Allow customizing through relations local keys (#89)

* Allow local keys for through relations

* Added local keys lookup for through relations

* Added local keys lookup usage

* Test get through relations with customized local keys

* Various improvements

* Fix backward compatibility

* Adjust method signature

---------

Co-authored-by: Jonas Staudenmeir <[email protected]>

Author: muhammedkamel

README.md

@@ -86,6 +86,30 @@ class Comment extends Model
 }
 ```
 
+You can specify custom local keys for the relations:
+
+`VendorCustomerAddress` → belongs to → `VendorCustomer` in `VendorCustomerAddress.vendor_customer_id`
+`VendorCustomerAddress` → belongs to → `CustomerAddress` in `VendorCustomerAddress.address_id`
+
+You can access `VendorCustomer` from `CustomerAddress` by the following
+
+```php
+class CustomerAddress extends Model
+{
+    use \Znck\Eloquent\Traits\BelongsToThrough;
+
+    public function vendorCustomer(): BelongsToThrough
+    {
+        return $this->belongsToThrough(
+            VendorCustomer::class,
+            VendorCustomerAddress::class,
+            foreignKeyLookup: [VendorCustomerAddress::class => 'id'],
+            localKeyLookup: [VendorCustomerAddress::class => 'address_id'],
+        );
+    }    
+}
+```
+
 ### Table Aliases
 
 If your relationship path contains the same model multiple times, you can specify a table alias (Laravel 6+):

src/Relations/BelongsToThrough.php

@@ -42,6 +42,13 @@ class BelongsToThrough extends Relation
      */
     protected $foreignKeyLookup;
 
+    /**
+     * The custom local keys on the relationship.
+     *
+     * @var array
+     */
+    protected $localKeyLookup;
+
     /**
      * Create a new belongs to through relationship instance.
      *
@@ -51,13 +58,23 @@ class BelongsToThrough extends Relation
      * @param string|null $localKey
      * @param string $prefix
      * @param array $foreignKeyLookup
+     * @param array $localKeyLookup
+     *
      * @return void
      */
-    public function __construct(Builder $query, Model $parent, array $throughParents, $localKey = null, $prefix = '', array $foreignKeyLookup = [])
-    {
+    public function __construct(
+        Builder $query,
+        Model $parent,
+        array $throughParents,
+        $localKey = null,
+        $prefix = '',
+        array $foreignKeyLookup = [],
+        array $localKeyLookup = []
+    ) {
         $this->throughParents = $throughParents;
         $this->prefix = $prefix;
         $this->foreignKeyLookup = $foreignKeyLookup;
+        $this->localKeyLookup = $localKeyLookup;
 
         parent::__construct($query, $parent);
     }
@@ -93,14 +110,14 @@ protected function performJoins(Builder $query = null)
 
             $first = $model->qualifyColumn($this->getForeignKeyName($predecessor));
 
-            $second = $predecessor->getQualifiedKeyName();
+            $second = $predecessor->qualifyColumn($this->getLocalKeyName($predecessor));
 
             $query->join($model->getTable(), $first, '=', $second);
 
             if ($this->hasSoftDeletes($model)) {
-                $column= $model->getQualifiedDeletedAtColumn();
+                $column = $model->getQualifiedDeletedAtColumn();
 
-                $query->withGlobalScope(__CLASS__ . ":$column", function (Builder $query) use ($column) {
+                $query->withGlobalScope(__CLASS__ . ":{$column}", function (Builder $query) use ($column) {
                     $query->whereNull($column);
                 });
             }
@@ -121,7 +138,24 @@ public function getForeignKeyName(Model $model = null)
             return $this->foreignKeyLookup[$table];
         }
 
-        return Str::singular($table).'_id';
+        return Str::singular($table) . '_id';
+    }
+
+    /**
+     * Get the local key for a model.
+     *
+     * @param \Illuminate\Database\Eloquent\Model $model
+     * @return string
+     */
+    public function getLocalKeyName(Model $model): string
+    {
+        $table = explode(' as ', $model->getTable())[0];
+
+        if (array_key_exists($table, $this->localKeyLookup)) {
+            return $this->localKeyLookup[$table];
+        }
+
+        return $model->getKeyName();
     }
 
     /**
@@ -225,7 +259,7 @@ public function getResults()
     public function first($columns = ['*'])
     {
         if ($columns === ['*']) {
-            $columns = [$this->related->getTable().'.*'];
+            $columns = [$this->related->getTable() . '.*'];
         }
 
         return $this->query->first($columns);
@@ -242,10 +276,10 @@ public function get($columns = ['*'])
         $columns = $this->query->getQuery()->columns ? [] : $columns;
 
         if ($columns === ['*']) {
-            $columns = [$this->related->getTable().'.*'];
+            $columns = [$this->related->getTable() . '.*'];
         }
 
-        $columns[] = $this->getQualifiedFirstLocalKeyName().' as '.static::THROUGH_KEY;
+        $columns[] = $this->getQualifiedFirstLocalKeyName() . ' as ' . static::THROUGH_KEY;
 
         $this->query->addSelect($columns);
 
@@ -264,7 +298,7 @@ public function getRelationExistenceQuery(Builder $query, Builder $parent, $colu
     {
         $this->performJoins($query);
 
-        $foreignKey = $parent->getQuery()->from.'.'.$this->getFirstForeignKeyName();
+        $foreignKey = $parent->getQuery()->from . '.' . $this->getFirstForeignKeyName();
 
         return $query->select($columns)->whereColumn(
             $this->getQualifiedFirstLocalKeyName(),
@@ -315,7 +349,7 @@ public function getThroughParents()
      */
     public function getFirstForeignKeyName()
     {
-        return $this->prefix.$this->getForeignKeyName(end($this->throughParents));
+        return $this->prefix . $this->getForeignKeyName(end($this->throughParents));
     }
 
     /**
@@ -325,7 +359,9 @@ public function getFirstForeignKeyName()
      */
     public function getQualifiedFirstLocalKeyName()
     {
-        return end($this->throughParents)->getQualifiedKeyName();
+        $lastThroughParent = end($this->throughParents);
+
+        return $lastThroughParent->qualifyColumn($this->getLocalKeyName($lastThroughParent));
     }
 
     /**

src/Traits/BelongsToThrough.php

@@ -16,13 +16,20 @@ trait BelongsToThrough
      * @param string|null $localKey
      * @param string $prefix
      * @param array $foreignKeyLookup
+     * @param array  $localKeyLookup
      * @return \Znck\Eloquent\Relations\BelongsToThrough
      */
-    public function belongsToThrough($related, $through, $localKey = null, $prefix = '', $foreignKeyLookup = [])
-    {
+    public function belongsToThrough(
+        $related,
+        $through,
+        $localKey = null,
+        $prefix = '',
+        $foreignKeyLookup = [],
+        array $localKeyLookup = []
+    ) {
         $relatedInstance = $this->newRelatedInstance($related);
-        $throughParents = [];
-        $foreignKeys = [];
+        $throughParents  = [];
+        $foreignKeys     = [];
 
         foreach ((array) $through as $model) {
             $foreignKey = null;
@@ -42,15 +49,41 @@ public function belongsToThrough($related, $through, $localKey = null, $prefix =
             $throughParents[] = $instance;
         }
 
-        foreach ($foreignKeyLookup as $model => $foreignKey) {
+        $foreignKeys = array_merge($foreignKeys, $this->mapKeys($foreignKeyLookup));
+
+        $localKeys = $this->mapKeys($localKeyLookup);
+
+        return $this->newBelongsToThrough(
+            $relatedInstance->newQuery(),
+            $this,
+            $throughParents,
+            $localKey,
+            $prefix,
+            $foreignKeys,
+            $localKeys
+        );
+    }
+
+    /**
+     * Map keys to an associative array where the key is the table name and the value is the key from the lookup.
+     *
+     * @param array $keyLookup
+     * @return array
+     */
+    protected function mapKeys(array $keyLookup): array
+    {
+        $keys = [];
+
+        // Iterate over each model and key in the key lookup
+        foreach ($keyLookup as $model => $key) {
+            // Create a new instance of the model
             $instance = new $model();
 
-            if ($foreignKey) {
-                $foreignKeys[$instance->getTable()] = $foreignKey;
-            }
+            // Add the table name and key to the keys array
+            $keys[$instance->getTable()] = $key;
         }
 
-        return $this->newBelongsToThrough($relatedInstance->newQuery(), $this, $throughParents, $localKey, $prefix, $foreignKeys);
+        return $keys;
     }
 
     /**
@@ -67,7 +100,7 @@ protected function belongsToThroughParentInstance($model)
         $instance = new $segments[0]();
 
         if (isset($segments[1])) {
-            $instance->setTable($instance->getTable().' as '.$segments[1]);
+            $instance->setTable($instance->getTable() . ' as ' . $segments[1]);
         }
 
         return $instance;
@@ -82,10 +115,18 @@ protected function belongsToThroughParentInstance($model)
      * @param string $localKey
      * @param string $prefix
      * @param array $foreignKeyLookup
+     * @param array $localKeyLookup
      * @return \Znck\Eloquent\Relations\BelongsToThrough
      */
-    protected function newBelongsToThrough(Builder $query, Model $parent, array $throughParents, $localKey, $prefix, array $foreignKeyLookup)
-    {
-        return new Relation($query, $parent, $throughParents, $localKey, $prefix, $foreignKeyLookup);
+    protected function newBelongsToThrough(
+        Builder $query,
+        Model $parent,
+        array $throughParents,
+        $localKey,
+        $prefix,
+        array $foreignKeyLookup,
+        array $localKeyLookup
+    ) {
+        return new Relation($query, $parent, $throughParents, $localKey, $prefix, $foreignKeyLookup, $localKeyLookup);
     }
 }

tests/BelongsToThroughTest.php

@@ -4,8 +4,10 @@
 
 use Tests\Models\Comment;
 use Tests\Models\Country;
+use Tests\Models\CustomerAddress;
 use Tests\Models\Post;
 use Tests\Models\User;
+use Tests\Models\VendorCustomer;
 
 class BelongsToThroughTest extends TestCase
 {
@@ -134,4 +136,14 @@ public function testGetThroughParents()
         $this->assertInstanceOf(User::class, $throughParents[0]);
         $this->assertInstanceOf(Post::class, $throughParents[1]);
     }
+
+    public function testGetThroughWithCustomizedLocalKeys()
+    {
+        $addresses = CustomerAddress::with('vendorCustomer')->get();
+
+        $this->assertEquals(41, $addresses[0]->vendorCustomer->id);
+        $this->assertEquals(42, $addresses[1]->vendorCustomer->id);
+        $this->assertInstanceOf(VendorCustomer::class, $addresses[1]->vendorCustomer);
+        $this->assertFalse($addresses[2]->vendorCustomer()->exists());
+    }
 }

tests/Models/CustomerAddress.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Tests\Models;
+
+use Znck\Eloquent\Relations\BelongsToThrough;
+
+class CustomerAddress extends Model
+{
+    public function vendorCustomer(): BelongsToThrough
+    {
+        return $this->belongsToThrough(
+            VendorCustomer::class,
+            VendorCustomerAddress::class,
+            foreignKeyLookup: [VendorCustomerAddress::class => 'id'],
+            localKeyLookup: [VendorCustomerAddress::class => 'customer_address_id'],
+        );
+    }
+}

tests/Models/VendorCustomer.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Tests\Models;
+
+class VendorCustomer extends Model
+{
+    //
+}

tests/Models/VendorCustomerAddress.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Tests\Models;
+
+class VendorCustomerAddress extends Model
+{
+    //
+}

tests/TestCase.php

@@ -9,8 +9,11 @@
 use PHPUnit\Framework\TestCase as Base;
 use Tests\Models\Comment;
 use Tests\Models\Country;
+use Tests\Models\CustomerAddress;
 use Tests\Models\Post;
 use Tests\Models\User;
+use Tests\Models\VendorCustomer;
+use Tests\Models\VendorCustomerAddress;
 
 abstract class TestCase extends Base
 {
@@ -61,6 +64,20 @@ protected function migrate()
             $table->unsignedInteger('custom_post_id')->nullable();
             $table->unsignedInteger('parent_id')->nullable();
         });
+
+        DB::schema()->create('vendor_customers', function (Blueprint $table) {
+            $table->increments('id');
+        });
+
+        DB::schema()->create('customer_addresses', function (Blueprint $table) {
+            $table->increments('id');
+        });
+
+        DB::schema()->create('vendor_customer_addresses', function (Blueprint $table) {
+            $table->increments('id');
+            $table->unsignedInteger('vendor_customer_id');
+            $table->unsignedInteger('customer_address_id');
+        });
     }
 
     /**
@@ -91,6 +108,17 @@ protected function seed()
         Comment::create(['id' => 34, 'post_id' => null, 'custom_post_id' => 21, 'parent_id' => 33]);
         Comment::create(['id' => 35, 'post_id' => null, 'custom_post_id' => 24, 'parent_id' => 34]);
 
+        VendorCustomer::create(['id' => 41]);
+        VendorCustomer::create(['id' => 42]);
+        VendorCustomer::create(['id' => 43]);
+
+        CustomerAddress::create(['id' => 51]);
+        CustomerAddress::create(['id' => 52]);
+        CustomerAddress::create(['id' => 53]);
+
+        VendorCustomerAddress::create(['id' => 61, 'vendor_customer_id' => 41, 'customer_address_id' => 51]);
+        VendorCustomerAddress::create(['id' => 62, 'vendor_customer_id' => 42, 'customer_address_id' => 52]);
+
         Model::reguard();
     }
 }