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doctrine2/lib/Doctrine/ORM/Tools/Pagination/LimitSubqueryOutputWalker.php

563 lines
20 KiB
PHP

<?php
/**
* Doctrine ORM
*
* LICENSE
*
* This source file is subject to the new BSD license that is bundled
* with this package in the file LICENSE.txt.
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to kontakt@beberlei.de so I can send you a copy immediately.
*/
namespace Doctrine\ORM\Tools\Pagination;
use Doctrine\DBAL\Platforms\DB2Platform;
use Doctrine\DBAL\Platforms\OraclePlatform;
use Doctrine\DBAL\Platforms\PostgreSqlPlatform;
use Doctrine\DBAL\Platforms\SQLAnywherePlatform;
use Doctrine\DBAL\Platforms\SQLServerPlatform;
use Doctrine\ORM\Query\AST\ArithmeticExpression;
use Doctrine\ORM\Query\AST\ArithmeticFactor;
use Doctrine\ORM\Query\AST\ArithmeticTerm;
use Doctrine\ORM\Query\AST\Literal;
use Doctrine\ORM\Query\AST\OrderByClause;
use Doctrine\ORM\Query\AST\OrderByItem;
use Doctrine\ORM\Query\AST\PartialObjectExpression;
use Doctrine\ORM\Query\AST\PathExpression;
use Doctrine\ORM\Query\AST\SelectExpression;
use Doctrine\ORM\Query\AST\SimpleArithmeticExpression;
use Doctrine\ORM\Query\Expr\OrderBy;
use Doctrine\ORM\Query\Expr\Select;
use Doctrine\ORM\Query\SqlWalker;
use Doctrine\ORM\Query\AST\SelectStatement;
/**
* Wraps the query in order to select root entity IDs for pagination.
*
* Given a DQL like `SELECT u FROM User u` it will generate an SQL query like:
* SELECT DISTINCT <id> FROM (<original SQL>) LIMIT x OFFSET y
*
* Works with composite keys but cannot deal with queries that have multiple
* root entities (e.g. `SELECT f, b from Foo, Bar`)
*
* @author Sander Marechal <s.marechal@jejik.com>
*/
class LimitSubqueryOutputWalker extends SqlWalker
{
/**
* @var \Doctrine\DBAL\Platforms\AbstractPlatform
*/
private $_platform;
/**
* @var \Doctrine\ORM\Query\ResultSetMapping
*/
private $_rsm;
/**
* @var array
*/
private $_queryComponents;
/**
* @var int
*/
private $firstResult;
/**
* @var int
*/
private $maxResults;
/**
* @var \Doctrine\ORM\EntityManager
*/
private $_em;
/**
* The quote strategy.
*
* @var \Doctrine\ORM\Mapping\QuoteStrategy
*/
private $_quoteStrategy;
/**
* @var array
*/
private $orderByPathExpressions = [];
/** @var bool $inSubselect */
private $inSubselect = false;
/**
* Constructor.
*
* Stores various parameters that are otherwise unavailable
* because Doctrine\ORM\Query\SqlWalker keeps everything private without
* accessors.
*
* @param \Doctrine\ORM\Query $query
* @param \Doctrine\ORM\Query\ParserResult $parserResult
* @param array $queryComponents
*/
public function __construct($query, $parserResult, array $queryComponents)
{
$this->_platform = $query->getEntityManager()->getConnection()->getDatabasePlatform();
$this->_rsm = $parserResult->getResultSetMapping();
$this->_queryComponents = $queryComponents;
// Reset limit and offset
$this->firstResult = $query->getFirstResult();
$this->maxResults = $query->getMaxResults();
$query->setFirstResult(null)->setMaxResults(null);
$this->_em = $query->getEntityManager();
$this->_quoteStrategy = $this->_em->getConfiguration()->getQuoteStrategy();
parent::__construct($query, $parserResult, $queryComponents);
}
/**
* Check if the platform supports the ROW_NUMBER window function.
*
* @return bool
*/
private function platformSupportsRowNumber()
{
return $this->_platform instanceof PostgreSqlPlatform
|| $this->_platform instanceof SQLServerPlatform
|| $this->_platform instanceof OraclePlatform
|| $this->_platform instanceof SQLAnywherePlatform
|| $this->_platform instanceof DB2Platform
|| (method_exists($this->_platform, "supportsRowNumberFunction")
&& $this->_platform->supportsRowNumberFunction());
}
/**
* Rebuilds a select statement's order by clause for use in a
* ROW_NUMBER() OVER() expression.
*
* @param SelectStatement $AST
*/
private function rebuildOrderByForRowNumber(SelectStatement $AST)
{
$orderByClause = $AST->orderByClause;
$selectAliasToExpressionMap = [];
// Get any aliases that are available for select expressions.
foreach ($AST->selectClause->selectExpressions as $selectExpression) {
$selectAliasToExpressionMap[$selectExpression->fieldIdentificationVariable] = $selectExpression->expression;
}
// Rebuild string orderby expressions to use the select expression they're referencing
foreach ($orderByClause->orderByItems as $orderByItem) {
if (is_string($orderByItem->expression) && isset($selectAliasToExpressionMap[$orderByItem->expression])) {
$orderByItem->expression = $selectAliasToExpressionMap[$orderByItem->expression];
}
}
$func = new RowNumberOverFunction("dctrn_rownum");
$func->orderByClause = $AST->orderByClause;
$AST->selectClause->selectExpressions[] = new SelectExpression($func, "dctrn_rownum", true);
// No need for an order by clause, we'll order by rownum in the outer query.
$AST->orderByClause = null;
}
/**
* Walks down a SelectStatement AST node, wrapping it in a SELECT DISTINCT.
*
* @param SelectStatement $AST
*
* @return string
*
* @throws \RuntimeException
*/
public function walkSelectStatement(SelectStatement $AST)
{
if ($this->platformSupportsRowNumber()) {
return $this->walkSelectStatementWithRowNumber($AST);
}
return $this->walkSelectStatementWithoutRowNumber($AST);
}
/**
* Walks down a SelectStatement AST node, wrapping it in a SELECT DISTINCT.
* This method is for use with platforms which support ROW_NUMBER.
*
* @param SelectStatement $AST
*
* @return string
*
* @throws \RuntimeException
*/
public function walkSelectStatementWithRowNumber(SelectStatement $AST)
{
$hasOrderBy = false;
$outerOrderBy = " ORDER BY dctrn_minrownum ASC";
$orderGroupBy = '';
if ($AST->orderByClause instanceof OrderByClause) {
$hasOrderBy = true;
$this->rebuildOrderByForRowNumber($AST);
}
$innerSql = $this->getInnerSQL($AST);
$sqlIdentifier = $this->getSQLIdentifier($AST);
if ($hasOrderBy) {
$orderGroupBy = " GROUP BY " . implode(', ', $sqlIdentifier);
$sqlIdentifier[] = "MIN(" . $this->walkResultVariable("dctrn_rownum") . ") AS dctrn_minrownum";
}
// Build the counter query
$sql = sprintf(
'SELECT DISTINCT %s FROM (%s) dctrn_result',
implode(', ', $sqlIdentifier),
$innerSql
);
if ($hasOrderBy) {
$sql .= $orderGroupBy . $outerOrderBy;
}
// Apply the limit and offset.
$sql = $this->_platform->modifyLimitQuery(
$sql,
$this->maxResults,
$this->firstResult
);
// Add the columns to the ResultSetMapping. It's not really nice but
// it works. Preferably I'd clear the RSM or simply create a new one
// but that is not possible from inside the output walker, so we dirty
// up the one we have.
foreach ($sqlIdentifier as $property => $alias) {
$this->_rsm->addScalarResult($alias, $property);
}
return $sql;
}
/**
* Walks down a SelectStatement AST node, wrapping it in a SELECT DISTINCT.
* This method is for platforms which DO NOT support ROW_NUMBER.
*
* @param SelectStatement $AST
* @param bool $addMissingItemsFromOrderByToSelect
*
* @return string
*
* @throws \RuntimeException
*/
public function walkSelectStatementWithoutRowNumber(SelectStatement $AST, $addMissingItemsFromOrderByToSelect = true)
{
// We don't want to call this recursively!
if ($AST->orderByClause instanceof OrderByClause && $addMissingItemsFromOrderByToSelect) {
// In the case of ordering a query by columns from joined tables, we
// must add those columns to the select clause of the query BEFORE
// the SQL is generated.
$this->addMissingItemsFromOrderByToSelect($AST);
}
// Remove order by clause from the inner query
// It will be re-appended in the outer select generated by this method
$orderByClause = $AST->orderByClause;
$AST->orderByClause = null;
$innerSql = $this->getInnerSQL($AST);
$sqlIdentifier = $this->getSQLIdentifier($AST);
// Build the counter query
$sql = sprintf('SELECT DISTINCT %s FROM (%s) dctrn_result',
implode(', ', $sqlIdentifier), $innerSql);
// http://www.doctrine-project.org/jira/browse/DDC-1958
$sql = $this->preserveSqlOrdering($sqlIdentifier, $innerSql, $sql, $orderByClause);
// Apply the limit and offset.
$sql = $this->_platform->modifyLimitQuery(
$sql, $this->maxResults, $this->firstResult
);
// Add the columns to the ResultSetMapping. It's not really nice but
// it works. Preferably I'd clear the RSM or simply create a new one
// but that is not possible from inside the output walker, so we dirty
// up the one we have.
foreach ($sqlIdentifier as $property => $alias) {
$this->_rsm->addScalarResult($alias, $property);
}
// Restore orderByClause
$AST->orderByClause = $orderByClause;
return $sql;
}
/**
* Finds all PathExpressions in an AST's OrderByClause, and ensures that
* the referenced fields are present in the SelectClause of the passed AST.
*
* @param SelectStatement $AST
*/
private function addMissingItemsFromOrderByToSelect(SelectStatement $AST)
{
$this->orderByPathExpressions = [];
// We need to do this in another walker because otherwise we'll end up
// polluting the state of this one.
$walker = clone $this;
// This will populate $orderByPathExpressions via
// LimitSubqueryOutputWalker::walkPathExpression, which will be called
// as the select statement is walked. We'll end up with an array of all
// path expressions referenced in the query.
$walker->walkSelectStatementWithoutRowNumber($AST, false);
$orderByPathExpressions = $walker->getOrderByPathExpressions();
// Get a map of referenced identifiers to field names.
$selects = [];
foreach ($orderByPathExpressions as $pathExpression) {
$idVar = $pathExpression->identificationVariable;
$field = $pathExpression->field;
if (!isset($selects[$idVar])) {
$selects[$idVar] = [];
}
$selects[$idVar][$field] = true;
}
// Loop the select clause of the AST and exclude items from $select
// that are already being selected in the query.
foreach ($AST->selectClause->selectExpressions as $selectExpression) {
if ($selectExpression instanceof SelectExpression) {
$idVar = $selectExpression->expression;
if (!is_string($idVar)) {
continue;
}
$field = $selectExpression->fieldIdentificationVariable;
if ($field === null) {
// No need to add this select, as we're already fetching the whole object.
unset($selects[$idVar]);
} else {
unset($selects[$idVar][$field]);
}
}
}
// Add select items which were not excluded to the AST's select clause.
foreach ($selects as $idVar => $fields) {
$AST->selectClause->selectExpressions[] = new SelectExpression(new PartialObjectExpression($idVar, array_keys($fields)), null, true);
}
}
/**
* Generates new SQL for statements with an order by clause
*
* @param array $sqlIdentifier
* @param string $innerSql
* @param string $sql
* @param OrderByClause $orderByClause
*
* @return string
*/
private function preserveSqlOrdering(array $sqlIdentifier, $innerSql, $sql, $orderByClause)
{
// If the sql statement has an order by clause, we need to wrap it in a new select distinct
// statement
if (! $orderByClause instanceof OrderByClause) {
return $sql;
}
// Rebuild the order by clause to work in the scope of the new select statement
/* @var array $orderBy an array of rebuilt order by items */
$orderBy = $this->rebuildOrderByClauseForOuterScope($orderByClause);
// Build the select distinct statement
$sql = sprintf(
'SELECT DISTINCT %s FROM (%s) dctrn_result ORDER BY %s',
implode(', ', $sqlIdentifier),
$innerSql,
implode(', ', $orderBy)
);
return $sql;
}
/**
* Generates a new order by clause that works in the scope of a select query wrapping the original
*
* @param OrderByClause $orderByClause
* @return array
*/
private function rebuildOrderByClauseForOuterScope(OrderByClause $orderByClause)
{
$dqlAliasToSqlTableAliasMap
= $searchPatterns
= $replacements
= $dqlAliasToClassMap
= $selectListAdditions
= $orderByItems
= [];
// Generate DQL alias -> SQL table alias mapping
foreach(array_keys($this->_rsm->aliasMap) as $dqlAlias) {
$dqlAliasToClassMap[$dqlAlias] = $class = $this->_queryComponents[$dqlAlias]['metadata'];
$dqlAliasToSqlTableAliasMap[$dqlAlias] = $this->getSQLTableAlias($class->getTableName(), $dqlAlias);
}
// Pattern to find table path expressions in the order by clause
$fieldSearchPattern = '/(?<![a-z0-9_])%s\.%s(?![a-z0-9_])/i';
// Generate search patterns for each field's path expression in the order by clause
foreach($this->_rsm->fieldMappings as $fieldAlias => $columnName) {
$dqlAliasForFieldAlias = $this->_rsm->columnOwnerMap[$fieldAlias];
$columnName = $this->_quoteStrategy->getColumnName(
$columnName,
$dqlAliasToClassMap[$dqlAliasForFieldAlias],
$this->_em->getConnection()->getDatabasePlatform()
);
$sqlTableAliasForFieldAlias = $dqlAliasToSqlTableAliasMap[$dqlAliasForFieldAlias];
$searchPatterns[] = sprintf($fieldSearchPattern, $sqlTableAliasForFieldAlias, $columnName);
$replacements[] = $fieldAlias;
}
foreach($orderByClause->orderByItems as $orderByItem) {
// Walk order by item to get string representation of it
$orderByItemString = $this->walkOrderByItem($orderByItem);
// Replace path expressions in the order by clause with their column alias
$orderByItemString = preg_replace($searchPatterns, $replacements, $orderByItemString);
$orderByItems[] = $orderByItemString;
}
return $orderByItems;
}
/**
* getter for $orderByPathExpressions
*
* @return array
*/
public function getOrderByPathExpressions()
{
return $this->orderByPathExpressions;
}
/**
* @param $AST
* @return string
* @throws \Doctrine\ORM\OptimisticLockException
* @throws \Doctrine\ORM\Query\QueryException
*/
private function getInnerSQL($AST)
{
// Set every select expression as visible(hidden = false) to
// make $AST have scalar mappings properly - this is relevant for referencing selected
// fields from outside the subquery, for example in the ORDER BY segment
$hiddens = array();
foreach ($AST->selectClause->selectExpressions as $idx => $expr) {
$hiddens[$idx] = $expr->hiddenAliasResultVariable;
$expr->hiddenAliasResultVariable = false;
}
$innerSql = parent::walkSelectStatement($AST);
// Restore hiddens
foreach ($AST->selectClause->selectExpressions as $idx => $expr) {
$expr->hiddenAliasResultVariable = $hiddens[$idx];
}
return $innerSql;
}
/**
* @param $AST
* @return array
*/
private function getSQLIdentifier($AST)
{
// Find out the SQL alias of the identifier column of the root entity.
// It may be possible to make this work with multiple root entities but that
// would probably require issuing multiple queries or doing a UNION SELECT.
// So for now, it's not supported.
// Get the root entity and alias from the AST fromClause.
$from = $AST->fromClause->identificationVariableDeclarations;
if (count($from) !== 1) {
throw new \RuntimeException("Cannot count query which selects two FROM components, cannot make distinction");
}
$fromRoot = reset($from);
$rootAlias = $fromRoot->rangeVariableDeclaration->aliasIdentificationVariable;
$rootClass = $this->_queryComponents[$rootAlias]['metadata'];
$rootIdentifier = $rootClass->identifier;
// For every identifier, find out the SQL alias by combing through the ResultSetMapping
$sqlIdentifier = array();
foreach ($rootIdentifier as $property) {
if (isset($rootClass->fieldMappings[$property])) {
foreach (array_keys($this->_rsm->fieldMappings, $property) as $alias) {
if ($this->_rsm->columnOwnerMap[$alias] == $rootAlias) {
$sqlIdentifier[$property] = $alias;
}
}
}
if (isset($rootClass->associationMappings[$property])) {
$joinColumn = $rootClass->associationMappings[$property]['joinColumns'][0]['name'];
foreach (array_keys($this->_rsm->metaMappings, $joinColumn) as $alias) {
if ($this->_rsm->columnOwnerMap[$alias] == $rootAlias) {
$sqlIdentifier[$property] = $alias;
}
}
}
}
if (count($sqlIdentifier) === 0) {
throw new \RuntimeException('The Paginator does not support Queries which only yield ScalarResults.');
}
if (count($rootIdentifier) != count($sqlIdentifier)) {
throw new \RuntimeException(sprintf(
'Not all identifier properties can be found in the ResultSetMapping: %s',
implode(', ', array_diff($rootIdentifier, array_keys($sqlIdentifier)))
));
}
return $sqlIdentifier;
}
/**
* {@inheritdoc}
*/
public function walkPathExpression($pathExpr)
{
if (!$this->inSubselect && !$this->platformSupportsRowNumber() && !in_array($pathExpr, $this->orderByPathExpressions)) {
$this->orderByPathExpressions[] = $pathExpr;
}
return parent::walkPathExpression($pathExpr);
}
/**
* {@inheritdoc}
*/
public function walkSubSelect($subselect)
{
// We don't want to add path expressions from subselects into the select clause of the containing query.
$this->inSubselect = true;
$sql = parent::walkSubselect($subselect);
$this->inSubselect = false;
return $sql;
}
}