private <S extends Object> S read(final SolrPersistentEntity<S> entity, final Map<String, ?> source,
		Object parent) {
	ParameterValueProvider<SolrPersistentProperty> parameterValueProvider = getParameterValueProvider(entity,
			source, parent);

	EntityInstantiator instantiator = instantiators.getInstantiatorFor(entity);
	final S instance = instantiator.createInstance(entity, parameterValueProvider);
	final PersistentPropertyAccessor accessor = new ConvertingPropertyAccessor(entity.getPropertyAccessor(instance),
			getConversionService());

	entity.doWithProperties(new PropertyHandler<SolrPersistentProperty>() {

		@Override
		public void doWithPersistentProperty(SolrPersistentProperty persistentProperty) {
			if (entity.isConstructorArgument(persistentProperty)) {
				return;
			}

			Object o = getValue(persistentProperty, source, instance);
			if (o != null) {
				accessor.setProperty(persistentProperty, o);
			}
		}
	});

	return instance;
}
 

private <S> S read(VaultPersistentEntity<S> entity, SecretDocument source) {

		ParameterValueProvider<VaultPersistentProperty> provider = getParameterProvider(entity, source);
		EntityInstantiator instantiator = this.instantiators.getInstantiatorFor(entity);
		S instance = instantiator.createInstance(entity, provider);

		PersistentPropertyAccessor accessor = new ConvertingPropertyAccessor(entity.getPropertyAccessor(instance),
				this.conversionService);

		VaultPersistentProperty idProperty = entity.getIdProperty();
		SecretDocumentAccessor documentAccessor = new SecretDocumentAccessor(source);

		// make sure id property is set before all other properties
		Object idValue;

		if (entity.requiresPropertyPopulation()) {
			if (idProperty != null && !entity.isConstructorArgument(idProperty)
					&& documentAccessor.hasValue(idProperty)) {

				idValue = readIdValue(idProperty, documentAccessor);
				accessor.setProperty(idProperty, idValue);
			}

			VaultPropertyValueProvider valueProvider = new VaultPropertyValueProvider(documentAccessor);

			readProperties(entity, accessor, idProperty, documentAccessor, valueProvider);
		}

		return instance;
	}
 

@Override
@SuppressWarnings("unchecked")
public <R> R read(Class<R> aClass, BaseEntity entity) {
	if (entity == null) {
		return null;
	}
	DatastorePersistentEntity<R> ostensiblePersistentEntity = (DatastorePersistentEntity<R>) this.mappingContext
			.getPersistentEntity(aClass);

	if (ostensiblePersistentEntity == null) {
		throw new DatastoreDataException("Unable to convert Datastore Entity to " + aClass);
	}

	EntityPropertyValueProvider propertyValueProvider = new EntityPropertyValueProvider(entity, this.conversions);

	DatastorePersistentEntity<?> persistentEntity = getDiscriminationPersistentEntity(ostensiblePersistentEntity,
			propertyValueProvider);

	ParameterValueProvider<DatastorePersistentProperty> parameterValueProvider =
			new PersistentEntityParameterValueProvider<>(persistentEntity, propertyValueProvider, null);

	EntityInstantiator instantiator = this.instantiators.getInstantiatorFor(persistentEntity);
	Object instance;
	try {
		instance = instantiator.createInstance(persistentEntity, parameterValueProvider);
		PersistentPropertyAccessor accessor = persistentEntity.getPropertyAccessor(instance);

		persistentEntity.doWithColumnBackedProperties((datastorePersistentProperty) -> {
			// if a property is a constructor argument, it was already computed on instantiation
			if (!persistentEntity.isConstructorArgument(datastorePersistentProperty)) {
				Object value = propertyValueProvider
						.getPropertyValue(datastorePersistentProperty);
				accessor.setProperty(datastorePersistentProperty, value);
			}
		});
	}
	catch (DatastoreDataException ex) {
		throw new DatastoreDataException("Unable to read " + persistentEntity.getName() + " entity", ex);
	}

	return (R) instance;
}
 

/**
 * Reads a single POJO from a Cloud Spanner row.
 * @param type the type of POJO
 * @param source the Cloud Spanner row
 * @param includeColumns the columns to read. If null then all columns will be read.
 * @param allowMissingColumns if true, then properties with no corresponding column are
 * not mapped. If false, then an exception is thrown.
 * @param <R> the type of the POJO.
 * @return the POJO
 */
@SuppressWarnings("unchecked")
public <R> R read(Class<R> type, Struct source, Set<String> includeColumns,
		boolean allowMissingColumns) {
	boolean readAllColumns = includeColumns == null;
	SpannerPersistentEntity<R> persistentEntity =
			(SpannerPersistentEntity<R>) this.spannerMappingContext.getPersistentEntity(type);

	StructAccessor structAccessor = new StructAccessor(source);

	StructPropertyValueProvider propertyValueProvider = new StructPropertyValueProvider(
			structAccessor,
			this.converter,
			this, allowMissingColumns);

	PreferredConstructor<?, SpannerPersistentProperty> persistenceConstructor = persistentEntity
			.getPersistenceConstructor();

	// @formatter:off
	ParameterValueProvider<SpannerPersistentProperty> parameterValueProvider =
					new PersistentEntityParameterValueProvider<>(persistentEntity, propertyValueProvider, null);
	// @formatter:on

	EntityInstantiator instantiator = this.instantiators.getInstantiatorFor(persistentEntity);
	R instance = instantiator.createInstance(persistentEntity, parameterValueProvider);
	PersistentPropertyAccessor accessor = persistentEntity.getPropertyAccessor(instance);

	persistentEntity.doWithProperties(
			(PropertyHandler<SpannerPersistentProperty>) (spannerPersistentProperty) -> {
				if (spannerPersistentProperty.isEmbedded()) {
					accessor.setProperty(spannerPersistentProperty,
							read(spannerPersistentProperty.getType(), source,
									includeColumns, allowMissingColumns));
				}
				else {
					if (!shouldSkipProperty(structAccessor, spannerPersistentProperty,
							includeColumns, readAllColumns, allowMissingColumns,
							persistenceConstructor)) {

						Object value = propertyValueProvider
								.getPropertyValue(spannerPersistentProperty);
						accessor.setProperty(spannerPersistentProperty, value);
					}
				}
			});

	return instance;
}
 

/**
 * Typical code used to read entities in {@link org.springframework.data.convert.EntityReader}.
 *
 * @param data
 * @param classToRead
 * @param queryCustomConversions {@literal true} to call {@link CustomConversions#hasCustomReadTarget(Class, Class)}.
 * @return
 */
@SuppressWarnings("unchecked")
private Object read(Map<String, Object> data, Class<?> classToRead, boolean queryCustomConversions) {

	if (queryCustomConversions) {
		customConversions.hasCustomReadTarget(Map.class, classToRead);
	}

	MyPersistentEntity<?> persistentEntity = context.getRequiredPersistentEntity(classToRead);
	PreferredConstructor<?, MyPersistentProperty> constructor = persistentEntity.getPersistenceConstructor();

	ParameterValueProvider<MyPersistentProperty> provider = constructor.isNoArgConstructor() //
			? NONE //
			: new ParameterValueProvider<MyPersistentProperty>() {

				@Override
				public <T> T getParameterValue(Parameter<T, MyPersistentProperty> parameter) {
					return (T) getValue(data, parameter.getName(), parameter.getType().getType(), queryCustomConversions);
				}
			};

	EntityInstantiator instantiator = instantiators.getInstantiatorFor(persistentEntity);
	Object instance = instantiator.createInstance(persistentEntity, provider);

	if (!persistentEntity.requiresPropertyPopulation()) {
		return instance;
	}

	PropertyValueProvider<MyPersistentProperty> valueProvider = new PropertyValueProvider<MyPersistentProperty>() {

		@Override
		public <T> T getPropertyValue(MyPersistentProperty property) {
			return (T) getValue(data, property.getName(), property.getType(), queryCustomConversions);
		}
	};

	PersistentPropertyAccessor<?> accessor = new ConvertingPropertyAccessor<>(
			persistentEntity.getPropertyAccessor(instance), conversionService);

	readProperties(data, persistentEntity, valueProvider, accessor);

	return accessor.getBean();
}
 

/**
 * Read an incoming {@link CrateDocument} into the target entity.
 *
 * @param entity the target entity.
 * @param source the document to convert.
 * @param parent an optional parent object.
 * @param <R> the entity type.
 * @return the converted entity.
 */
@SuppressWarnings("unchecked")
protected <R> R read(final CratePersistentEntity<R> entity, final CrateDocument source, final Object parent) {
	
	final DefaultSpELExpressionEvaluator evaluator = new DefaultSpELExpressionEvaluator(source, spELContext);
	
    ParameterValueProvider<CratePersistentProperty> provider = getParameterProvider(entity, source, evaluator, parent);
    
    EntityInstantiator instantiator = instantiators.getInstantiatorFor(entity);

    R instance = instantiator.createInstance(entity, provider);
    final PersistentPropertyAccessor propertyAccessor = entity.getPropertyAccessor(instance);
    final R result = (R)propertyAccessor.getBean();
    final CratePersistentProperty idProperty = entity.getIdProperty();
    final CratePersistentProperty versionProperty = entity.getVersionProperty();
    
    if(entity.hasIdProperty()) {
    	Object idValue = getValueInternal(idProperty, source, result);
    	propertyAccessor.setProperty(idProperty, idValue);
    }
    
    if(entity.hasVersionProperty()) {
    	Object versionValue = getValueInternal(versionProperty, source, result);
    	propertyAccessor.setProperty(versionProperty, versionValue);
    }
    
    for(CratePersistentProperty property : entity.getPersistentProperties()) {
    	// skip id and version properties as they may have potentially been set above.  
		if((idProperty != null && idProperty.equals(property)) || (versionProperty != null && versionProperty.equals(property))) {
			continue;
		}
		
		if(!source.containsKey(property.getFieldName()) || entity.isConstructorArgument(property)) {
			continue;
		}
		
		propertyAccessor.setProperty(property, getValueInternal(property, source, result));
    }
    
    entity.doWithAssociations(new AssociationHandler<CratePersistentProperty>() {
    	
      @Override
      public void doWithAssociation(final Association<CratePersistentProperty> association) {	    	  
    	  CratePersistentProperty inverseProp = association.getInverse();
    	  Object obj = getValueInternal(inverseProp, source, result);
    	  propertyAccessor.setProperty(inverseProp, obj);
      }	      
    });

    return result;
  }