Add distinct()

Author: thekid

ChangeLog.md

@@ -3,7 +3,7 @@ MongoDB for XP Framework ChangeLog
 
 ## ?.?.? / ????-??-??
 
-* Added new method `Collection::count()` to count documents in a collection
+* Added new methods `Collection::distinct()` and `Collection::count()`
   (@thekid)
 * Added new method `Collection::aggregate()` to perform aggregations, see
   https://docs.mongodb.com/manual/reference/command/aggregate/ and

src/main/php/com/mongodb/Collection.class.php

@@ -89,7 +89,7 @@ public function find($filter= []): Cursor {
    * Count documents in this collection
    *
    * @param  [:var] $filter
-   * @return com.mongodb.result.Cursor
+   * @return int
    */
   public function count($filter= []): int {
     $result= $this->proto->msg(0, 0, [
@@ -100,6 +100,23 @@ public function count($filter= []): int {
     return $result['body']['n'];
   }
 
+  /**
+   * Returns distinct list of keys in this collection
+   *
+   * @param  string $key
+   * @param  [:var] $filter
+   * @return var[]
+   */
+  public function distinct($key, $filter= []): array {
+    $result= $this->proto->msg(0, 0, [
+      'distinct' => $this->name,
+      'key'      => $key,
+      'query'    => $filter ?: (object)[],
+      '$db'      => $this->database,
+    ]);
+    return $result['body']['values'];
+  }
+
   /**
    * Perfom aggregation over documents this collection
    *