I'm having my first go with Frames and my Java is pretty rusty. I'm stuck on writing information through Frames into the database. I've been following the docs and have a Person interface.
public interface Person {
#Property("name")
public String getName();
#Adjacency(label="knows")
public Iterable<Person> getKnowsPeople();
#Adjacency(label="knows")
public void addKnowsPerson(final Person person);
#GremlinGroovy("it.out('knows').out('knows').dedup") //Make sure you use the GremlinGroovy module! #1
public Iterable<Person> getFriendsOfAFriend()
}
Which is taken from the docs.
I can use this simple code to get data out of the graph.
TinkerGraph graph = TinkerGraphFactory.createTinkerGraph(); //This graph is pre-populated.
FramedGraphFactory factory = new FramedGraphFactory(new GremlinGroovyModule()); //(1) Factories should be reused for performance and memory conservation.
FramedGraph framedGraph = factory.create(graph); //Frame the graph.
Person person = framedGraph.getVertex(1, Person.class);
person.getName(); // equals "marko"
What I'd like to know is how I would create a new Person object and write it to the graph. Because Person is only an interface I can't do:
Person person2 = new Person();
person2.setName("John");
person2.setAge(36);
framedGraph.addVertex(person2);
So I've tried a PersonImpl class which implements Person and added the following code
PersonImpl johnBoy = new PersonImpl();
johnBoy.setName("John");
johnBoy.setAge(36);
johnBoy.addKnowsPerson(person);
person.addKnowsPerson(johnBoy);
However I'm getting the following NullPointer and I'm now really stuck. I was hoping someone might possibly be able to help me.
Exception in thread "main" java.lang.NullPointerException
at com.tinkerpop.blueprints.impls.tg.TinkerGraph.addEdge(TinkerGraph.java:331)
at com.tinkerpop.frames.FramedGraph.addEdge(FramedGraph.java:310)
at com.tinkerpop.frames.annotations.AdjacencyAnnotationHandler.addEdges(AdjacencyAnnotationHandler.java:87)
at com.tinkerpop.frames.annotations.AdjacencyAnnotationHandler.processVertex(AdjacencyAnnotationHandler.java:53)
at com.tinkerpop.frames.annotations.AdjacencyAnnotationHandler.processElement(AdjacencyAnnotationHandler.java:26)
at com.tinkerpop.frames.annotations.AdjacencyAnnotationHandler.processElement(AdjacencyAnnotationHandler.java:15)
at com.tinkerpop.frames.FramedElement.invoke(FramedElement.java:89)
at com.sun.proxy.$Proxy4.addKnowsPerson(Unknown Source)
at com.elecrticdataland.utility.TinkerTest.main(TinkerTest.java:45)
With many thanks,
John
You can't create a Person except by way of proxy. In other words, you can't use a concrete implementation of that interface, it has to be constructed dynamically by the FramesGraph.
You have the code to create a Person here:
FramedGraph framedGraph = factory.create(graph); //Frame the graph.
Person person = framedGraph.getVertex(1, Person.class);
person.getName(); // equals "marko"
Without that, the created Person implementation will not know anything about the underlying and injected Graph instance given to factory.create()
Related
I'm trying to implement custom cloning in my solution, i followed the instructions as in the documentation, and i encountered a roadblock in the form of this exception : The entity was never added to this ScoreDirector. Maybe that specific instance is not in the return values of the PlanningSolution's entity members. I know that this is not true because before the custom cloning, this exception wasn't thrown.
My planningClone method is setup like this :
#Override
public Solution planningClone() {
Solution clonedSolution = new Solution();
clonedSolution.id = id;
clonedSolution.code = code;
clonedSolution.score = score;
clonedSolution.field1 = field1;
clonedSolution.field2 = field2;
...............
clonedSolution.fieldN = fieldN;
List<PlanningEntity1> clonedPlanningEntity1List= new ArrayList<PlanningEntity1>(planningEntity1List.size());
List<PlanningEntity2> clonedPlanningEntity2List= new ArrayList<PlanningEntity2>(planningEntity1List.size());
for (PlanningEntity1 planningEntity: planningEntity1List) {
clonedPlanningEntity1List.add(planningEntity.clone());
}
for (PlanningEntity2 planningEntity: planningEntity2List) {
clonedPlanningEntity1List.add(planningEntity.clone());
}
clonedSolution.planningEntity1List = clonedPlanningEntity1List;
clonedSolution.planningEntity2List = clonedPlanningEntity2List;
return clonedSolution;
{
The clone method for my planning entities is implemented through the Java interface Cloneable:
protected PlanningEntity clone() {
try {
return (PlanningEntity) super.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
return null;
}
Just to be sure, i checked every entity instance and their collections to make sure my cloning was working correctly, and it in fact is.
What step am i missing here?
If there is one planning entity pointing to another planning entity from a different class or maybe pointing to a list, than the cloning process needs to take care of the references for those planning entities so they point to the cloned objects.This is something that the default cloning process is doing without a problem, and thus leaving the solution in a consistent state. It even updates the Lists of planning entity instances in the parent planning entities correctly (covered by the method "cloneCollectionsElementIfNeeded" from the class "FieldAccessingSolutionCloner" from the OptaPlanner core).
So for example if we have the next two planning entity classes
#PlanningEntity
public class ParentPlanningEntityClass{
List<ChildPlanningEntityClass> childPlanningEntityClassList;
}
#PlanningEntity
public class ChildPlanningEntityClass{
ParentPlanningEntityClass parentPlanningEntityClass;
}
The "parentPlanningEntityClass" variable needs to be set to point to the cloned object. When it comes to the list "childPlanningEntityClassList" it first needs to be created from scratch with "new ArrayList();" so that both the working and new best solution (the one that is currently getting cloned) don't point to the same list. At the end the newly created list needs to be filled with the cloned objects.
I am implementing an algorithm similar to the NurseRoster one in OptaPlanner. I need to implement a rule in drools that check if the Employee cannot work more days than the number of days in his contract. Since i couldn't figure out how to make this in drools, i decided to write it as a method in a class, and then use it in drools to check if the constraint has been broken. Since i needed a List of ShiftAssignments in the Employee class, i needed to use an #InverseRelationShadowVariable that updated that list automatically an Employee got assigned to a Shift. Since my Employee now has to be a PlanningEntity, the error The entity was never added to this ScoreDirector appeared. I believe the error is caused by my ShiftAssignment entity, which has a #ValueRangeProvider of employees that can work in that Shift. I think this is due to the fact that ScoreDirector.beforeEntityAdded and ScoreDirector.afterEntityAdded were never called, hence the error. For some reason when i removed that range provider from ShiftAssignment and put it on NurseRoster which is the #PlanningSolution, it worked.
Here is the code:
Employee:
#InverseRelationShadowVariable(sourceVariableName = "employee")
public List<ShiftAssignment> getEmployeeAssignedToShiftAssignments() {
return employeeAssignedToShiftAssignments;
}
ShiftAssignment:
#PlanningVariable(valueRangeProviderRefs = {
"employeeRange" }, strengthComparatorClass = EmployeeStrengthComparator.class,nullable = true)
public Employee getEmployee() {
return employee;
}
// the value range for this planning entity
#ValueRangeProvider(id = "employeeRange")
public List<Employee> getPossibleEmployees() {
return getShift().getEmployeesThatCanWorkThisShift();
}
NurseRoster:
#ValueRangeProvider(id = "employeeRange")
#PlanningEntityCollectionProperty
public List<Employee> getEmployeeList() {
return employeeList;
}
And this is the method i use to update that listOfEmployeesThatCanWorkThisShift:
public static void checkIfAnEmployeeCanBelongInGivenShiftAssignmentValueRange(NurseRoster nurseRoster) {
List<Shift> shiftList = nurseRoster.getShiftList();
List<Employee> employeeList = nurseRoster.getEmployeeList();
for (Shift shift : shiftList) {
List<Employee> employeesThatCanWorkThisShift = new ArrayList<>();
String shiftDate = shift.getShiftDate().getDateString();
ShiftTypeDefinition shiftTypeDefinitionForShift = shift.getShiftType().getShiftTypeDefinition();
for (Employee employee : employeeList) {
AgentDailySettings agentDailySetting = SearchThroughSolution.findAgentDailySetting(employee, shiftDate);
List<ShiftTypeDefinition> shiftTypeDefinitions = agentDailySetting.getShiftTypeDefinitions();
if (shiftTypeDefinitions.contains(shiftTypeDefinitionForShift)) {
employeesThatCanWorkThisShift.add(employee);
}
}
shift.setEmployeesThatCanWorkThisShift(employeesThatCanWorkThisShift);
}
}
And the rule that i use:
rule "maxDaysInPeriod"
when
$shiftAssignment : ShiftAssignment(employee != null)
then
int differentDaysInPeriod = MethodsUsedInScoreCalculation.employeeMaxDaysPerPeriod($shiftAssignment.getEmployee());
int maxDaysInPeriod = $shiftAssignment.getEmployee().getAgentPeriodSettings().getMaxDaysInPeriod();
if(differentDaysInPeriod > maxDaysInPeriod)
{
scoreHolder.addHardConstraintMatch(kcontext, differentDaysInPeriod - maxDaysInPeriod);
}
end
How can i fix this error?
This has definitely something to do with the solution cloning that is happening when a "new best solution" is created.
I encountered the same error when i implemented custom solution cloning. In my project i have multiple planning entity classes and all of them have references to each other (either a single value or a List). So when solution cloning is happening the references need to be updated so they can point to the cloned values. This is something that the default cloning process is doing without a problem, and thus leaving the solution in a consistent state. It even updates the Lists of planning entity instances in the parent planning entities correctly (covered by the method "cloneCollectionsElementIfNeeded" from the class "FieldAccessingSolutionCloner" from the OptaPlanner core).
Just a demonstration what i have when it comes to the planning entity classes:
#PlanningEntity
public class ParentPlanningEntityClass{
List<ChildPlanningEntityClass> childPlanningEntityClassList;
}
#PlanningEntity
public class ChildPlanningEntityClass{
ParentPlanningEntityClass parentPlanningEntityClass;
}
At first i did not update any of the references and got the error even for "ChildPlanningEntityClass". Then i have written the code that updates the references. When it comes to the planning entity instances that were coming from the class "ChildPlanningEntityClass" everything was okay at this point because they were pointing to the cloned object. What i did wrong in the "ParentPlanningEntityClass" case was that i did not create the "childPlanningEntityClassList" list from scratch with "new ArrayList();", but instead i just updated the elements of the list (using the "set" method) to point at the cloned instances of the "ChildPlanningEntityClass" class. When creating a "new ArrayList();", filling the elements to point to the cloned objects and setting the "childPlanningEntityClassList" list everything was consistent (tested with FULL_ASSERT).
So just connecting it to my issue maybe the list "employeeAssignedToShiftAssignments" is not created from scratch with "new ArrayList();" and elements instead just get added or removed from the list. So what could happen (if the list is not created from scratch) here is that both the working and the new best solution (the clone) will point to the same list and when the working solution would continue to change this list it would corrupt the best solution.
There’s something which I am doing that is working, but I think it can probably be done a lot better (and therefore, with more maintainability).
I am using Ninject to inject various things into a controller. The problem which I needed to solve is that the DbContext for each repository needed to be the same. That is, the same object in memory.
Whilst, the following code does achieve that, my Ninject common config file has started to get quite messy as I have to write similar code for each controller:
kernel.Bind<OrderController>().ToMethod(ctx =>
{
var sharedContext = ctx.Kernel.Get<TTSWebinarsContext>();
var userAccountService = kernel.Get<UserAccountService>();
ILogger logger = new Log4NetLogger(typeof(Nml.OrderController));
ILogger loggerForOrderManagementService = new Log4NetLogger(typeof(OrderManagementService));
var orderManagementService = new OrderManagementService(
new AffiliateRepository(sharedContext),
new RegTypeRepository(sharedContext),
new OrderRepository(sharedContext),
new RefDataRepository(),
new WebUserRepository(sharedContext),
new WebinarRepository(sharedContext),
loggerForOrderManagementService,
ttsConfig
);
var membershipService = new MembershipService(
new InstitutionRepository(sharedContext),
new RefDataRepository(),
new SamAuthenticationService(userAccountService),
userAccountService,
new WebUserRepository(sharedContext)
);
return new OrderController(membershipService, orderManagementService, kernel.Get<IStateService>(), logger);
}).InRequestScope();
Is there a neater way of doing this?
Edit
Tried the following code. As soon as I make a second request, an exception is chucked that the DbContext has already been disposed.
kernel.Bind<TTSWebinarsContext>().ToSelf().InRequestScope();
string baseUrl = HttpRuntime.AppDomainAppPath;
kernel.Bind<IStateService>().To<StateService>().InRequestScope();
kernel.Bind<IRefDataRepository>().To<RefDataRepository>().InRequestScope().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
var config = MembershipRebootConfig.Create(baseUrl, kernel.Get<IStateService>(), kernel.Get<IRefDataRepository>());
var ttsConfig = TtsConfig.Create(baseUrl);
kernel.Bind<MembershipRebootConfiguration>().ToConstant(config);
kernel.Bind<TtsConfiguration>().ToConstant(ttsConfig);
kernel.Bind<IAffiliateRepository>().To<AffiliateRepository>().InRequestScope().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
kernel.Bind<IWebinarRepository>().To<WebinarRepository>().InRequestScope().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
kernel.Bind<IWebUserRepository>().To<WebUserRepository>().InRequestScope().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
kernel.Bind<IOrderRepository>().To<OrderRepository>().InRequestScope().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
kernel.Bind<IInstitutionRepository>().To<InstitutionRepository>().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
kernel.Bind<IUserAccountRepository>().To<DefaultUserAccountRepository>().InRequestScope();
kernel.Bind<IRegTypeRepository>().To<RegTypeRepository>().InRequestScope().WithConstructorArgument("context", kernel.Get<TTSWebinarsContext>());
kernel.Bind<UserAccountService>().ToMethod(ctx =>
{
var userAccountService = new UserAccountService(config, ctx.Kernel.Get<IUserAccountRepository>());
return userAccountService;
});
kernel.Bind<IOrderManagementService>().To<OrderManagementService>().InRequestScope();
//RegisterControllers(kernel, ttsConfig);
kernel.Bind<AuthenticationService>().To<SamAuthenticationService>().InRequestScope();
kernel.Bind<IMembershipService>().To<MembershipService>().InRequestScope();
There's something about InRequestScope I'm misunderstanding.
Edit:
.InRequestScope() will ensure everything which gets injected that binding will receive exactly the same instance when during injection (creation) the HttpContext.Current is the same. That means when a client makes a request and the kernel is asked to provide instances with .InRequestScope(), it will return the same instance for the exact same request. Now when a client makes another request, another unique instance will be created.
When the request ends, ninject will dispose the instance in case it implements IDisposable.
However consider the following scenario:
public class A
{
private readonly DbContext dbContext;
public A(DbContext dbContext)
{
this.dbContext = dbContext;
}
}
and binding:
IBindingRoot.Bind<DbContext>().ToSelf().InRequestScope();
IBindingRoot.Bind<A>().ToSelf().InSingletonScope();
You got yourself a major problem. There's two scenarios how this can pan out:
You are trying to create an A outside of a request. It will fail. Instantiating the DbContext, ninject will look for HttpContext.Current - which is null at the time - and throw an Exception.
You are trying to create an A during a request. Instantiating will succeed. However, When you try to use some functionality of A (which is accessing DbContext in turn) after the request or during a new request, it will throw an ObjectDisposedException
To sum it up, an ObjectDisposedException when you access the DbContext can only be caused by two scenarios:
-you ar disposing the DbContext (or some component which in turn disposes the DbContext) before the request is over.
-you are keeping a reference to the DbContext (again, or to some component which in turn references the DbContext) across request boundaries.
That's it. Nothing complicated about this, but your object graph.
So what would help is drawing an object graph. Start from the root / request root. Then when you're done, start from the DbContext and check who's calling Dispose() on it. If there is no usage inside your code, it must be Ninject who's cleaning up when the request ends. That means, you need to check all references to the DbContext. Someone is keeping a reference across requests.
Original Answer:
You should look into scopes: https://github.com/ninject/ninject/wiki/Object-Scopes
Specifically, .InRequestScope() - or in case that is not appliccable to your problem - .InCallScope() should be interesting to you.
As you are already using .InRequestScope() for the original binding, i suggest that binding the shared context type also .InRequestScope() should be sufficient. It means every dependency of the OrderController will receive the same webinar context instance. Furthermore, if someone else in the same request wants to get a webinar context injected, he will also get the same instance.
You should look into scopes: https://github.com/ninject/ninject/wiki/Object-Scopes
Specifically, .InRequestScope() - or in case that is not appliccable to your problem - .InCallScope() should be interesting to you.
As you are already using .InRequestScope() for the original binding, i suggest that binding the shared context type also .InRequestScope() should be sufficient. It means every dependency of the OrderController will receive the same webinar context instance. Furthermore, if someone else in the same request wants to get a webinar context injected, he will also get the same instance.
After lots of reading about serialization, I've decided to try to create DTOs. After more reading, I decided to use AutoMapper.
What I would like to do is transform the parent (easy enough) and transform the entity properties if they've been initialized, which I've done with ValueResolvers like below (I may try to make it generic once I get it fully working). This part works.
public class OrderItemResolver : ValueResolver<Order, OrderItem>
{
protected override OrderItem ResolveCore(Order source)
{
// could also use NHibernateUtil.IsInitialized(source.OrderItem)
if (source.OrderItem is NHibernate.Proxy.INHibernateProxy)
return null;
else
return source.OrderItem;
}
}
}
When I transform the DTO back to an entity, for the entities that weren't initialized, I want to create a proxy so that if the entity wants to access it, it can. However, I can't figure out how to create a proxy. I'm using Castle if that's relevant.
I've tried a bunch of things with no luck. The below code is a mess, mainly because I've been trying things at random without knowing what I should be doing. Anybody have any suggestions?
public class OrderItemDTOResolver : ValueResolver<OrderDTO, OrderItem>
{
protected override OrderItem ResolveCore(OrderDTO source)
{
if (source.OrderItem == null)
{
//OrderItem OrderItem = new ProxyGenerator().CreateClassProxy<OrderItem>(); // Castle.Core.Interceptor.
//OrderItem OrderItem = new ProxyGenerator().CreateClassProxy<OrderItem>();
//OrderItem.Id = source.OrderItemId;
//OrderItem OrderItem = new OrderItem();
//var proxy = new OrderItem() as INHibernateProxy;
//var proxy = OrderItem as INHibernateProxy;
//return (OrderItem)proxy.HibernateLazyInitializer
//ILazyInitializer proxy = new LazyInitializer("OrderItem", OrderItem, source.OrderItemId, null, null, null, null);
//return (OrderItem)proxy;
//return (OrderItem)proxy.HibernateLazyInitializer.GetImplementation();
//return OrderItem;
IProxyTargetAccessor proxy = new Castle.Core.Interceptor.
var initializer = new LazyInitializer("OrderItem", typeof(OrderItem), source.OrderItemId, null, null, null, null);
//var proxyFactory = new SerializableProxyFactory{Interfaces = Interfaces, TargetSource = initializer, ProxyTargetType = IsClassProxy};
//proxyFactory.AddAdvice(initializer);
//object proxyInstance = proxyFactory.GetProxy();
//return (INHibernateProxy) proxyInstance;
return null;
//OrderItem.Id = source.OrderItemId;
//return OrderItem;
}
else
return OrderItemDTO.Unmap(source.OrderItem);
}
}
Thanks,
Eric
Maybe I over complicated it. This seems to work. Anybody see any issues with it?
public class OrderItemDTOResolver : ValueResolver<OrderDTO, OrderItem>
{
protected override OrderItem ResolveCore(OrderDTO source)
{
if (source.OrderItem == null)
return NHibernateSessionManager.Instance.Session.GetISession().Load<OrderItem>(source.AgencyId);
else
return OrderItemDTO.Unmap(source.OrderItem);
}
}
This may be one of those cases where the answer is "don't", or at least "you probably shouldn't". If you're mapping DTOs into NHibernate mapped objects directly you're not really using the mapped objects as domain objects, just as a fancy way to push data in and out of the database. This of course may be all you're after but having done this myself in the past I've found that it's problematic trying to use the same DTO data format in both directions. If you're going cross-process you've turned the service into a (difficult to maintain) CRUD layer. If you're in the same process you're doing unnecessary data shuffling with DTOs.
Sending DTOs out is fine, but consider projecting the data into a format more closely aligned with what the client actually needs. What you get back is better expressed in specific DTOs that express only the data needed to perform the actual action (Command objects, essentially). With a few automatic properties they're trivial to construct. You can then have a business method that performs the necessary action with only the necessary information, and that in a format suited to the action being performed. My primary use of AutoMapper (which does rock) these days is to translate incoming DTOs into types that domain methods can consume.
Also, public setters on mapped objects are undesirable because they allow the object to be manipulated by any code without any validation. This means any modification to them can leave them in an invalid state.
If you don't really care about the above (and it's not always applicable) the way you load individual instances does leave you open do doing many individual database loads which is a potential performance issue.
Updated: 09/02/2009 - Revised question, provided better examples, added bounty.
Hi,
I'm building a PHP application using the data mapper pattern between the database and the entities (domain objects). My question is:
What is the best way to encapsulate a commonly performed task?
For example, one common task is retrieving one or more site entities from the site mapper, and their associated (home) page entities from the page mapper. At present, I would do that like this:
$siteMapper = new Site_Mapper();
$site = $siteMapper->findByid(1);
$pageMapper = new Page_Mapper();
$site->addPage($pageMapper->findHome($site->getId()));
Now that's a fairly trivial example, but it gets more complicated in reality, as each site also has an associated locale, and the page actually has multiple revisions (although for the purposes of this task I'd only be interested in the most recent one).
I'm going to need to do this (get the site and associated home page, locale etc.) in multiple places within my application, and I cant think of the best way/place to encapsulate this task, so that I don't have to repeat it all over the place. Ideally I'd like to end up with something like this:
$someObject = new SomeClass();
$site = $someObject->someMethod(1); // or
$sites = $someObject->someOtherMethod();
Where the resulting site entities already have their associated entities created and ready for use.
The same problem occurs when saving these objects back. Say I have a site entity and associated home page entity, and they've both been modified, I have to do something like this:
$siteMapper->save($site);
$pageMapper->save($site->getHomePage());
Again, trivial, but this example is simplified. Duplication of code still applies.
In my mind it makes sense to have some sort of central object that could take care of:
Retrieving a site (or sites) and all nessessary associated entities
Creating new site entities with new associated entities
Taking a site (or sites) and saving it and all associated entities (if they've changed)
So back to my question, what should this object be?
The existing mapper object?
Something based on the repository pattern?*
Something based on the unit of work patten?*
Something else?
* I don't fully understand either of these, as you can probably guess.
Is there a standard way to approach this problem, and could someone provide a short description of how they'd implement it? I'm not looking for anyone to provide a fully working implementation, just the theory.
Thanks,
Jack
Using the repository/service pattern, your Repository classes would provide a simple CRUD interface for each of your entities, then the Service classes would be an additional layer that performs additional logic like attaching entity dependencies. The rest of your app then only utilizes the Services. Your example might look like this:
$site = $siteService->getSiteById(1); // or
$sites = $siteService->getAllSites();
Then inside the SiteService class you would have something like this:
function getSiteById($id) {
$site = $siteRepository->getSiteById($id);
foreach ($pageRepository->getPagesBySiteId($site->id) as $page)
{
$site->pages[] = $page;
}
return $site;
}
I don't know PHP that well so please excuse if there is something wrong syntactically.
[Edit: this entry attempts to address the fact that it is oftentimes easier to write custom code to directly deal with a situation than it is to try to fit the problem into a pattern.]
Patterns are nice in concept, but they don't always "map". After years of high end PHP development, we have settled on a very direct way of handling such matters. Consider this:
File: Site.php
class Site
{
public static function Select($ID)
{
//Ensure current user has access to ID
//Lookup and return data
}
public static function Insert($aData)
{
//Validate $aData
//In the event of errors, raise a ValidationError($ErrorList)
//Do whatever it is you are doing
//Return new ID
}
public static function Update($ID, $aData)
{
//Validate $aData
//In the event of errors, raise a ValidationError($ErrorList)
//Update necessary fields
}
Then, in order to call it (from anywhere), just run:
$aData = Site::Select(123);
Site::Update(123, array('FirstName' => 'New First Name'));
$ID = Site::Insert(array(...))
One thing to keep in mind about OO programming and PHP... PHP does not keep "state" between requests, so creating an object instance just to have it immediately destroyed does not often make sense.
I'd probably start by extracting the common task to a helper method somewhere, then waiting to see what the design calls for. It feels like it's too early to tell.
What would you name this method ? The name usually hints at where the method belongs.
class Page {
public $id, $title, $url;
public function __construct($id=false) {
$this->id = $id;
}
public function save() {
// ...
}
}
class Site {
public $id = '';
public $pages = array();
function __construct($id) {
$this->id = $id;
foreach ($this->getPages() as $page_id) {
$this->pages[] = new Page($page_id);
}
}
private function getPages() {
// ...
}
public function addPage($url) {
$page = ($this->pages[] = new Page());
$page->url = $url;
return $page;
}
public function save() {
foreach ($this->pages as $page) {
$page->save();
}
// ..
}
}
$site = new Site($id);
$page = $site->addPage('/');
$page->title = 'Home';
$site->save();
Make your Site object an Aggregate Root to encapsulate the complex association and ensure consistency.
Then create a SiteRepository that has the responsibility of retrieving the Site aggregate and populating its children (including all Pages).
You will not need a separate PageRepository (assuming that you don't make Page a separate Aggregate Root), and your SiteRepository should have the responsibility of retrieving the Page objects as well (in your case by using your existing Mappers).
So:
$siteRepository = new SiteRepository($myDbConfig);
$site = $siteRepository->findById(1); // will have Page children attached
And then the findById method would be responsible for also finding all Page children of the Site. This will have a similar structure to the answer CodeMonkey1 gave, however I believe you will benefit more by using the Aggregate and Repository patterns, rather than creating a specific Service for this task. Any other retrieval/querying/updating of the Site aggregate, including any of its child objects, would be done through the same SiteRepository.
Edit: Here's a short DDD Guide to help you with the terminology, although I'd really recommend reading Evans if you want the whole picture.