From 5326ce6bca17efe66a144d8afba56af3a66053fd Mon Sep 17 00:00:00 2001
From: Johannes Meyer <johannes.meyer@netways.de>
Date: Thu, 28 May 2015 13:44:51 +0200
Subject: [PATCH] DbRepository: Add support for table specific aliases

This was previously only possible for the base table and in case one wanted
to use table aliases in the query column definition for non-base tables as
well, it did not work well due to not being explicitly supported. Now, to use
such table aliases one must initialize DbRepository::tableAliases.

refs #8826
---
 library/Icinga/Repository/DbRepository.php | 136 +++++++++++++++------
 library/Icinga/Repository/Repository.php   |   4 +-
 2 files changed, 102 insertions(+), 38 deletions(-)

diff --git a/library/Icinga/Repository/DbRepository.php b/library/Icinga/Repository/DbRepository.php
index 433842a57..f3b0c679c 100644
--- a/library/Icinga/Repository/DbRepository.php
+++ b/library/Icinga/Repository/DbRepository.php
@@ -17,6 +17,7 @@ use Icinga\Exception\StatementException;
  *
  * Additionally provided features:
  * <ul>
+ *  <li>Support for table aliases</li>
  *  <li>Automatic table prefix handling</li>
  *  <li>Insert, update and delete capabilities</li>
  *  <li>Differentiation between statement and query columns</li>
@@ -31,6 +32,17 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
      */
     protected $ds;
 
+    /**
+     * The table aliases being applied
+     *
+     * This must be initialized by repositories which are going to make use of table aliases. Every table for which
+     * aliased columns are provided must be defined in this array using its name as key and the alias being used as
+     * value. Failure to do so will result in invalid queries.
+     *
+     * @var array
+     */
+    protected $tableAliases;
+
     /**
      * The statement columns being provided
      *
@@ -111,6 +123,32 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
         return $this->queryColumns;
     }
 
+    /**
+     * Return the table aliases to be applied
+     *
+     * Calls $this->initializeTableAliases() in case $this->tableAliases is null.
+     *
+     * @return  array
+     */
+    public function getTableAliases()
+    {
+        if ($this->tableAliases === null) {
+            $this->tableAliases = $this->initializeTableAliases();
+        }
+
+        return $this->tableAliases;
+    }
+
+    /**
+     * Overwrite this in your repository implementation in case you need to initialize the table aliases lazily
+     *
+     * @return  array
+     */
+    protected function initializeTableAliases()
+    {
+        return array();
+    }
+
     /**
      * Remove each COLLATE SQL-instruction from all given query columns
      *
@@ -166,9 +204,11 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
     /**
      * Remove the datasource's prefix from the given table name and return the remaining part
      *
-     * @param   mixed   $table
+     * @param   array|string    $table
      *
-     * @return  mixed
+     * @return  array|string
+     *
+     * @throws  IcingaException         In case $table is not of a supported type
      */
     protected function removeTablePrefix($table)
     {
@@ -194,6 +234,45 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
         return $table;
     }
 
+    /**
+     * Return the given table with its alias being applied
+     *
+     * @param   array|string    $table
+     *
+     * @return  array|string
+     */
+    protected function applyTableAlias($table)
+    {
+        $tableAliases = $this->getTableAliases();
+        if (is_array($table) || !isset($tableAliases[($nonPrefixedTable = $this->removeTablePrefix($table))])) {
+            return $table;
+        }
+
+        return array($tableAliases[$nonPrefixedTable] => $table);
+    }
+
+    /**
+     * Return the given table with its alias being cleared
+     *
+     * @param   array|string    $table
+     *
+     * @return  string
+     *
+     * @throws  IcingaException         In case $table is not of a supported type
+     */
+    protected function clearTableAlias($table)
+    {
+        if (is_string($table)) {
+            return $table;
+        }
+
+        if (is_array($table)) {
+            return reset($table);
+        }
+
+        throw new IcingaException('Table alias handling for type "%s" is not supported', type($table));
+    }
+
     /**
      * Insert a table row with the given data
      *
@@ -323,11 +402,13 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
     /**
      * Validate that the requested table exists
      *
+     * This will prepend the datasource's table prefix and will apply the table's alias, if any.
+     *
      * @param   string              $table      The table to validate
      * @param   RepositoryQuery     $query      An optional query to pass as context
      *                                          (unused by the base implementation)
      *
-     * @return  string              The table's name, with the table prefix being prepended
+     * @return  array|string
      *
      * @throws  ProgrammingError                In case the given table does not exist
      */
@@ -338,7 +419,7 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
             $table = parent::requireTable($table);
         }
 
-        return $this->prependTablePrefix($table);
+        return $this->prependTablePrefix($this->applyTableAlias($table));
     }
 
     /**
@@ -373,7 +454,7 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
     /**
      * Return this repository's query columns of the given table mapped to their respective aliases
      *
-     * @param   mixed   $table
+     * @param   array|string    $table
      *
      * @return  array
      *
@@ -381,61 +462,48 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
      */
     public function requireAllQueryColumns($table)
     {
-        if (is_array($table)) {
-            $table = array_shift($table);
-        }
-
-        return parent::requireAllQueryColumns($this->removeTablePrefix($table));
+        return parent::requireAllQueryColumns($this->removeTablePrefix($this->clearTableAlias($table)));
     }
 
     /**
      * Return the query column name for the given alias or null in case the alias does not exist
      *
-     * @param   mixed   $table
-     * @param   string  $alias
+     * @param   array|string    $table
+     * @param   string          $alias
      *
      * @return  string|null
      */
     public function resolveQueryColumnAlias($table, $alias)
     {
-        if (is_array($table)) {
-            $table = array_shift($table);
-        }
-
-        return parent::resolveQueryColumnAlias($this->removeTablePrefix($table), $alias);
+        return parent::resolveQueryColumnAlias($this->removeTablePrefix($this->clearTableAlias($table)), $alias);
     }
 
     /**
      * Return whether the given query column name or alias is available in the given table
      *
-     * @param   mixed   $table
-     * @param   string  $column
+     * @param   array|string    $table
+     * @param   string          $column
      *
      * @return  bool
      */
     public function validateQueryColumnAssociation($table, $column)
     {
-        if (is_array($table)) {
-            $table = array_shift($table);
-        }
-
-        return parent::validateQueryColumnAssociation($this->removeTablePrefix($table), $column);
+        return parent::validateQueryColumnAssociation(
+            $this->removeTablePrefix($this->clearTableAlias($table)),
+            $column
+        );
     }
 
     /**
      * Return the statement column name for the given alias or null in case the alias does not exist
      *
-     * @param   mixed   $table
+     * @param   string  $table
      * @param   string  $alias
      *
      * @return  string|null
      */
     public function resolveStatementColumnAlias($table, $alias)
     {
-        if (is_array($table)) {
-            $table = array_shift($table);
-        }
-
         $statementColumnMap = $this->getStatementColumnMap();
         if (isset($statementColumnMap[$alias])) {
             return $statementColumnMap[$alias];
@@ -450,17 +518,13 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
     /**
      * Return whether the given alias or statement column name is available in the given table
      *
-     * @param   mixed   $table
+     * @param   string  $table
      * @param   string  $alias
      *
      * @return  bool
      */
     public function validateStatementColumnAssociation($table, $alias)
     {
-        if (is_array($table)) {
-            $table = array_shift($table);
-        }
-
         $statementTableMap = $this->getStatementTableMap();
         if (isset($statementTableMap[$alias])) {
             return $statementTableMap[$alias] === $this->removeTablePrefix($table);
@@ -473,7 +537,7 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
     /**
      * Return whether the given column name or alias of the given table is a valid statement column
      *
-     * @param   mixed   $table  The table where to look for the column or alias
+     * @param   string  $table  The table where to look for the column or alias
      * @param   string  $name   The column name or alias to check
      *
      * @return  bool
@@ -493,7 +557,7 @@ abstract class DbRepository extends Repository implements Extensible, Updatable,
     /**
      * Validate that the given column is a valid statement column and return it or the actual name if it's an alias
      *
-     * @param   mixed   $table      The table for which to require the column
+     * @param   string  $table      The table for which to require the column
      * @param   string  $name       The name or alias of the column to validate
      *
      * @return  string              The given column's name
diff --git a/library/Icinga/Repository/Repository.php b/library/Icinga/Repository/Repository.php
index 56f383f0c..7fba11727 100644
--- a/library/Icinga/Repository/Repository.php
+++ b/library/Icinga/Repository/Repository.php
@@ -48,7 +48,7 @@ abstract class Repository implements Selectable
      *
      * This will be automatically set to the first key of $queryColumns if not explicitly set.
      *
-     * @var mixed
+     * @var string
      */
     protected $baseTable;
 
@@ -196,7 +196,7 @@ abstract class Repository implements Selectable
     /**
      * Return the base table name this repository is responsible for
      *
-     * @return  mixed
+     * @return  string
      *
      * @throws  ProgrammingError    In case no base table name has been set and
      *                               $this->queryColumns does not provide one either