
   }
 

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorManager.java

@@ -637,7 +637,7 @@ public class BeanDescriptorManager implements BeanDescriptorMap {
   /**
    * Return a BeanTable for an ElementCollection.
    */
-  public BeanTable getCollectionBeanTable(String fullTableName, Class<?> targetType) {
+  public BeanTable createCollectionBeanTable(String fullTableName, Class<?> targetType) {
     return new BeanTable(this, fullTableName, targetType);
   }
 
@@ -1637,13 +1637,21 @@ public class BeanDescriptorManager implements BeanDescriptorMap {
   /**
    * Create a BeanDescriptor for an ElementCollection target.
    */
-  public <A> BeanDescriptor<A> createElementDescriptor(DeployBeanDescriptor<A> elementDescriptor, ManyType manyType) {
+  public <A> BeanDescriptor<A> createElementDescriptor(DeployBeanDescriptor<A> elementDescriptor, ManyType manyType, boolean scalar) {
 
     ElementHelp elementHelp = elementHelper(manyType);
     if (manyType.isMap()) {
-      return new BeanDescriptorElementMap<>(this, elementDescriptor, elementHelp);
+      if (scalar) {
+        return new BeanDescriptorElementScalarMap<>(this, elementDescriptor, elementHelp);
+      } else {
+        return new BeanDescriptorElementEmbeddedMap<>(this, elementDescriptor, elementHelp);
+      }
+    }
+    if (scalar) {
+      return new BeanDescriptorElementScalar<>(this, elementDescriptor, elementHelp);
+    } else {
+      return new BeanDescriptorElementEmbedded<>(this, elementDescriptor, elementHelp);
     }
-    return new BeanDescriptorElement<>(this, elementDescriptor, elementHelp);
   }
 
   private ElementHelp elementHelper(ManyType manyType) {

src/main/java/io/ebeaninternal/server/deploy/BeanPropertyAssocMany.java

@@ -70,6 +70,11 @@ public class BeanPropertyAssocMany<T> extends BeanPropertyAssoc<T> implements ST
 
   private final boolean elementCollection;
 
+  /**
+   * Descriptor for the 'target' when the property maps to an element collection.
+   */
+  BeanDescriptor<T> elementDescriptor;
+
   /**
    * Order by used when fetch joining the associated many.
    */
@@ -116,6 +121,7 @@ public class BeanPropertyAssocMany<T> extends BeanPropertyAssoc<T> implements ST
     this.hasOrderColumn = deploy.hasOrderColumn();
     this.manyToMany = deploy.isManyToMany();
     this.elementCollection = deploy.isElementCollection();
+    this.elementDescriptor = deploy.getElementDescriptor();
     this.manyType = deploy.getManyType();
     this.mapKey = deploy.getMapKey();
     this.fetchOrderBy = deploy.getFetchOrderBy();
@@ -136,6 +142,19 @@ public class BeanPropertyAssocMany<T> extends BeanPropertyAssoc<T> implements ST
   public void initialise(BeanDescriptorInitContext initContext) {
     super.initialise(initContext);
     initialiseAssocMany();
+    if (elementCollection) {
+      // initialise all non-id properties (we don't have an Id property)
+      elementDescriptor.initialiseOther(initContext);
+    }
+  }
+
+  @Override
+  void initialiseTargetDescriptor(BeanDescriptorInitContext initContext) {
+    if (elementCollection) {
+      targetDescriptor = elementDescriptor;
+    } else {
+      targetDescriptor = descriptor.getBeanDescriptor(targetType);
+    }
   }
 
   private void initialiseAssocMany() {
@@ -170,7 +189,7 @@ public class BeanPropertyAssocMany<T> extends BeanPropertyAssoc<T> implements ST
   }
 
   String targetTable() {
-    return targetDescriptor.getBaseTable();
+    return beanTable.getBaseTable();
   }
 
   /**
@@ -883,18 +902,22 @@ public class BeanPropertyAssocMany<T> extends BeanPropertyAssoc<T> implements ST
   }
 
   public void jsonWriteMapEntry(SpiJsonWriter ctx, Map.Entry<?, ?> entry) throws IOException {
-    // Writing as json array rather than object ...
-    targetDescriptor.jsonWrite(ctx, (EntityBean) entry.getValue());
+    elementDescriptor.jsonWriteMapEntry(ctx, entry);
   }
 
   public void jsonWriteElementValue(SpiJsonWriter ctx, Object element) {
-    throw new IllegalStateException("Unexpected - expect Element override");
+    elementDescriptor.jsonWriteElement(ctx, element);
   }
 
   /**
    * Read the collection (JSON Array) containing entity beans.
    */
   public Object jsonReadCollection(ReadJson readJson, EntityBean parentBean) throws IOException {
+
+    if (elementDescriptor != null && manyType.isMap()) {
+      return elementDescriptor.jsonReadCollection(readJson, parentBean);
+    }
+
     BeanCollection<?> collection = createEmpty(parentBean);
     BeanCollectionAdd add = getBeanCollectionAdd(collection, null);
     do {
@@ -913,4 +936,11 @@ public class BeanPropertyAssocMany<T> extends BeanPropertyAssoc<T> implements ST
 
     return collection;
   }
+
+  /**
+   * Bind all the property values to the SqlUpdate.
+   */
+  public void bindElementValue(SqlUpdate insert, Object value) {
+    targetDescriptor.bindElementValue(insert, value);
+  }
 }

src/main/java/io/ebeaninternal/server/deploy/BeanPropertySimpleCollection.java

@@ -1,47 +1,21 @@
 package io.ebeaninternal.server.deploy;
 
+import io.ebean.SqlUpdate;
 import io.ebean.bean.EntityBean;
 import io.ebeaninternal.server.deploy.meta.DeployBeanPropertySimpleCollection;
 import io.ebeaninternal.server.text.json.ReadJson;
-import io.ebeaninternal.server.text.json.SpiJsonWriter;
 
 import java.io.IOException;
-import java.util.Map;
 
 public class BeanPropertySimpleCollection<T> extends BeanPropertyAssocMany<T> {
 
-  private BeanDescriptor<T> elementDescriptor;
-
   public BeanPropertySimpleCollection(BeanDescriptor<?> descriptor, DeployBeanPropertySimpleCollection<T> deploy) {
     super(descriptor, deploy);
-    this.elementDescriptor = deploy.getElementDescriptor();
   }
 
   @Override
-  public void initialise(BeanDescriptorInitContext initContext) {
-    super.initialise(initContext);
-    if (isElementCollection()) {
-      // initialise all non-id properties (we don't have an Id property)
-      elementDescriptor.initialiseOther(initContext);
-    }
-  }
-
-  void initialiseTargetDescriptor(BeanDescriptorInitContext initContext) {
-    if (isElementCollection()) {
-      targetDescriptor = elementDescriptor;
-    } else {
-      targetDescriptor = descriptor.getBeanDescriptor(targetType);
-    }
-  }
-
-  @Override
-  public void jsonWriteMapEntry(SpiJsonWriter ctx, Map.Entry<?, ?> entry) throws IOException {
-    elementDescriptor.jsonWriteMapEntry(ctx, entry);
-  }
-
-  @Override
-  public void jsonWriteElementValue(SpiJsonWriter ctx, Object element) {
-    elementDescriptor.jsonWriteElement(ctx, element);
+  public void bindElementValue(SqlUpdate insert, Object value) {
+    insert.setNextParameter(value);
   }
 
   @Override

src/main/java/io/ebeaninternal/server/deploy/meta/DeployBeanPropertyAssocMany.java

@@ -4,6 +4,9 @@ import io.ebean.bean.BeanCollection.ModifyListenMode;
 import io.ebeaninternal.server.deploy.BeanDescriptor;
 import io.ebeaninternal.server.deploy.ManyType;
 import io.ebeaninternal.server.deploy.TableJoin;
+import io.ebeaninternal.server.type.TypeReflectHelper;
+
+import java.lang.reflect.Type;
 
 /**
  * Property mapped to a List Set or Map.
@@ -179,6 +182,14 @@ public class DeployBeanPropertyAssocMany<T> extends DeployBeanPropertyAssoc<T> {
     return fetchOrderBy;
   }
 
+  /**
+   * Return the type of the map key (valid only when this property is a Map).
+   */
+  public Class<?> getMapKeyType() {
+    Type genericType = getField().getGenericType();
+    return TypeReflectHelper.getMapKeyType(genericType);
+  }
+
   /**
    * Return the default mapKey when returning a Map.
    */

src/main/java/io/ebeaninternal/server/deploy/parse/AnnotationAssocManys.java

@@ -15,6 +15,7 @@ import io.ebeaninternal.server.deploy.BeanTable;
 import io.ebeaninternal.server.deploy.meta.DeployBeanDescriptor;
 import io.ebeaninternal.server.deploy.meta.DeployBeanProperty;
 import io.ebeaninternal.server.deploy.meta.DeployBeanPropertyAssocMany;
+import io.ebeaninternal.server.deploy.meta.DeployBeanPropertyAssocOne;
 import io.ebeaninternal.server.deploy.meta.DeployOrderColumn;
 import io.ebeaninternal.server.deploy.meta.DeployTableJoin;
 import io.ebeaninternal.server.deploy.meta.DeployTableJoinColumn;
@@ -204,7 +205,7 @@ class AnnotationAssocManys extends AnnotationParser {
       }
     }
 
-    BeanTable beanTable = factory.getCollectionBeanTable(fullTableName, prop.getTargetType());
+    BeanTable beanTable = factory.createCollectionBeanTable(fullTableName, prop.getTargetType());
     prop.setBeanTable(beanTable);
 
     Class<?> elementType = prop.getTargetType();
@@ -212,8 +213,6 @@ class AnnotationAssocManys extends AnnotationParser {
     DeployBeanDescriptor<?> elementDescriptor = factory.createDeployDescriptor(elementType);
     elementDescriptor.setBaseTable(new TableName(fullTableName), readConfig.getAsOfViewSuffix(), readConfig.getVersionsBetweenSuffix());
 
-    ScalarType<?> scalarType = util.getTypeManager().getScalarType(elementType);
-
     int sortOrder = 0;
     if (!prop.getManyType().isMap()) {
       elementDescriptor.setProperties(new String[]{"value"});
@@ -225,27 +224,46 @@ class AnnotationAssocManys extends AnnotationParser {
         dbKeyColumn = mapKeyColumn.name();
       }
 
-      DeployBeanProperty keyProp = new DeployBeanProperty(elementDescriptor, elementType, scalarType, null);
+      ScalarType<?> keyScalarType = util.getTypeManager().getScalarType(prop.getMapKeyType());
+
+      DeployBeanProperty keyProp = new DeployBeanProperty(elementDescriptor, elementType, keyScalarType, null);
       setElementProperty(keyProp, "key", dbKeyColumn, sortOrder++);
       elementDescriptor.addBeanProperty(keyProp);
       if (mapKeyColumn != null) {
         keyProp.setDbLength(mapKeyColumn.length());
         keyProp.setDbScale(mapKeyColumn.scale());
+        keyProp.setUnique(mapKeyColumn.unique());
       }
     }
 
-    DeployBeanProperty valueProp = new DeployBeanProperty(elementDescriptor, elementType, scalarType, null);
-    setElementProperty(valueProp, "value", prop.getDbColumn(), sortOrder++);
-    if (column != null) {
-      valueProp.setDbLength(column.length());
-      valueProp.setDbScale(column.scale());
+    ScalarType<?> valueScalarType = util.getTypeManager().getScalarType(elementType);
+
+    boolean scalar = true;
+    if (valueScalarType == null) {
+      // embedded value type
+      scalar = false;
+      DeployBeanPropertyAssocOne valueProp = new DeployBeanPropertyAssocOne<>(elementDescriptor, elementType);
+      valueProp.setName("value");
+      valueProp.setEmbedded();
+      valueProp.setElementProperty();
+      valueProp.setSortOrder(sortOrder++);
+      elementDescriptor.addBeanProperty(valueProp);
+
+    } else {
+      // scalar value type
+      DeployBeanProperty valueProp = new DeployBeanProperty(elementDescriptor, elementType, valueScalarType, null);
+      setElementProperty(valueProp, "value", prop.getDbColumn(), sortOrder++);
+      if (column != null) {
+        valueProp.setDbLength(column.length());
+        valueProp.setDbScale(column.scale());
+      }
+      elementDescriptor.addBeanProperty(valueProp);
     }
 
-    elementDescriptor.addBeanProperty(valueProp);
     elementDescriptor.setName(prop.getFullBeanName());
 
     factory.createUnidirectional(elementDescriptor, prop.getOwningType(), beanTable, prop.getTableJoin());
-    prop.setElementDescriptor(factory.createElementDescriptor(elementDescriptor, prop.getManyType()));
+    prop.setElementDescriptor(factory.createElementDescriptor(elementDescriptor, prop.getManyType(), scalar));
   }
 
   private void setElementProperty(DeployBeanProperty elementProp, String name, String dbColumn, int sortOrder) {
@@ -307,7 +325,7 @@ class AnnotationAssocManys extends AnnotationParser {
    * Return the full table name
    */
   private String getFullTableName(CollectionTable collectionTable) {
-    if (collectionTable == null) {
+    if (collectionTable == null || collectionTable.name().isEmpty()) {
       return null;
     }
     StringBuilder sb = new StringBuilder();

src/main/java/io/ebeaninternal/server/persist/DefaultPersister.java

@@ -906,10 +906,10 @@ public final class DefaultPersister implements Persister {
       return new SaveManyBeans(insertedParent, many, parentBean, request, this);
 
     } else if (many.getManyType().isMap()) {
-      return new SaveManySimpleMap(insertedParent, many, parentBean, request);
+      return new SaveManyElementCollectionMap(insertedParent, many, parentBean, request);
 
     } else {
-      return new SaveManySimpleCollection(insertedParent, many, parentBean, request);
+      return new SaveManyElementCollection(insertedParent, many, parentBean, request);
     }
   }
 

src/main/java/io/ebeaninternal/server/persist/SaveManyBase.java

@@ -1,5 +1,6 @@
 package io.ebeaninternal.server.persist;
 
+import io.ebean.bean.BeanCollection;
 import io.ebean.bean.EntityBean;
 import io.ebeaninternal.api.SpiEbeanServer;
 import io.ebeaninternal.api.SpiTransaction;
@@ -34,4 +35,17 @@ abstract class SaveManyBase {
    */
   abstract void save();
 
+  void resetModifyState() {
+    if (value instanceof BeanCollection<?>) {
+      modifyListenReset((BeanCollection<?>) value);
+    }
+  }
+
+  void modifyListenReset(BeanCollection<?> c) {
+    if (insertedParent) {
+      // after insert set the modify listening mode for private owned etc
+      c.setModifyListening(many.getModifyListenMode());
+    }
+    c.modifyReset();
+  }
 }

src/main/java/io/ebeaninternal/server/persist/SaveManyBeans.java

@@ -89,20 +89,6 @@ class SaveManyBeans extends SaveManyBase {
     return BeanCollection.ModifyListenMode.REMOVALS == many.getModifyListenMode();
   }
 
-  private void modifyListenReset(BeanCollection<?> c) {
-    if (insertedParent) {
-      // after insert set the modify listening mode for private owned etc
-      c.setModifyListening(many.getModifyListenMode());
-    }
-    c.modifyReset();
-  }
-
-  private void resetModifyState() {
-    if (value instanceof BeanCollection<?>) {
-      modifyListenReset((BeanCollection<?>) value);
-    }
-  }
-
   /**
    * Save the details from a OneToMany collection.
    */

src/main/java/io/ebeaninternal/server/persist/SaveManyElementCollection.java

@@ -12,9 +12,9 @@ import java.util.Collection;
 /**
  * Save details for a simple scalar element collection.
  */
-class SaveManySimpleCollection extends SaveManyBase {
+class SaveManyElementCollection extends SaveManyBase {
 
-  SaveManySimpleCollection(boolean insertedParent, BeanPropertyAssocMany<?> many, EntityBean parentBean, PersistRequestBean<?> request) {
+  SaveManyElementCollection(boolean insertedParent, BeanPropertyAssocMany<?> many, EntityBean parentBean, PersistRequestBean<?> request) {
     super(insertedParent, many, parentBean, request);
   }
 
@@ -22,16 +22,18 @@ class SaveManySimpleCollection extends SaveManyBase {
   void save() {
 
     Collection<?> collection = BeanCollectionUtil.getActualEntries(value);
-    if (collection == null) {
+    if (collection == null || !BeanCollectionUtil.isModified(value)) {
       return;
     }
 
     Object parentId = request.getBeanId();
 
-    SqlUpdate sqlDelete = many.deleteByParentId(parentId, null);
-
     SpiEbeanServer server = request.getServer();
-    server.execute(sqlDelete, transaction);
+
+    if (!insertedParent) {
+      SqlUpdate sqlDelete = many.deleteByParentId(parentId, null);
+      server.execute(sqlDelete, transaction);
+    }
 
     transaction.depth(+1);
 
@@ -40,11 +42,12 @@ class SaveManySimpleCollection extends SaveManyBase {
 
     for (Object value : collection) {
 
-      sqlInsert.setParameter(1, parentId);
-      sqlInsert.setParameter(2, value);
+      sqlInsert.setNextParameter(parentId);
+      many.bindElementValue(sqlInsert, value);
       server.execute(sqlInsert, transaction);
     }
 
     transaction.depth(-1);
+    resetModifyState();
   }
 }

src/main/java/io/ebeaninternal/server/persist/SaveManyElementCollectionMap.java

@@ -13,9 +13,9 @@ import java.util.Set;
 /**
  * Save details for a simple scalar map element collection.
  */
-class SaveManySimpleMap extends SaveManyBase {
+class SaveManyElementCollectionMap extends SaveManyBase {
 
-  SaveManySimpleMap(boolean insertedParent, BeanPropertyAssocMany<?> many, EntityBean parentBean, PersistRequestBean<?> request) {
+  SaveManyElementCollectionMap(boolean insertedParent, BeanPropertyAssocMany<?> many, EntityBean parentBean, PersistRequestBean<?> request) {
     super(insertedParent, many, parentBean, request);
   }
 
@@ -23,17 +23,19 @@ class SaveManySimpleMap extends SaveManyBase {
   @Override
   void save() {
 
-    Set<Map.Entry<?, ?>> entries = (Set<Map.Entry<?, ?>>)BeanCollectionUtil.getActualEntries(value);
-    if (entries == null) {
+    Set<Map.Entry<?, ?>> entries = (Set<Map.Entry<?, ?>>) BeanCollectionUtil.getActualEntries(value);
+    if (entries == null || !BeanCollectionUtil.isModified(value)) {
       return;
     }
 
     Object parentId = request.getBeanId();
 
-    SqlUpdate sqlDelete = many.deleteByParentId(parentId, null);
-
     SpiEbeanServer server = request.getServer();
-    server.execute(sqlDelete, transaction);
+
+    if (!insertedParent) {
+      SqlUpdate sqlDelete = many.deleteByParentId(parentId, null);
+      server.execute(sqlDelete, transaction);
+    }
 
     transaction.depth(+1);
 
@@ -41,12 +43,13 @@ class SaveManySimpleMap extends SaveManyBase {
     SqlUpdate sqlInsert = server.createSqlUpdate(insert);
 
     for (Map.Entry<?, ?> entry : entries) {
-      sqlInsert.setParameter(1, parentId);
-      sqlInsert.setParameter(2, entry.getKey());
-      sqlInsert.setParameter(3, entry.getValue());
+      sqlInsert.setNextParameter(parentId);
+      sqlInsert.setNextParameter(entry.getKey());
+      many.bindElementValue(sqlInsert, entry.getValue());
       server.execute(sqlInsert, transaction);
     }
 
     transaction.depth(-1);
+    resetModifyState();
   }
 }

src/main/java/io/ebeaninternal/server/type/TypeReflectHelper.java

@@ -30,6 +30,13 @@ public class TypeReflectHelper {
     }
   }
 
+  /**
+   * Return the type of the map key.
+   */
+  public static Class<?> getMapKeyType(Type genericType) {
+    return getClass(getValueType(genericType));
+  }
+
   /**
    * Return the value type of a collection type (list, set, map values).
    */