Added the ability to pass the alias as a string in the second parameter

Author: luisdalmolin

README.md

@@ -150,10 +150,21 @@ Sometimes, you are going to need to use table aliases on your joins because you
 Post::joinRelationshipUsingAlias('category.parent')->get();
 ```
 
-Or, you can also call the `as` function inside the join callback.
+In case you need to specify the name of the alias which is going to be used, you can do in two different ways:
+
+1. Passing a string as the second parameter (this won't work for nested joins):
+
+```php
+Post::joinRelationshipUsingAlias('category', 'category_alias')->get();
+```
+
+2. Calling the `as` function inside the join callback.
 
 ```php
 Post::joinRelationship('category.parent', [
+    'category' => function ($join) {
+        $join->as('category_alias');
+    },
     'parent' => function ($join) {
         $join->as('category_parent');
     },

src/PowerJoins.php

@@ -40,6 +40,7 @@ trait PowerJoins
     public function scopeJoinRelationship(Builder $query, $relationName, $callback = null, $joinType = 'join', $useAlias = false, bool $disableExtraConditions = false): void
     {
         $joinType = PowerJoins::$joinMethodsMap[$joinType] ?? $joinType;
+        $callback = $this->formatJoinCallback($relationName, $callback);
 
         if (is_null($query->getSelect())) {
             $query->select(sprintf('%s.*', $query->getModel()->getTable()));
@@ -385,4 +386,22 @@ public function clearPowerJoinCaches()
 
         return $this;
     }
+
+    /**
+     * Format the join callback.
+     *
+     * @param string $relationName
+     * @param mixed $callback
+     * @return mixed
+     */
+    protected function formatJoinCallback(string $relationName, $callback)
+    {
+        if (is_string($callback)) {
+            return function ($join) use ($callback) {
+                $join->as($callback);
+            };
+        }
+
+        return $callback;
+    }
 }

tests/JoinRelationshipTest.php

@@ -436,6 +436,28 @@ public function test_join_model_with_soft_deletes()
         );
     }
 
+    /** @test */
+    public function test_join_model_has_one_with_alias_and_select()
+    {
+        $profile = factory(UserProfile::class)->create();
+
+        $user = User::query()->select('profile.city')->leftJoinRelationship('profile', function ($join) {
+            $join->as('profile');
+        })->first();
+
+        $this->assertEquals($profile->city, $user->city);
+    }
+
+    /** @test */
+    public function test_join_with_alias_using_alias_as_string()
+    {
+        $innerJoinQuery = User::query()->select('profile.city')->joinRelationship('profile', 'p')->toSql();
+        $leftJoinQuery = User::query()->select('profile.city')->leftJoinRelationship('profile', 'p')->toSql();
+
+        $this->assertStringContainsString('inner join "user_profiles" as "p"', $innerJoinQuery);
+        $this->assertStringContainsString('left join "user_profiles" as "p"', $leftJoinQuery);
+    }
+
     /** @test */
     public function test_it_automatically_includes_select_statement_if_not_defined()
     {