16. The QueryBuilder

A QueryBuilder provides an API that is designed for conditionally constructing a DQL query in several steps.

It provides a set of classes and methods that is able to programmatically build queries, and also provides a fluent API. This means that you can change between one methodology to the other as you want, and also pick one if you prefer.

16.1. Constructing a new QueryBuilder object

The same way you build a normal Query, you build a QueryBuilder object, just providing the correct method name. Here is an example how to build a QueryBuilder object:

<?php
// $em instanceof EntityManager

// example1: creating a QueryBuilder instance
$qb = $em->createQueryBuilder();

Once you have created an instance of QueryBuilder, it provides a set of useful informative functions that you can use. One good example is to inspect what type of object the QueryBuilder is.

<?php
// $qb instanceof QueryBuilder

// example2: retrieving type of QueryBuilder
echo $qb->getType(); // Prints: 0

There’re currently 3 possible return values for getType():

  • QueryBuilder::SELECT, which returns value 0
  • QueryBuilder::DELETE, returning value 1
  • QueryBuilder::UPDATE, which returns value 2

It is possible to retrieve the associated EntityManager of the current QueryBuilder, its DQL and also a Query object when you finish building your DQL.

<?php
// $qb instanceof QueryBuilder

// example3: retrieve the associated EntityManager
$em = $qb->getEntityManager();

// example4: retrieve the DQL string of what was defined in QueryBuilder
$dql = $qb->getDql();

// example5: retrieve the associated Query object with the processed DQL
$q = $qb->getQuery();

Internally, QueryBuilder works with a DQL cache to increase performance. Any changes that may affect the generated DQL actually modifies the state of QueryBuilder to a stage we call STATE_DIRTY. One QueryBuilder can be in two different states:

  • QueryBuilder::STATE_CLEAN, which means DQL haven’t been altered since last retrieval or nothing were added since its instantiation
  • QueryBuilder::STATE_DIRTY, means DQL query must (and will) be processed on next retrieval

16.2. Working with QueryBuilder

16.2.1. High level API methods

To simplify even more the way you build a query in Doctrine, we can take advantage of what we call Helper methods. For all base code, there is a set of useful methods to simplify a programmer’s life. To illustrate how to work with them, here is the same example 6 re-written using QueryBuilder helper methods:

<?php
// $qb instanceof QueryBuilder

$qb->select('u')
   ->from('User', 'u')
   ->where('u.id = ?1')
   ->orderBy('u.name', 'ASC');

QueryBuilder helper methods are considered the standard way to build DQL queries. Although it is supported, it should be avoided to use string based queries and greatly encouraged to use $qb->expr()->* methods. Here is a converted example 8 to suggested standard way to build queries:

<?php
// $qb instanceof QueryBuilder

$qb->select(array('u')) // string 'u' is converted to array internally
   ->from('User', 'u')
   ->where($qb->expr()->orX(
       $qb->expr()->eq('u.id', '?1'),
       $qb->expr()->like('u.nickname', '?2')
   ))
   ->orderBy('u.surname', 'ASC'));

Here is a complete list of helper methods available in QueryBuilder:

<?php
class QueryBuilder
{
    // Example - $qb->select('u')
    // Example - $qb->select(array('u', 'p'))
    // Example - $qb->select($qb->expr()->select('u', 'p'))
    public function select($select = null);

    // Example - $qb->delete('User', 'u')
    public function delete($delete = null, $alias = null);

    // Example - $qb->update('Group', 'g')
    public function update($update = null, $alias = null);

    // Example - $qb->set('u.firstName', $qb->expr()->literal('Arnold'))
    // Example - $qb->set('u.numChilds', 'u.numChilds + ?1')
    // Example - $qb->set('u.numChilds', $qb->expr()->sum('u.numChilds', '?1'))
    public function set($key, $value);

    // Example - $qb->from('Phonenumber', 'p')
    public function from($from, $alias = null);

    // Example - $qb->innerJoin('u.Group', 'g', Expr\Join::WITH, $qb->expr()->eq('u.status_id', '?1'))
    // Example - $qb->innerJoin('u.Group', 'g', 'WITH', 'u.status = ?1')
    public function innerJoin($join, $alias = null, $conditionType = null, $condition = null);

    // Example - $qb->leftJoin('u.Phonenumbers', 'p', Expr\Join::WITH, $qb->expr()->eq('p.area_code', 55))
    // Example - $qb->leftJoin('u.Phonenumbers', 'p', 'WITH', 'p.area_code = 55')
    public function leftJoin($join, $alias = null, $conditionType = null, $condition = null);

    // NOTE: ->where() overrides all previously set conditions
    //
    // Example - $qb->where('u.firstName = ?1', $qb->expr()->eq('u.surname', '?2'))
    // Example - $qb->where($qb->expr()->andX($qb->expr()->eq('u.firstName', '?1'), $qb->expr()->eq('u.surname', '?2')))
    // Example - $qb->where('u.firstName = ?1 AND u.surname = ?2')
    public function where($where);

    // Example - $qb->andWhere($qb->expr()->orX($qb->expr()->lte('u.age', 40), 'u.numChild = 0'))
    public function andWhere($where);

    // Example - $qb->orWhere($qb->expr()->between('u.id', 1, 10));
    public function orWhere($where);

    // NOTE: -> groupBy() overrides all previously set grouping conditions
    //
    // Example - $qb->groupBy('u.id')
    public function groupBy($groupBy);

    // Example - $qb->addGroupBy('g.name')
    public function addGroupBy($groupBy);

    // NOTE: -> having() overrides all previously set having conditions
    //
    // Example - $qb->having('u.salary >= ?1')
    // Example - $qb->having($qb->expr()->gte('u.salary', '?1'))
    public function having($having);

    // Example - $qb->andHaving($qb->expr()->gt($qb->expr()->count('u.numChild'), 0))
    public function andHaving($having);

    // Example - $qb->orHaving($qb->expr()->lte('g.managerLevel', '100'))
    public function orHaving($having);

    // NOTE: -> orderBy() overrides all previously set ordering conditions
    //
    // Example - $qb->orderBy('u.surname', 'DESC')
    public function orderBy($sort, $order = null);

    // Example - $qb->addOrderBy('u.firstName')
    public function addOrderBy($sort, $order = null); // Default $order = 'ASC'
}

16.2.2. Binding parameters to your query

Doctrine supports dynamic binding of parameters to your query, similar to preparing queries. You can use both strings and numbers as placeholders, although both have a slightly different syntax. Additionally, you must make your choice: Mixing both styles is not allowed. Binding parameters can simply be achieved as follows:

<?php
// $qb instanceof QueryBuilder

$qb->select('u')
   ->from('User u')
   ->where('u.id = ?1')
   ->orderBy('u.name', 'ASC')
   ->setParameter(1, 100); // Sets ?1 to 100, and thus we will fetch a user with u.id = 100

You are not forced to enumerate your placeholders as the alternative syntax is available:

<?php
// $qb instanceof QueryBuilder

$qb->select('u')
   ->from('User u')
   ->where('u.id = :identifier')
   ->orderBy('u.name', 'ASC')
   ->setParameter('identifier', 100); // Sets :identifier to 100, and thus we will fetch a user with u.id = 100

Note that numeric placeholders start with a ? followed by a number while the named placeholders start with a : followed by a string.

Calling setParameter() automatically infers which type you are setting as value. This works for integers, arrays of strings/integers, DateTime instances and for managed entities. If you want to set a type explicitly you can call the third argument to setParameter() explicitly. It accepts either a PDO type or a DBAL Type name for conversion.

If you’ve got several parameters to bind to your query, you can also use setParameters() instead of setParameter() with the following syntax:

<?php
// $qb instanceof QueryBuilder

// Query here...
$qb->setParameters(array(1 => 'value for ?1', 2 => 'value for ?2'));

Getting already bound parameters is easy - simply use the above mentioned syntax with “getParameter()” or “getParameters()”:

<?php
// $qb instanceof QueryBuilder

// See example above
$params = $qb->getParameters();
// $params instanceof \Doctrine\Common\Collections\ArrayCollection

// Equivalent to
$param = $qb->getParameter(1);
// $param instanceof \Doctrine\ORM\Query\Parameter

Note: If you try to get a parameter that was not bound yet, getParameter() simply returns NULL.

The API of a Query Parameter is:

namespace Doctrine\ORM\Query;

class Parameter
{
    public function getName();
    public function getValue();
    public function getType();
    public function setValue($value, $type = null);
}

16.2.3. Limiting the Result

To limit a result the query builder has some methods in common with the Query object which can be retrieved from EntityManager#createQuery().

<?php
// $qb instanceof QueryBuilder
$offset = (int)$_GET['offset'];
$limit = (int)$_GET['limit'];

$qb->add('select', 'u')
   ->add('from', 'User u')
   ->add('orderBy', 'u.name ASC')
   ->setFirstResult( $offset )
   ->setMaxResults( $limit );

16.2.4. Executing a Query

The QueryBuilder is a builder object only, it has no means of actually executing the Query. Additionally a set of parameters such as query hints cannot be set on the QueryBuilder itself. This is why you always have to convert a querybuilder instance into a Query object:

<?php
// $qb instanceof QueryBuilder
$query = $qb->getQuery();

// Set additional Query options
$query->setQueryHint('foo', 'bar');
$query->useResultCache('my_cache_id');

// Execute Query
$result = $query->getResult();
$single = $query->getSingleResult();
$array = $query->getArrayResult();
$scalar = $query->getScalarResult();
$singleScalar = $query->getSingleScalarResult();

16.2.5. The Expr class

To workaround some of the issues that add() method may cause, Doctrine created a class that can be considered as a helper for building expressions. This class is called Expr, which provides a set of useful methods to help build expressions:

<?php
// $qb instanceof QueryBuilder

// example8: QueryBuilder port of:
// "SELECT u FROM User u WHERE u.id = ? OR u.nickname LIKE ? ORDER BY u.name ASC" using Expr class
$qb->add('select', new Expr\Select(array('u')))
   ->add('from', new Expr\From('User', 'u'))
   ->add('where', $qb->expr()->orX(
       $qb->expr()->eq('u.id', '?1'),
       $qb->expr()->like('u.nickname', '?2')
   ))
   ->add('orderBy', new Expr\OrderBy('u.name', 'ASC'));

Although it still sounds complex, the ability to programmatically create conditions are the main feature of Expr. Here it is a complete list of supported helper methods available:

<?php
class Expr
{
    /** Conditional objects **/

    // Example - $qb->expr()->andX($cond1 [, $condN])->add(...)->...
    public function andX($x = null); // Returns Expr\AndX instance

    // Example - $qb->expr()->orX($cond1 [, $condN])->add(...)->...
    public function orX($x = null); // Returns Expr\OrX instance


    /** Comparison objects **/

    // Example - $qb->expr()->eq('u.id', '?1') => u.id = ?1
    public function eq($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->neq('u.id', '?1') => u.id <> ?1
    public function neq($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->lt('u.id', '?1') => u.id < ?1
    public function lt($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->lte('u.id', '?1') => u.id <= ?1
    public function lte($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->gt('u.id', '?1') => u.id > ?1
    public function gt($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->gte('u.id', '?1') => u.id >= ?1
    public function gte($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->isNull('u.id') => u.id IS NULL
    public function isNull($x); // Returns string

    // Example - $qb->expr()->isNotNull('u.id') => u.id IS NOT NULL
    public function isNotNull($x); // Returns string


    /** Arithmetic objects **/

    // Example - $qb->expr()->prod('u.id', '2') => u.id * 2
    public function prod($x, $y); // Returns Expr\Math instance

    // Example - $qb->expr()->diff('u.id', '2') => u.id - 2
    public function diff($x, $y); // Returns Expr\Math instance

    // Example - $qb->expr()->sum('u.id', '2') => u.id + 2
    public function sum($x, $y); // Returns Expr\Math instance

    // Example - $qb->expr()->quot('u.id', '2') => u.id / 2
    public function quot($x, $y); // Returns Expr\Math instance


    /** Pseudo-function objects **/

    // Example - $qb->expr()->exists($qb2->getDql())
    public function exists($subquery); // Returns Expr\Func instance

    // Example - $qb->expr()->all($qb2->getDql())
    public function all($subquery); // Returns Expr\Func instance

    // Example - $qb->expr()->some($qb2->getDql())
    public function some($subquery); // Returns Expr\Func instance

    // Example - $qb->expr()->any($qb2->getDql())
    public function any($subquery); // Returns Expr\Func instance

    // Example - $qb->expr()->not($qb->expr()->eq('u.id', '?1'))
    public function not($restriction); // Returns Expr\Func instance

    // Example - $qb->expr()->in('u.id', array(1, 2, 3))
    // Make sure that you do NOT use something similar to $qb->expr()->in('value', array('stringvalue')) as this will cause Doctrine to throw an Exception.
    // Instead, use $qb->expr()->in('value', array('?1')) and bind your parameter to ?1 (see section above)
    public function in($x, $y); // Returns Expr\Func instance

    // Example - $qb->expr()->notIn('u.id', '2')
    public function notIn($x, $y); // Returns Expr\Func instance

    // Example - $qb->expr()->like('u.firstname', $qb->expr()->literal('Gui%'))
    public function like($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->notLike('u.firstname', $qb->expr()->literal('Gui%'))
    public function notLike($x, $y); // Returns Expr\Comparison instance

    // Example - $qb->expr()->between('u.id', '1', '10')
    public function between($val, $x, $y); // Returns Expr\Func


    /** Function objects **/

    // Example - $qb->expr()->trim('u.firstname')
    public function trim($x); // Returns Expr\Func

    // Example - $qb->expr()->concat('u.firstname', $qb->expr()->concat($qb->expr()->literal(' '), 'u.lastname'))
    public function concat($x, $y); // Returns Expr\Func

    // Example - $qb->expr()->substring('u.firstname', 0, 1)
    public function substring($x, $from, $len); // Returns Expr\Func

    // Example - $qb->expr()->lower('u.firstname')
    public function lower($x); // Returns Expr\Func

    // Example - $qb->expr()->upper('u.firstname')
    public function upper($x); // Returns Expr\Func

    // Example - $qb->expr()->length('u.firstname')
    public function length($x); // Returns Expr\Func

    // Example - $qb->expr()->avg('u.age')
    public function avg($x); // Returns Expr\Func

    // Example - $qb->expr()->max('u.age')
    public function max($x); // Returns Expr\Func

    // Example - $qb->expr()->min('u.age')
    public function min($x); // Returns Expr\Func

    // Example - $qb->expr()->abs('u.currentBalance')
    public function abs($x); // Returns Expr\Func

    // Example - $qb->expr()->sqrt('u.currentBalance')
    public function sqrt($x); // Returns Expr\Func

    // Example - $qb->expr()->count('u.firstname')
    public function count($x); // Returns Expr\Func

    // Example - $qb->expr()->countDistinct('u.surname')
    public function countDistinct($x); // Returns Expr\Func
}

16.2.6. Low Level API

Now we have describe the low level (thought of as the hardcore method) of creating queries. It may be useful to work at this level for optimization purposes, but most of the time it is preferred to work at a higher level of abstraction.

All helper methods in QueryBuilder actually rely on a single one: add(). This method is responsible of building every piece of DQL. It takes 3 parameters: $dqlPartName, $dqlPart and $append (default=false)

  • $dqlPartName: Where the $dqlPart should be placed. Possible values: select, from, where, groupBy, having, orderBy
  • $dqlPart: What should be placed in $dqlPartName. Accepts a string or any instance of Doctrine\ORM\Query\Expr\*
  • $append: Optional flag (default=false) if the $dqlPart should override all previously defined items in $dqlPartName or not (no effect on the where and having DQL query parts, which always override all previously defined items)
<?php
// $qb instanceof QueryBuilder

// example6: how to define:
// "SELECT u FROM User u WHERE u.id = ? ORDER BY u.name ASC"
// using QueryBuilder string support
$qb->add('select', 'u')
   ->add('from', 'User u')
   ->add('where', 'u.id = ?1')
   ->add('orderBy', 'u.name ASC');

16.2.7. Expr* classes

When you call add() with string, it internally evaluates to an instance of Doctrine\ORM\Query\Expr\Expr\* class. Here is the same query of example 6 written using Doctrine\ORM\Query\Expr\Expr\* classes:

<?php
// $qb instanceof QueryBuilder

// example7: how to define:
// "SELECT u FROM User u WHERE u.id = ? ORDER BY u.name ASC"
// using QueryBuilder using Expr\* instances
$qb->add('select', new Expr\Select(array('u')))
   ->add('from', new Expr\From('User', 'u'))
   ->add('where', new Expr\Comparison('u.id', '=', '?1'))
   ->add('orderBy', new Expr\OrderBy('u.name', 'ASC'));

Of course this is the hardest way to build a DQL query in Doctrine. To simplify some of these efforts, we introduce what we call as Expr helper class.

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