APIv4 - Simplify bridge joins

This simplifies the code and improves efficiency by using an inner sub-join
instead of a subquery. The latter was trying to fake it, but this is the real
thing: joining on two tables as if they were a single table.

diff --git a/Civi/Api4/Query/Api4SelectQuery.php b/Civi/Api4/Query/Api4SelectQuery.php
index 8430da8794fb4a5363fa5803eda16814514e82a3..0ba463c33483d1878d2c4720855214bc9345914a 100644 (file)
--- a/Civi/Api4/Query/Api4SelectQuery.php
+++ b/Civi/Api4/Query/Api4SelectQuery.php
@@ -43,11 +43,6 @@ class Api4SelectQuery {
    */
   protected $query;
 
-  /**
-   * @var array
-   */
-  protected $joins = [];
-
   /**
    * Used to keep track of implicit join table aliases
    * @var array
@@ -870,12 +865,10 @@ class Api4SelectQuery {
   }
 
   /**
-   * Join via a Bridge table
+   * Join via a Bridge table using a join within a join
    *
    * This creates a double-join in sql that appears to the API user like a single join.
    *
-   * LEFT joins use a subquery so that the bridge + joined-entity can be treated like a single table.
-   *
    * @param array $joinTree
    * @param string $joinEntity
    * @param string $alias
@@ -886,52 +879,30 @@ class Api4SelectQuery {
     $bridgeEntity = array_shift($joinTree);
     $this->explicitJoins[$alias]['bridge'] = $bridgeEntity;
 
-    // INNER joins require unique aliases, whereas left joins will be inside a subquery and short aliases are more readable
-    $bridgeAlias = $side === 'INNER' ? $alias . '_via_' . strtolower($bridgeEntity) : 'b';
-    $joinAlias = $side === 'INNER' ? $alias : 'c';
+    $bridgeAlias = $alias . '_via_' . strtolower($bridgeEntity);
 
     $joinTable = CoreUtil::getTableName($joinEntity);
     [$bridgeTable, $baseRef, $joinRef] = $this->getBridgeRefs($bridgeEntity, $joinEntity);
 
-    $bridgeFields = $this->registerBridgeJoinFields($bridgeEntity, $joinRef, $baseRef, $alias, $bridgeAlias, $side);
+    $this->registerBridgeJoinFields($bridgeEntity, $joinRef, $baseRef, $alias, $bridgeAlias);
 
-    $linkConditions = $this->getBridgeLinkConditions($bridgeAlias, $joinAlias, $joinTable, $joinRef);
+    $linkConditions = $this->getBridgeLinkConditions($bridgeAlias, $alias, $joinTable, $joinRef);
 
     $bridgeConditions = $this->getBridgeJoinConditions($joinTree, $baseRef, $alias, $bridgeAlias, $bridgeEntity, $side);
 
-    $acls = array_values($this->getAclClause($joinAlias, CoreUtil::getBAOFromApiName($joinEntity), [NULL, NULL]));
+    $acls = array_values($this->getAclClause($alias, CoreUtil::getBAOFromApiName($joinEntity), [NULL, NULL]));
 
     $joinConditions = [];
     foreach (array_filter($joinTree) as $clause) {
       $joinConditions[] = $this->treeWalkClauses($clause, 'ON');
     }
 
-    // INNER joins are done with 2 joins
-    if ($side === 'INNER') {
-      // Info needed for joining custom fields extending the bridge entity
-      $this->explicitJoins[$alias]['bridge_table_alias'] = $bridgeAlias;
-      $this->explicitJoins[$alias]['bridge_id_alias'] = 'id';
-      $this->join('INNER', $bridgeTable, $bridgeAlias, $bridgeConditions);
-      $this->join('INNER', $joinTable, $alias, array_merge($linkConditions, $acls, $joinConditions));
-    }
-    // For LEFT joins, construct a subquery to link the bridge & join tables as one
-    else {
-      $joinEntityClass = CoreUtil::getApiClass($joinEntity);
-      foreach ($joinEntityClass::get($this->getCheckPermissions())->entityFields() as $name => $field) {
-        if ($field['type'] === 'Field') {
-          $bridgeFields[$field['column_name']] = '`' . $joinAlias . '`.`' . $field['column_name'] . '`';
-        }
-      }
-      // Info needed for joining custom fields extending the bridge entity
-      $this->explicitJoins[$alias]['bridge_table_alias'] = $alias;
-      $this->explicitJoins[$alias]['bridge_id_alias'] = 'bridge_entity_id_key';
-      $bridgeFields[] = "`$bridgeAlias`.`id` AS `bridge_entity_id_key`";
-      $select = implode(',', $bridgeFields);
-      $joinConditions = array_merge($joinConditions, $bridgeConditions);
-      $innerConditions = array_merge($linkConditions, $acls);
-      $subquery = "SELECT $select FROM `$bridgeTable` `$bridgeAlias`, `$joinTable` `$joinAlias` WHERE " . implode(' AND ', $innerConditions);
-      $this->query->join($alias, "$side JOIN ($subquery) `$alias` ON " . implode(' AND ', $joinConditions));
-    }
+    // Info needed for joining custom fields extending the bridge entity
+    $this->explicitJoins[$alias]['bridge_table_alias'] = $bridgeAlias;
+
+    $outerConditions = array_merge($joinConditions, $bridgeConditions);
+    $innerConditions = array_merge($linkConditions, $acls);
+    $this->query->join($alias, "$side JOIN (`$bridgeTable` AS `$bridgeAlias` INNER JOIN `$joinTable` AS `$alias` ON (" . implode(' AND ', $innerConditions) . ")) ON " . implode(' AND ', $outerConditions));
   }
 
   /**
@@ -995,27 +966,20 @@ class Api4SelectQuery {
    * @param $baseRef
    * @param string $alias
    * @param string $bridgeAlias
-   * @param string $side
-   * @return array
    */
-  private function registerBridgeJoinFields($bridgeEntity, $joinRef, $baseRef, string $alias, string $bridgeAlias, string $side): array {
-    $fakeFields = [];
+  private function registerBridgeJoinFields($bridgeEntity, $joinRef, $baseRef, string $alias, string $bridgeAlias): void {
     $bridgeFkFields = [$joinRef->getReferenceKey(), $joinRef->getTypeColumn(), $baseRef->getReferenceKey(), $baseRef->getTypeColumn()];
     $bridgeEntityClass = CoreUtil::getApiClass($bridgeEntity);
+    $bridgeIdColumn = CoreUtil::getIdFieldName($bridgeEntity);
     foreach ($bridgeEntityClass::get($this->getCheckPermissions())->entityFields() as $name => $field) {
-      if ($name === 'id' || ($side === 'INNER' && in_array($name, $bridgeFkFields, TRUE))) {
+      if ($name === $bridgeIdColumn || in_array($name, $bridgeFkFields, TRUE)) {
         continue;
       }
-      // For INNER joins, these fields get a sql alias pointing to the bridge entity,
-      // but an api alias pretending they belong to the join entity.
-      $field['sql_name'] = '`' . ($side === 'LEFT' ? $alias : $bridgeAlias) . '`.`' . $field['column_name'] . '`';
+      // Fields get a sql alias pointing to the bridge entity,
+      $field['sql_name'] = '`' . $bridgeAlias . '`.`' . $field['column_name'] . '`';
       $field['explicit_join'] = $alias;
       $this->addSpecField($alias . '.' . $name, $field);
-      if ($field['type'] === 'Field') {
-        $fakeFields[$field['column_name']] = '`' . $bridgeAlias . '`.`' . $field['column_name'] . '`';
-      }
     }
-    return $fakeFields;
   }
 
   /**
@@ -1026,13 +990,11 @@ class Api4SelectQuery {
    * @param string $alias
    * @param string $bridgeAlias
    * @param string $bridgeEntity
-   * @param string $side
    * @return string[]
    * @throws \CRM_Core_Exception
    */
-  private function getBridgeJoinConditions(array &$joinTree, $baseRef, string $alias, string $bridgeAlias, string $bridgeEntity, string $side): array {
+  private function getBridgeJoinConditions(array &$joinTree, $baseRef, string $alias, string $bridgeAlias, string $bridgeEntity): array {
     $bridgeConditions = [];
-    $bridgeAlias = $side === 'INNER' ? $bridgeAlias : $alias;
     // Find explicit bridge join conditions and move them out of the joinTree
     $joinTree = array_filter($joinTree, function ($clause) use ($baseRef, $alias, $bridgeAlias, &$bridgeConditions) {
       [$sideA, $op, $sideB] = array_pad((array) $clause, 3, NULL);
@@ -1148,9 +1110,6 @@ class Api4SelectQuery {
         if ($useBridgeTable) {
           // When joining custom fields that directly extend the bridge entity
           $baseTableAlias = $explicitJoin['bridge_table_alias'];
-          if ($link->getBaseColumn() === 'id') {
-            $link->setBaseColumn($explicitJoin['bridge_id_alias']);
-          }
         }
 
         // Cache field info for retrieval by $this->getField()
@@ -1194,12 +1153,8 @@ class Api4SelectQuery {
    * @param string $tableAlias
    * @param array $conditions
    */
-  public function join($side, $tableName, $tableAlias, $conditions) {
-    // INNER JOINs take precedence over LEFT JOINs
-    if ($side != 'LEFT' || !isset($this->joins[$tableAlias])) {
-      $this->joins[$tableAlias] = $side;
-      $this->query->join($tableAlias, "$side JOIN `$tableName` `$tableAlias` ON " . implode(' AND ', $conditions));
-    }
+  private function join(string $side, string $tableName, string $tableAlias, array $conditions): void {
+    $this->query->join($tableAlias, "$side JOIN `$tableName` `$tableAlias` ON " . implode(' AND ', $conditions));
   }
 
   /**