Introduction
I'm working on a symfony3 project and I have a lot of different "types" for certain entities. What I mean by this is that, I have a TypeUser, TypeEvent, TypeMeeting tables.
These tables will only have an id and a label.
Problem:
When using doctrine, I can link 1 entity to 1 table using the anotations, like so:
/**
* #ORM\Entity
* #ORM\Table(name="TypeUser")
*/
However, I would like this part to be completely generic. How can I specify the Table name depending on the type I need?
Is there another alternative when using Doctrine other than the annotations to make this possible?
I would really like to avoid making n entities for n tables, when they are very similar in name and in structure.
Question:
Is it possible to make one generic entity to match a specific TypeXXXX table, to reduce redundancy? If so how would I go about doing it?
Similar Doctrine 2.1 - Map entity to multiple tables
Symfony book on doctrine
Related
I read about some arguments on Soft delete vs. Archive table which led me to this question.
I thought I could implement an entity Product which is mapped to two identical tables Product and ArchivedProduct, but there is a known limitation of Doctrine 2
Mapping many tables to one entity
It is not possible to map several equally looking tables onto one entity. For example, if you have a production and an archive table of a certain business concept then you cannot have both tables map to the same entity.
So I thought I could use two entities, Product and ArchivedProduct, that are mapped to the same table, but it led to another problem that the One-to-Many reference $products in the entity Category should be mapped to two different entities.
Should I use Inheritance Mapping on Product and ArchivedProduct? What's the best practice of Archive table with Symfony 4 and Doctrine 2?
I'm using the most recent versions of ZF2 and doctrine2 orm in a project.
What I want to achieve, is a generic class "Comment" that has a relation to another entity. This entity could be from various classes "Post", "Image" aso., depending on what the comment should be related to.
The idea was to have one table for all comments and a column that defines the type of related entity, just like using the discriminator mapping.
Problem with the discriminator is that I have to create different classes using extends, for every use case. This does not seem efficient as I will have to create quite a lot of subclasses to reflect all relations needed.
I would like to use just the base class of Comment and have one or two column(s) defining the relation like "Post:25" (target class and id in one column) or "Post" | "25" (target class an id in separate columns).
Is this possible in doctrine or is there a besser way of dealing with this?
I've been thrown a 'can it be done in Doctrine' type question by my supervisor, and while I've been able to do some of it with external 'Mapper' objects, I'm wondering if there might be any way to fake-out the ORM to do it within Doctrine itself.
Essentially, the thing we are interested in doing is cutting down database clutter. We have a number of tables containing distinct properties or item sets in various categories and then a whole bunch of link-tables tying them to other properties or item sets. For example
We have a couple of tables such as 'Materials' and 'PaperTypes' which describe various Material and Paper options for our products. We then group these into 'MaterialCollections' and 'PaperFamilies' respectively. Then there has to be a one-to-many link table between MaterialCollection/Materials and PaperFamilies/PaperTypes respectively. Repeat these types of relationships a couple dozen more times and you see where our DB is starting to clutter up.
The link tables themselves are nothing more than a number of entries including multiple records with the PrimaryId from the parent table (collections/families) and unique-per-parent PrimaryId's from the sub-table (materials/papertypes). Link tables could be named something like MaterialCollectionsMaterials and PaperFamilyPaperTypes for example.
The idea was to get rid of this slew of link tables by using an abstract 3-table structure as follows:
Lists (consisting of a unique ListId, a ListName and a TypeId)
Types (consisting of a unique TypeId, a TypeName and an EntityName)
ListXref (consisting of ListIds and memberId which points to the primaryId from the Entity designated in the list type)
Multiple lists can exist for a given type, but the Xref pairs are unique. Different Types can also point to the same Entity. (e.g. there may be more than one type of Material list defined)
The 'ListName' would be the equivalent of the parent TableNames above and would allow for eliminating two of the tables in those relationships. So the records in 'MaterialCollections' would now instead be records in the List table of TypeName "MaterialCollection". The records that would have been in a link table (such as MaterialCollectionsMaterials) would now instead be pointed to from ListXRef.
As stated, I've gotten a basic mapper to make this work for rather basic list creation. But what I'm wondering is if there is any way to create Entities or things that behave like Doctrine Entities to establish the abstract relationships between a given list/listtype and the table referenced by EntityName and the corresponding memberIds?
In other words, it would be really nice if I had some means by which I could produce something that had the bulk of functionality of a Doctrine Entity which could be retrieved from the Service Manager or something like it that would behave (have similar properties/functions) like a Doctrine Entity.
I tried adding a wrapper object in the Entity tree that my mappers could try to retrieve which was basically an inherited version of the Xref entity with a few alias functions, but it can't be retrieved with the Entity manager.
Any help is appreciated.
P.S. While it is not a priority at the moment, longer term I also want to really throw a wrench into the works by trying to have some lists be capable of pointing back to the records produced by other lists. So, for example, a List "ProductXMaterials" of type "ProductMaterials" might point to some but not all results of "MaterialCollections". But I'll worry about this one later.
Well, Doctrine can't generate "pseudo entity classes" but you can.
First you need to hook into the Doctrine "loadClassMetadata" event.
Inside, you generate your entity classes and configuration from code on the fly and dump them into a specified directory (in the cache for example) maintaining the doctrine convention naming but with a custom namespace. For example : "AutoGeneratedNamespace\Entities"
So let's say you need to have a dynamic entity generated for an entity with name: "TmpUser", and you're using "yml" instead of annotations
<?php
namespace Example;
use Doctrine\ORM\Event\LoadClassMetadataEventArgs;
class DoctrineEventListener
{
/**
* Invoked on Doctrine loadClassMetadata event
*
* #var Doctrine\ORM\Event\LoadClassMetadataEventArgs
**/
public function loadClassMetadata(LoadClassMetadataEventArgs $args)
{
$em = $args->getEntityManager();
$metadata = $args->getClassMetadata();
$factory = $em->getMetadataFactory();
$name = 'AutoGeneratedNamespace\Entities\TmpUser';
$tmpDirectory = '/path/to/cache/generated-classes';
// current class metadata is the same as the one we need. this means we already generated it
if($metadata->getName() == $name || $factory->hasClassMetadata($name)) {
return;
}
/**
Generate your class here and dump it into the cache directory with the name: TmpUser.php
(If you're using "yml" instead of annotations also create the TmpUser.orm.yml configuration and dump it in the same directory)
**/
// create a metadata for the newly created class
$metadata = $factory->newClassMetadataInstance($name);
// Register metadata so doctrine knows about it
$factory->setMetadataFor($name, $metadata);
}
}
Finally, you tell Doctrine to look for entities inside the cache directory as well using the configuration: (This is taken from the Symfony documentation so if you're not using Symfony it may vary a bit but you can find the precise configuration in the Doctrine docs)
doctrine:
orm:
mappings:
MyGeneratedEntitiesUniqueMappingsKey:
type: yml
dir: '/path/to/cache/generated-classes'
is_bundle: false
prefix: "AutoGeneratedNamespace\Entities"
alias: GeneratedEntities
I have a problem with 61 join table limit of mysql. I have 57+ different classes extending Base Class which contain association to comments, likes, tags. And MySQL is crashing when i get most commented. Doctrine has to join whole discriminator maps and comments itself and order by COUNT(comments).
Is there way to fix that ?
And is there another way to achieve comments for different types of entities without inheritance and copying same association all over again?
Here is sample schema of Entities. When I want to add new Entity Type with comments,likes I just extends BaseClass to receive these features.
If I understand correctly what you're trying to do is have many different entity types which can be commented on.
First thing to do would be to step back from Doctrine and thing about the simplest table structure you would need to accomplish this.
Something like this may suffice:
Comments
_______________________
| id | type | entity_id |
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
It is nice in Doctrine to have bi-directional relationships in your base class for convenience but sometimes they are not the best choice. Maybe it would simplify your architecture to perform a query directly on the comments table by entity type and id.
You may also want to consider removing the Base class and having each entity be standalone.
Since a blog post can exist in a context where it does not have comments (on a blog that doesn't allow commenting for example) then $blog->getComments() wouldn't make much sense.
Making this change you could do something like this instead:
$comments = $commentsRepository->findCommentsForEntity($entity);
$commentsCount = count($comments);
and the repository could generate the needed query passing the entity as the entity_id parameter and setting the required comment type based on the entity type.
I'm trying to figure out the correct way to map my three entities together. I have a "HouseType", a "Resource" and a HouseType can have multiple Resources (with an integer indicating how many of that resource they have). So I have three tables, the house_type, resource and house_type_resource (with house_type_id, resource_id, and num).
I can't figure out what type of association mapping I should do. I'm reading this page: http://docs.doctrine-project.org/en/latest/reference/association-mapping.html but I don't see one that's like mine, where I have a third entity to represent the join table, because it has a specific property that needs to be included (the num). It's sort of like the "Many-To-Many, Unidirectional" but I need that third Entity mapped in there. I see the note at the end about doing an Association class but I don't see any more info on that.
Once you start adding extra columns, Doctrine stops treating it as a pure many-to-many relationship because there is extra data, and this data should be managed with an entity. You should create a new entity called HouseTypeResource, then create one-to-many relationships with this inside your HouseType and Resource entities.