Symfony4.1 Doctrine ManyToMany Reduce No of Queries - mysql

Question

I'm working on a project. Entity are Blog,Category,Tags. Blog and Tags are in ManyToMany Relation. My repository query to fetch data by Tags filter is.
CODE1:
/**
* #return BlogPost[]
*/
public function getAllActivePostsByTags($value, $order = "DESC", $currentPage = 1, $limit = 10)
{
$query = $this->createQueryBuilder('p')
// ->select('p','t')
->innerJoin('p.blogTags', 't')
->where('t.slug = :val')
->setParameter('val', $value)
->orderBy('p.id', $order)
->getQuery();
$paginator = $this->paginate($query, $currentPage, $limit);
return $paginator;
}
This code works fine. All the tags(No of tags in a post)are displayed correctly. But the No of DB Query is 14. Then When I uncomment select as this,
CODE2:
/**
* #return BlogPost[]
*/
public function getAllActivePostsByTags($value, $order = "DESC", $currentPage = 1, $limit = 10)
{
$query = $this->createQueryBuilder('p')
->select('p','t')
->innerJoin('p.blogTags', 't')
->where('t.slug = :val')
->setParameter('val', $value)
->orderBy('p.id', $order)
->getQuery();
$paginator = $this->paginate($query, $currentPage, $limit);
return $paginator;
}
No of Query is 9. But The Tags per Post is only one(Not displaying all the tags of a single post).
To be clear info:
It displays entire list of BlogPost.
But not all Tags of a Post.
Only one Tag per Post is shown.
Question: Is code1 is correct (No of DB Query = 14) or Do I have to tweak little bit to reduce no of DB Hits. Please guide me on this.

Answer 1

This is the expected behaviour in both cases.
Case 1) You just select the BlogPost entities. So you tell doctrine to fetch all BlogPosts that have the BlogTag that has slug = value.
The SQL query produced returns only column values from the blog_post table and so only hydrates the BlogPost entities returned, it does not hydrate the collection of BlogTags inside each BlogPost.
When you try to access the tags of a BlogPost a new query is generated to get and hydrate its collection.
That is the reason you get more queries in this case.
Case 2) You select also the filtered BlogTag entities, and doctrine hydrates(puts) only this filtered BlogTag to each BlogPost `s collection.
When you try to access the BlogTags of a BlogPost, you get the filtered one that meets the condition in the querybuilder.
To force doctrine to "reload" the data from the database, you should refresh the blogPost entity:
$em->refresh($blogPost);
and also include refrech option on cascade operations of the relation definition:
#OneToMany(targetEntity="BlogTag", mappedBy="post", cascade={"refresh"})
References:
what cascade refresh means in doctrine 2
refresh objects: different question but same solution

Answer 2

Thanks #Jannes Botis for refresh. But in my case the code itself is wrong. There need a slight change in it.
BlogTags.php
/**
* #ORM\ManyToMany(targetEntity="BlogPost", mappedBy="blogTags")
*/
private $blogPosts;
BlogPost.php
/**
* #var Collection|BlogTags[]
*
* #ORM\ManyToMany(targetEntity="BlogTags", inversedBy="blogPosts", cascade={"refresh"})
* #ORM\JoinTable(
* name="fz__blog_n_tag",
* joinColumns={
* #ORM\JoinColumn(name="blog_id", referencedColumnName="id")
* },
* inverseJoinColumns={
* #ORM\JoinColumn(name="tag_id", referencedColumnName="id")
* }
* )
* #ORM\OrderBy({"name": "ASC"})
*/
private $blogTags;
This created the join_table. Allready I have a join_table. Although This code is for reference to someone.
Controller.php
// This is my old Code
$bp = $em->getRepository('App:BlogPost')->getAllActivePostsByTags($slug, "DESC", $page, self::PAGE_LIMIT);
// This is my New Code
$bp = $em->getRepository('App:BlogTags')->getAllActivePostsByTags($slug, "DESC", $page, self::PAGE_LIMIT);
Repository.php
public function getAllActivePostsByTags($value, $order = "DESC", $currentPage = 1, $limit = 10)
{
$query = $this->createQueryBuilder('t')
->select('t','p','tx')
->innerJoin('t.blogPosts', 'p')
->innerJoin('p.blogTags', 'tx')
->where('p.isActive = :val1')
->andWhere('t.slug = :val2')
->setParameter('val1', true)
->setParameter('val2', $value)
->orderBy('p.id', $order)
->getQuery();
$paginator = $this->paginate($query, $currentPage, $limit);
return $paginator;
}
I not changed my old twig file completely. As it throws error at many places. Because now i'm using tags repo instead of blog. So i modified the twig with
{% include 'frontend/page/blog_home.html.twig' with { 'bp':bp|first.blogPosts } %}
Help me on this (twig file): There is only one tag, that's why |first twig filter
Clarify me with this twig filter. Do I'm doing right. Give me suggestion to improve on it. I tried bp[0] This trows error.
Finally: By using old code in controller it returns 14 db hits. Now it returns only 8. Even there are more tags in a post (but old one returns more).