Refactor prepopulation

docs/en/04_Changelogs/4.3.0.md

@@ -4,6 +4,7 @@
 
  - `DataList::column()` now returns all values and not just "distinct" values from a column as per the API docs
  - `DataList`, `ArrayList` and `UnsavedRalationList` all have `columnUnique()` method for fetching distinct column values
+ - Take care with `stageChildren()` overrides. `Hierarchy::numChildren() ` results will only make use of `stageChildren()` customisations that are applied to the base class and don't include record-specific behaviour.
 
 ## Upgrading {#upgrading}
 

src/ORM/DB.php

@@ -430,6 +430,69 @@ public static function inline_parameters($sql, $parameters)
         return $joined;
     }
 
+
+    /**
+     * Replace 1 parameter with the given value
+     * For example, you can use this to replace a parameter with a column name instead of a literal
+     * @param string $sql The parameterised query
+     * @param int $paramIdx The 0-based position of the parameter
+     * @param array $replacement The value to insert into the queyr
+     * @param bool $skipEscaping Set to true to insert the value as-is, with no escaping. Use with caution!
+     *
+     * @return string
+     */
+    public static function replace_parameter($sql, $paramIdx, $replacement, $skipEscaping = false)
+    {
+        $segments = preg_split('/\?/', $sql);
+        $joined = '';
+        $inString = false;
+        $numSegments = count($segments);
+        $currentParamIdx = 0;
+
+        for ($i = 0; $i < $numSegments; $i++) {
+            $input = $segments[$i];
+            // Append next segment
+            $joined .= $segments[$i];
+            // Don't add placeholder after last segment
+            if ($i === $numSegments - 1) {
+                break;
+            }
+            // check string escape on previous fragment
+            // Remove escaped backslashes, count them!
+            $input = preg_replace('/\\\\\\\\/', '', $input);
+            // Count quotes
+            $totalQuotes = substr_count($input, "'"); // Includes double quote escaped quotes
+            $escapedQuotes = substr_count($input, "\\'");
+            if ((($totalQuotes - $escapedQuotes) % 2) !== 0) {
+                $inString = !$inString;
+            }
+
+            // Append placeholder replacement
+            if ($inString) {
+                // Literal question mark
+                $joined .= '?';
+                continue;
+            }
+
+            // If we've found the right parameter, replace it
+            if ($currentParamIdx == $paramIdx) {
+                if ($skipEscaping) {
+                    $value = $replacement;
+                } elseif (is_bool($replacement)) {
+                    $value = $replacement ? '1' : '0';
+                } elseif (is_int($replacement)) {
+                    $value = $replacement;
+                } else {
+                    $value = (DB::get_conn() !== null) ? Convert::raw2sql($replacement, true) : $replacement;
+                }
+                $joined .= $value;
+            }
+
+            $currentParamIdx++;
+        }
+        return $joined;
+    }
+
     /**
      * Execute the given SQL parameterised query with the specified arguments
      *

src/ORM/Hierarchy/Hierarchy.php

@@ -10,7 +10,10 @@
 use SilverStripe\ORM\ArrayList;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DataExtension;
+use SilverStripe\ORM\DB;
 use SilverStripe\Versioned\Versioned;
+use SilverStripe\Core\Config\Config;
+use SilverStripe\Core\Convert;
 use Exception;
 
 /**
@@ -71,6 +74,15 @@ class Hierarchy extends DataExtension
      */
     private static $hide_from_cms_tree = array();
 
+    /**
+     * Used to enable or disable the prepopulation of the numchildren cache.
+     * Defaults to true.
+     *
+     * @config
+     * @var boolean
+     */
+    private static $prepopulate_numchildren_cache = true;
+
     /**
      * Prevent virtual page virtualising these fields
      *
@@ -79,9 +91,17 @@ class Hierarchy extends DataExtension
      */
     private static $non_virtual_fields = [
         '_cache_children',
-        '_cache_numChildren',
     ];
 
+    /**
+     * A cache used by numChildren().
+     * Clear through {@link flushCache()}.
+     * version (int)0 means not on this stage.
+     *
+     * @var array
+     */
+    protected static $cache_numChildren = [];
+
     public static function get_extra_config($class, $extension, $args)
     {
         return array(
@@ -271,11 +291,18 @@ public function numHistoricalChildren()
      */
     public function numChildren($cache = true)
     {
-        // Load if caching
+
+        $baseClass = $this->owner->baseClass();
+        $cacheType = 'numChildren';
+        $id = $this->owner->ID;
+
+        // cached call
         if ($cache) {
-            $numChildren = $this->owner->_cache_numChildren;
-            if (isset($numChildren)) {
-                return $numChildren;
+            if (isset(self::$cache_numChildren[$baseClass][$cacheType][$id])) {
+                return self::$cache_numChildren[$baseClass][$cacheType][$id];
+            } elseif (isset(self::$cache_numChildren[$baseClass][$cacheType]['_complete'])) {
+                // If the cache is complete and we didn't find our ID in the cache, it means this object is childless.
+                return 0;
             }
         }
 
@@ -284,11 +311,117 @@ public function numChildren($cache = true)
 
         // Save if caching
         if ($cache) {
-            $this->owner->_cache_numChildren = $numChildren;
+            self::$cache_numChildren[$baseClass][$cacheType][$id] = $numChildren;
         }
+
         return $numChildren;
     }
 
+    /**
+     * Pre-populate any appropriate caches prior to rendering a tree.
+     * This is used to allow for the efficient rendering of tree views, notably in the CMS.
+     * In the cace of Hierarchy, it caches numChildren values. Other extensions can provide an
+     * onPrepopulateTreeDataCache(DataList $recordList = null, array $options) methods to hook
+     * into this event as well.
+     *
+     * @param DataList $recordList The list of records to prepopulate caches for. Null for all records.
+     * @param array $options A map of hints about what should be cached. "numChildrenMethod" and
+     *                       "childrenMethod" are allowed keys.
+     */
+    public function prepopulateTreeDataCache(DataList $recordList = null, array $options = [])
+    {
+        if (empty($options['numChildrenMethod']) || $options['numChildrenMethod'] === 'numChildren') {
+            $idList = $recordList ? $recordList->column('ID') : null;
+            self::prepopulate_numchildren_cache($this->owner->baseClass(), $idList);
+        }
+
+        $this->owner->extend('onPrepopulateTreeDataCache', $recordList, $options);
+    }
+
+    /**
+     * Pre-populate the cache for Versioned::get_versionnumber_by_stage() for
+     * a list of record IDs, for more efficient database querying.  If $idList
+     * is null, then every record will be pre-cached.
+     *
+     * @param string $class
+     * @param string $stage
+     * @param array $idList
+     */
+    public static function prepopulate_numchildren_cache($baseClass, $idList = null)
+    {
+        if (!Config::inst()->get(static::class, 'prepopulate_numchildren_cache')) {
+            return;
+        }
+
+        /** @var Versioned|DataObject $singleton */
+        $dummyObject = new $baseClass();
+        $dummyObject->ID = -23478234; // going to use this for search & replace
+        $baseTable = $dummyObject->baseTable();
+
+        $idColumn = Convert::symbol2sql("{$baseTable}.ID");
+        $parentIdColumn = Convert::symbol2sql("ParentID");
+
+
+        // Get the stageChildren() result of a dummy object and break down into a generic query
+        $query = $dummyObject->stageChildren(true)->dataQuery()->query();
+        $where = $query->getWhere();
+
+        $newWhere = [];
+
+        foreach ($where as $i => $compoundClause) {
+            foreach ($compoundClause as $clause => $params) {
+                // Skip any "WHERE ParentID = [marker]" clauses as this will be replaced with a GROUP BY
+                if (!(preg_match('/^"[^"]+"\."ParentID" = \?$/', $clause) && $clause[1] == $dummyObject->ID)) {
+                    // Replace any marker IDs with "<basetable>"."ID"
+                    $paramNum = 0;
+                    foreach ($params as $j => $param) {
+                        if ($param == $dummyObject->ID) {
+                            unset($params[$j]);
+                            $clause = DB::replace_parameter($clause, $paramNum, $parentIdColumn, true);
+                        } else {
+                            $paramNum++;
+                        }
+                    }
+
+                    $newWhere[] = [ $clause => $params ];
+                }
+            }
+        }
+
+        // optional ID-list filter
+        if ($idList) {
+            // Validate the ID list
+            foreach ($idList as $id) {
+                if (!is_numeric($id)) {
+                    user_error(
+                        "Bad ID passed to Versioned::prepopulate_numchildren_cache() in \$idList: " . $id,
+                        E_USER_ERROR
+                    );
+                }
+            }
+            $newWhere[] = ['"ParentID" IN (' . DB::placeholders($idList) . ')' => $idList];
+        }
+
+        $query->setWhere($newWhere);
+        $query->setOrderBy(null);
+
+        $query->setSelect([
+            '"ParentID"',
+            "COUNT(DISTINCT $idColumn) AS \"NumChildren\"",
+        ]);
+        $query->setGroupBy([
+            "ParentID
+        "]);
+
+        $numChildren = $query->execute()->map();
+        self::$cache_numChildren[$baseClass]['numChildren'] = $numChildren;
+        if (!$idList) {
+            // If all objects are being cached, mark this cache as complete
+            // to avoid counting children of childless object.
+            self::$cache_numChildren[$baseClass]['numChildren']['_complete'] = true;
+        }
+    }
+
     /**
      * Checks if we're on a controller where we should filter. ie. Are we loading the SiteTree?
      *
@@ -439,6 +572,6 @@ public function getBreadcrumbs($separator = ' &raquo; ')
     public function flushCache()
     {
         $this->owner->_cache_children = null;
-        $this->owner->_cache_numChildren = null;
+        self::$cache_numChildren = [];
     }
 }