I have three tables "category", "product" and "product_category".
First two tables are created from two entity Category and Product.
Third table "product_category" is auto generated by framework doctrine console command.
Now I can get (fetch) product relational data (based on category id) from below query, which is fine.
$this->createQueryBuilder('p')
->leftJoin('p.category', 'c')
->select('p')
->where('c.id = :category_id')
->setParameter('category_id', 2)
->getQuery()->getSQL();
But how can I use Many-to-Many relation to Update Data?
I had Tried with several queries but its not working!!!
( I want to update all product status to inactive (2), whose category status is (2 = Inactive).
When doing a query on a table that has children. You can also just fetch the parent item, and doctrine will automatically handle the child objects. If you have a getCategory within the Product entity, it will resolve the category automatically.
Probably what you are looking for is cascading of events. of which is explained within Doctrine 2 ManyToMany cascade
Related
I have and Event and EventCategory model with a many-to-many relationship.
There are 2 event categories - past (ID of 2) and future (ID of 1).
I want to find all Events in the future via
models = Event.objects.filter(categories__slug='future')
And then update them so they are all in the past.
Should I create a list of the Event instances, then delete from the related table, and insert the instances with the new category ID - just wanted some guidance if possible, on the most efficient way to do this.
Many thanks
I am not sure if this is the most efficient solution for my needs but it works:
Find the new category I want to associate to the events (this is the "past" category)
cat = EventCategory.objects.get(pk=2)
Here are my existing relationships, where 1 is the ID of the future category
models = Event.objects.filter(categories__id=1)
for model in models:
model.categories.clear()
model.categories.add(cat)
Now all of the entires in the related table are in the past category.
I'm new to django and ORM in general, and so have trouble coming up with query which would join multiple tables.
I have 4 Models that need joining - Category, SubCategory, Product and Packaging, example values would be:
Category: 'male'
SubCategory: 'shoes'
Product: 'nikeXYZ'
Packaging: 'size_36: 1'
Each of the Model have FK to the model above (ie. SubCategory has field category etc).
My question is - how can I filter Product given a Category (e.g. male) and only show products which have Packaging attribute available set to True? Obviously I want to minimise the hits on my database (ideally do it with 1 SQL query).
I could do something along these lines:
available = Product.objects.filter(packaging__available=True)
subcategories = SubCategory.objects.filter(category_id=<id_of_male>)
products = available.filter(subcategory_id__in=subcategories)
but then that requires 2 hits on database at least (available, subcategories) I think. Is there a way to do it in one go?
try this:
lookup = {'packaging_available': True, 'subcategory__category_id__in': ['ids of males']}
product_objs = Product.objects.filter(**lookup)
Try to read:
this
You can query with _set, multi __ (to link models by FK) or create list ids
I think this should work but it's not tested:
Product.objects.filter(packaging__available=True,subcategories__category_id__in=[id_of_male])
it isn't tested but I think that subcategories should be plural (related_name), if you didn't set related_name, then subcategory__set instead od subcategories should work.
Probably subcategories__category_id__in=[id_of_male] can be switched to .._id=id_of_male.
Good morning. I have been looking all over trying to answer this question.
If you have a table that has foreign keys to another table, and you want results from both tables, using basic sql you would do an inner join on the foreign key and you would get all the resulting information that you requested. When you generate your JPA entities on your foreign keys you get a #oneToone annotation, #oneToMany, #ManyToMany, #ManyToOne, etc over your foreign key columns. I have #oneToMany over the foreign keys and a corresponding #ManyToOne over the primary key in the related table column I also have a #joinedON annotation over the correct column... I also have a basic named query that will select everything from the first table. Will I need to do a join to get the information from both tables like I would need to do in basic sql? Or will the fact that I have those annotations pull those records back for me? To be clear if I have table A which is related to Table B based on a foreign key relationship and I want the records from both tables I would join table A to B based on the foreign key or
Select * From A inner Join B on A.column2 = B.column1
Or other some-such non-sense (Pardon my sql if it is not exactly correct, but you get the idea)...
That query would have selected all column froms A and B where those two selected column...
Here is my named query that I am using....
#NamedQuery(name="getQuickLaunch", query = "SELECT q FROM QuickLaunch q")
This is how I am calling that in my stateless session bean...
try
{
System.out.println("testing 1..2..3");
listQL = emf.createNamedQuery("getQuickLaunch").getResultList();
System.out.println("What is the size of this list: number "+listQL.size());
qLaunchArr = listQL.toArray(new QuickLaunch[listQL.size()]);
}
Now that call returns all the columns of table A, but it lack's the column's of table B. My first instinct would be to change the query to join the two tables... But that kind of makes me think what is the point of using JPA then if I am just writing the same queries that I would be writing anyway, just in a different place. Plus, I don't want to overlook something simple. So what say you stack overflow enthusiasts? How does one get back all the data of joined query using JPA?
Suppose you have a Person entity with a OneToMany association to the Contact entity.
When you get a Person from the entityManager, calling any method on its collection of contacts will lazily load the list of contacts of that person:
person.getContacts().size();
// triggers a query select * from contact c where c.personId = ?
If you want to use a single query to load a person and all its contacts, you need a fetch in the SQL query:
select p from Person p
left join fetch p.contacts
where ...
You can also mark the association itself as eager-loaded, using #OneToMany(lazy = false), but then every time a person is loaded (vie em.find() or any query), its contacts will also be loaded.
I've got 2 existing models that I need to join that are non-relational (no foreign keys). These were written by other developers are cannot be modified by me.
Here's a quick description of them:
Model Process
Field filename
Field path
Field somethingelse
Field bar
Model Service
Field filename
Field path
Field servicename
Field foo
I need to join all instances of these two models on the filename and path columns. I've got existing filters I have to apply to each of them before this join occurs.
Example:
A = Process.objects.filter(somethingelse=231)
B = Service.objects.filter(foo='abc')
result = A.filter(filename=B.filename,path=B.path)
This sucks, but your best bet is to iterate all models of one type, and issue queries to get your joined models for the other type.
The other alternative is to run a raw SQL query to perform these joins, and retrieve the IDs for each model object, and then retrieve each joined pair based on that. More efficient at run time, but it will need to be manually maintained if your schema evolves.
I know conditional filters aren't yet available for queries (as per "26.1.4. Applying Filter Rules to any Query" in the Known Limitations section of the Doctrine2 manual) , so I wanted to ask the experts what their preferred solution to the following problem is:
My site has product objects that each have many reviews. The reviews have a status field. I don't want to unnecessarily pull in reviews that haven't been approved during the automatic association that Doctrine2 does so wonderfully.
My current solution/hack is to use single table inheritance (STI) with a discriminator for "status" and have an ApprovedProductReview extending the ProductReview class based on a status of "APPROVED"
I should add that I am currently simply calling
$em->find('Entities\Product', $pid);
to get my product, and Doctrine2 does all the associations automatically. Should I instead be instantiating a product by providing a DQL query?
What I'd really like is a way to override the magic that Doctrine2 provides based on the annotations, and simply be able to use DQL to lazily get the correct subset of reviews.
Suggestions?
You can use the WITH statement in DQL:
$dql = "SELECT p, r
FROM Entities\Product p
LEFT JOIN p.reviews r WITH r.status = :status
WHERE p.id = :id"
$q = $em->createQuery($dql);
$q->setParameter('id', $id);
$q->setParameter('status', $status);
$product = $q->getSingleResult();