If you use the first() method such as:
Car car = ofy().load().type(Car.class).filter("vin", "123456789").first().now();
Do you need to use limit(1) like this Car car = ofy().load().type(Car.class).filter("vin", "123456789").limit(1).first().now(); to make sure only one entity is loaded (instead of loading all entities that match the query)? Or will the first() method ensure only one entity will be queried for?
first() automatically applies a limit(1).
Don't be shy about navigating to the implementations in your IDE. In IntelliJ, Navigate -> Method Hierarchy is very helpful.
Related
How do you model the following restriction?
A place is popular if it has been bookmarked by 2 or more than 2 users.
Here the corresponding uml diagram:
uml
I tried several ways, for example:
context place inv: place.popular = (self.user.place.popular>=2)
but nothing worked well...
The constraint that you expressed is an interesting start but does not work because self.user in the place context is a collection. Your expression moreover attempts to use popular as if it were an integer.
If there would be an unambiguous user, you’d just need to check its size():
context place inv:
place.popular = (self.user->size()>1)
Unfortunately, there are two associations with User: one for the favorites (bookmarks) and for for historic (past visits whether they appreciated or not). This makes that expression ambiguous. To disambiguate, in absence of a role name (name at the association end), you’ll need to qualify the user with the association name:
context place inv:
place.popular = (self.favorites::user->size()>1)
(Btw, in case of absence of association name, you'd need to use the default name A_place_user instead of favorites).
See also section 7.5.3 of the OCL specifications for more information about navigating associations.
Edit: more complex navigations**:
You could also navigate to properties of associated classes. It works like the navigation above, but with the help of the collect() operation. You can then perform collection oprations such as sum()
context route inv:
self.totalDistance = self.step->collect(distanceFromPreviousStep)->sum()
Navigating to a specific object in a collection of linked objects is more delicate. In the case of the steps, we see that the association is ordered (by the way, it should be {ordered} and not «ordered»). This allows to use last() to get the last element in the given order:
context route inv:
self.destination::place = self.step->last().place
I am in need of grabbing a few fields of an entity, running them through some processing, and returning the processed data. I am wondering if it is possible to call the getters of the Entity for which the custom repository is being built inside that custom repository? The only way I thought of so far seems like it would create an infinite loop by calling the entity's repository, which would include a call to the very custom repository being used as well.
I can write the actual queries, but I figured it it would be cleaner to access the data through existing methods, then why not?
Update: So I built a method in the custom repository that I pass the entity object to that I want to work with. Seems a little weird that I would have to pass the entity to it's own custom repository so that it would know what to act on, but I can't seem to find any other way. So in my Controller right now I am calling the entity, then calling up the repository for the entity, and passing the previously called entity to the repository. Is that right?
$user = $this->get('security.context')->getToken()->getUser();
$user_repository = $this->getDoctrine()->getRepository('AppBundle:User');
$profiles = $user_repository->getAllUsersProfiles($user);
It turns out I had the whole concept of Custom Repositories incorrect. I was using them to store methods that would pull out data relevant to the entity, but only relevant in the sense that the entity was being used to filter something else.
Prior to this epiphany my User Custom Repository had methods like getAllUsersProfiles($user) and getAllUsersCampaigns($user). My previously incorrect understanding was that because the User entity was the thing that was central to filtering the Profiles and Campaigns, that these belonged in the User Custom Repository.
What I have now come to understand is that getAllUserProfiles($user) belongs in the Profiles Custom Repository, and would be more appropriately named getAllByUser($user). Now when I need to use it, I pull up the Profiles Repository and call the appropriate method:
$profile_repository = $this->getDoctrine()->getRepository('AppBundle:Profile');
$all_profiles = $profile_repository->getAllByUser($user);
I have some personal data structure mixed with "standard fields". I would like to avoid the manual work on simple fields (with datastore native API):
toPersist.setProperty("field1", value1);
toPersist.setUnindexedProperty("field2", value2);
but I still want to get the prefilled Entity instance toPersist so I can add my own #Ignore fields my self
For example:
Entity filled = OfyService.ofy().save().entity(this).fill();
filled.setProperty("mySpecialField", jsonValue);
//...
// I want to save my entities alone
datastore.put( filled );
reversely I'd like to get the Entity object representing each entry in a load() call.
Is this possible? or do I have to dive into Objectify code to hack it?
thanks for your answers
I don't follow your question exactly, but I'm pretty sure what you're looking for are the #OnLoad and #OnSave annotations. You add them to methods within your entity classes, and those methods will be called just after an entity is loaded, or just before one is saved, respectively. The documentation for them is here.
Edit:
After your comments (below) I now understand what you are trying to accomplish. Yes, Objectify supports this (though I have never tried it myself). You want to use the Saver.toEntity() and Loader.fromEntity() methods. It appears you can use them like this:
// Use Objectify to convert a POJO into an Entity
Entity filled = ofy().save().toEntity(myPojo);
// Use Objectify to convert an Entity into a POJO
Object pojoCopy = ofy().load().fromEntity(filled);
I'm having a design issue in my project, related to where put some business logic.
I have three entities, Event, TicketOrder and Ticket. One Event has a lot of TicketOrders and one TicketOrder has a lot of Tickets.
In my template, I have to show how many tickets an Event has. I've thinking of the best approach to achieve this and didn't get a good solution. I've tried this:
1) Create a private member 'ticketsCount' in Event entity, with setTicketsCount and getTicketsCount method. Create a 'loadTicketsCount' method with a LifeCycleCallback 'PostLoad', to access the TicketRepository method 'findByEvent'. This was impossible because I can't access repository in an entity class.
2) In the action that will be used to display the Event, I can access Ticket Repository and set event 'ticketsCount' property manually. I don't know if it is a good approach because if my action is listing a lot of events I'll have to loop trough all events and make a repository call to each of then.
I really don't know the best approach to achieve this and will really appreciate if someone can help me.
Thanks! ;)
When you use findAll, findBy or findBy* methods of doctrine entity repository, a simple php array is returned containing the entity objects.
The array class implements countable interface. So using twigs length filter
{{ ticketOrder.tickets|length }}
you perform a simple php count() on the array.
Actually it makes now sense to perform a count query, because you already have the result in memory. So it seems more efficient to count the result and retrieve it from memory, because when you access associations they are completely loaded into memory.
However associations between entities can get pretty large. So imagine you have associations with hundred thousands of entities. You won't those entites to be loaded all together and kept in memory all the time. So in Doctrine 2.1 you can annotate an association as Extra Lazy. If you do so in your case a count query is performed when you call the above twig filter. But the result is not kept in memory.
http://docs.doctrine-project.org/en/2.0.x/tutorials/extra-lazy-associations.html
According to your latest comment:
I can imagine one way to do this. In a template you can call a controller's action with the render statement like
{% render YourMainBundle:getTickets with { 'event_id' : event.id } %}
and in this action you can call a query that looks for all tickets associated to the certain event. This action has to return html, e.g. an template filled with data.
I have two entities that represent users (User) and friendship requests (FriendshipRequest). There is a oneToMany relationship between User and FriendshipRequest, so Doctrine creates a method that is called getFriendshipRequests() in the class User. This is ok, but FriendshipRequest has an attribute that is called status, so I would like that the User class could filter the friendship requests associated to it attending to their status. I have read Doctrine documentation, and I found out this:
Natively you can’t filter associations in 2.0 and 2.1. You should use
DQL queries to query for the filtered set of entities.
According to this, I suppose that I should create a FriendshipRequest repository and create a method called "findByStatusAndUser" (or something like that), but I think that's a crappy solution.
I would like to have a method in the User entity, like getPendingStatusRequests(). Is this possible? If it isn't, what would be the best solution?
As of Doctrine 2.3 you can use matching and Criteria.
Then you could use getPendingStatusRequests() in User entity just like you wanted.
For your example the code would look like this:
public function getPendingStatusRequests()
{
$criteria = Criteria::create(); //don't forget to use Doctrine\Common\Collections\Criteria;
$criteria->where(Criteria::expr()->eq('status', 1));
return $this->friendshipRequests->matching($criteria);
}
I think that "getPendingRequestsForUser($user)" method in the FriendshipRequest repository should be a good solution. Inside this method you just need to create an appropriate DQL.
This is a good solution, because all of the logic should be moved to repositories, leaving entities as small and clean as possible.
UPD: Also, you could use findBy method, as described here, ex:
$pendingRequests = $em->getRepository('MyBundle:FriendshipRequest')->findBy(
array('user' => $user->getId(), 'status' => 1)
);
But for me, first method is preferred.
You can certainly add getPendingStatusRequests() to user and then have it cycle through all the friendship requests and only return those with the appropriate status.
The only potential problem is that all of the friendship requests will always be loaded including those you don't need. It is up to you to decide if this is a real problem or not. It might be that once a friendship request is processed then it is removed so a user won't have many requests at any given time.
If you do want to avoid loading all the requests then make a query and use the WITH expression on your join clause. Something like:
$qb->leftJoin('user.friendshipRequests','request',
Expr\Join::WITH, $qb->expr()->eq('request.status', $qb->expr()->literal('Pending')));
And since you are using S2 I would not fool around with repositories. Just make a service called UserManager, inject the entity manager, and give it a method called loadUserWithPendingFriendshipRequests.