Fix duplicate alias generation when joining same relationship multiple times (#214)

* Fix duplicate alias generation when joining same relationship multiple times

Replace time() with uniqid() in generateAliasForRelationship() to ensure unique aliases are generated even when called multiple times within the same second. This prevents later joins from overwriting earlier ones due to identical alias names.

* Fix test to be database-agnostic for MySQL compatibility

Update alias count check to handle both double quotes (PostgreSQL/SQLite) and backticks (MySQL) when counting table aliases in generated SQL.

Author: luisdalmolin

src/JoinsHelper.php

@@ -154,12 +154,12 @@ public function generateAliasForRelationship(Relation $relation, string $relatio
     {
         if ($relation instanceof BelongsToMany || $relation instanceof HasManyThrough) {
             return [
-                md5($relationName.'table1'.time()),
-                md5($relationName.'table2'.time()),
+                md5($relationName.'table1'.uniqid('', true)),
+                md5($relationName.'table2'.uniqid('', true)),
             ];
         }
 
-        return md5($relationName.time());
+        return md5($relationName.uniqid('', true));
     }
 
     /**

tests/DuplicateAliasGenerationTest.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace Kirschbaum\PowerJoins\Tests;
+
+use Kirschbaum\PowerJoins\JoinsHelper;
+use Kirschbaum\PowerJoins\Tests\Models\User;
+
+class DuplicateAliasGenerationTest extends TestCase
+{
+    /** @test */
+    public function test_multiple_joins_of_same_relationship_generate_unique_aliases()
+    {
+        $joinsHelper = JoinsHelper::make(new User());
+        $user = new User();
+        $relation = $user->posts();
+
+        // Generate multiple aliases for the same relationship quickly
+        $alias1 = $joinsHelper->generateAliasForRelationship($relation, 'posts');
+        $alias2 = $joinsHelper->generateAliasForRelationship($relation, 'posts');
+        $alias3 = $joinsHelper->generateAliasForRelationship($relation, 'posts');
+
+        // These should all be unique, but due to time() they will likely be the same
+        $this->assertNotEquals($alias1, $alias2, 'First and second aliases should be different');
+        $this->assertNotEquals($alias2, $alias3, 'Second and third aliases should be different');
+        $this->assertNotEquals($alias1, $alias3, 'First and third aliases should be different');
+    }
+
+    /** @test */
+    public function test_multiple_joins_of_same_belongs_to_many_relationship_generate_unique_aliases()
+    {
+        $joinsHelper = JoinsHelper::make(new User());
+        $user = new User();
+        $relation = $user->groups();
+
+        // Generate multiple aliases for the same BelongsToMany relationship quickly
+        $alias1 = $joinsHelper->generateAliasForRelationship($relation, 'groups');
+        $alias2 = $joinsHelper->generateAliasForRelationship($relation, 'groups');
+        $alias3 = $joinsHelper->generateAliasForRelationship($relation, 'groups');
+
+        // These should all be unique arrays, but due to time() they will likely be the same
+        $this->assertNotEquals($alias1, $alias2, 'First and second alias arrays should be different');
+        $this->assertNotEquals($alias2, $alias3, 'Second and third alias arrays should be different');
+        $this->assertNotEquals($alias1, $alias3, 'First and third alias arrays should be different');
+
+        // Also check individual elements
+        $this->assertNotEquals($alias1[0], $alias2[0], 'First elements of alias arrays should be different');
+        $this->assertNotEquals($alias1[1], $alias2[1], 'Second elements of alias arrays should be different');
+    }
+
+    /** @test */
+    public function test_actual_query_with_multiple_auto_generated_aliases_fails()
+    {
+        // This test demonstrates the real-world issue where multiple joins
+        // with auto-generated aliases can overwrite each other
+
+        $query = User::query()
+            ->joinRelationshipUsingAlias('posts')
+            ->joinRelationshipUsingAlias('posts'); // Second join of same relationship
+
+        $sql = $query->toSql();
+
+        // Count how many times "posts" appears with "as" in the SQL (database-agnostic)
+        $aliasCount = substr_count($sql, '"posts" as') + substr_count($sql, '`posts` as');
+
+        // We expect 2 different aliases, but due to the time() issue,
+        // we might get the same alias twice, resulting in only 1 unique join
+        $this->assertEquals(2, $aliasCount, 'Should have 2 different aliases for posts table, but got: '.$sql);
+    }
+}