Symfony 2: INNER JOIN on non related table with doctrine query builder

Question

I'm trying to build a query with the doctrine query builder which joins a non related table like this:

$query = $this->createQueryBuilder('gpr')
        ->select('gpr, p')
        ->innerJoin('TPost', 'p')
        ->where('gpr.contentId = p.contentId')

But this doesn't work. I still get an error:

Error: Identification Variable TPost used in join path expression but was not defined before.

I searched for this error message and everybody answered to use the table alias + attribute like p.someAttribute. But the table I want to join isn't related in the table I start my select from.

As a normal mysql query i would write it like this:

SELECT * FROM t_group_publication_rel gpr 
INNER JOIN t_post p 
WHERE gpr.content_id = p.content_id

Any ideas what i'm doing wrong?

Magnetics

We can use DQL to perform a join with unrelated Objects? I do not know. If possible, it0s interesting =). – Hartzog

Why don't you just build a relation between these two, if you want to join them? – Hillie

In this case a relation wouldn't be enough. I would need relations to 3 different tables and any record could only set a reference to 1 of these 3. – Magnetics

Is it slower if I use the find methods in my controller instead of building a query? I would say yes because there are much more queries in the background right? – Magnetics

So I mean not only 1 find method. The combination of 2 different finds in a loop. – Magnetics

Answer 1

Today I was working on similar task and remembered that I opened this issue. I don't know since which doctrine version it's working but right now you can easily join the child classes in inheritance mapping. So a query like this is working without any problem:

$query = $this->createQueryBuilder('c')
        ->select('c')
        ->leftJoin('MyBundleName:ChildOne', 'co', 'WITH', 'co.id = c.id')
        ->leftJoin('MyBundleName:ChildTwo', 'ct', 'WITH', 'ct.id = c.id')
        ->orderBy('c.createdAt', 'DESC')
        ->where('co.group = :group OR ct.group = :group')
        ->setParameter('group', $group)
        ->setMaxResults(20);

I start the query in my parent class which is using inheritance mapping. In my previous post it was a different starting point but the same issue if I remember right.

Because it was a big problem when I started this issue I think it could be also interesting for other people which don't know about it.

Magnetics

Thank you ! This really helped, I've been searching for hours. – Humbuggery

if i dont have MyBundleName:ChildTwo repository, i want to write query with table name then what is the solution.? – Resolvable

@MohammadFareed The reference to the entity is not a repository, it's either a string in '<bundleName>:<endityClassName>' form OR the FQCN of the entity class, e.g. \AppBundle\Entity\ChildTwo::class – Ottie

What's the difference between using WITH or ON? – Polymerize

Answer 2

Joins between entities without associations were not possible until version 2.4, where you can generate an arbitrary join with the following syntax:

$query = $em->createQuery('SELECT u FROM User u JOIN Blacklist b WITH u.email = b.email');

Reference: http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/dql-doctrine-query-language.html

A

This is awesome! Note that the WITH clause is required in this case, otherwise it results in a syntax error. However you can just use a dummy condition and essentially obtain a real cross join, which DQL doesn't otherwise support. For example: SELECT u FROM User u JOIN Items i WITH 0 = 0. This can be useful for complex statistics. – Koval

Answer 3

$dql = "SELECT 
    a, md.fisrtName , md.LastName, mj
    FROM MembersBundle:Memberdata md
        INNER JOIN MembersBundle:Address a WITH md = a.empID
        INNER JOIN MembersBundle:Memberjob mj WITH md = mj.memberData
            ...
    WHERE
        a.dateOfChange IS NULL
    AND WHERE
        md.someField = 'SomeValue'";

return $em->createQuery( $dql )->getResult();

Malformation

While this answer doesn't provide required details, there's nothing to cite as Doctrine's documentation completely lacks coverage of these types of joins. This worked for me. I know enough sql to parse what was intended and not enough doctrine to connect the dots. – Benthamism

Answer 4

A DQL join only works if an association is defined in your mapping. In your case, I'd say it's much easier to do a native query and use ResultSetMapping to populate your objects.

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