Fixes #1791

framework/yii/db/ActiveQuery.php

@@ -247,20 +247,7 @@ class ActiveQuery extends Query implements ActiveQueryInterface
 			$with = [];
 		}
 
-		if (!empty($with)) {
-			$this->with = [];
-			foreach ($with as $name => $value) {
-				if (is_integer($name)) {
-					// repeating relation is fine as ActiveQueryTrait::normalizeRelations() handle it well
-					$this->with[] = $value;
-				} elseif (!isset($this->with[$name])) {
-					// with() takes precedence over joinWith() when both specify the same relation with callback
-					$this->with[$name] = $value;
-				}
-			}
-		}
-
-		return $this;
+		return $this->with($with);
 	}
 
 	/**

framework/yii/db/ActiveQueryTrait.php

@@ -93,15 +93,37 @@ trait ActiveQueryTrait
 	 * ])->all();
 	 * ~~~
 	 *
+	 * You can call `with()` multiple times. Each call will add relations to the existing ones.
+	 * For example, the following two statements are equivalent:
+	 *
+	 * ~~~
+	 * Customer::find()->with('orders', 'country')->all();
+	 * Customer::find()->with('orders')->with('country')->all();
+	 * ~~~
+	 *
 	 * @return static the query object itself
 	 */
 	public function with()
 	{
-		$this->with = func_get_args();
-		if (isset($this->with[0]) && is_array($this->with[0])) {
+		$with = func_get_args();
+		if (isset($with[0]) && is_array($with[0])) {
 			// the parameter is given as an array
-			$this->with = $this->with[0];
+			$with = $with[0];
 		}
+
+		if (empty($this->with)) {
+			$this->with = $with;
+		} elseif (!empty($with)) {
+			foreach ($with as $name => $value) {
+				if (is_integer($name)) {
+					// repeating relation is fine as normalizeRelations() handle it well
+					$this->with[] = $value;
+				} else {
+					$this->with[$name] = $value;
+				}
+			}
+		}
+
 		return $this;
 	}
 

tests/unit/framework/ar/ActiveRecordTestTrait.php

@@ -422,6 +422,16 @@ trait ActiveRecordTestTrait
 		$this->assertTrue($customer->isRelationPopulated('orders'));
 		$this->assertEquals(1, count($customer->orders));
 		$this->assertEquals(1, count($customer->relatedRecords));
+
+		// multiple with() calls
+		$orders = $this->callOrderFind()->with('customer', 'items')->all();
+		$this->assertEquals(3, count($orders));
+		$this->assertTrue($orders[0]->isRelationPopulated('customer'));
+		$this->assertTrue($orders[0]->isRelationPopulated('items'));
+		$orders = $this->callOrderFind()->with('customer')->with('items')->all();
+		$this->assertEquals(3, count($orders));
+		$this->assertTrue($orders[0]->isRelationPopulated('customer'));
+		$this->assertTrue($orders[0]->isRelationPopulated('items'));
 	}
 
 	public function testFindLazyVia()