added method withMath

Author: Alexmg86

README.md

@@ -14,6 +14,7 @@ I often use this in my work and I hope it will be useful to you!
 
 ## Last added
 
+2020/11/03 - Added method [withMath](https://github.com/Alexmg86/laravel-sub-query#working-with-columns)  
 2020/10/21 - Added [some sugar](https://github.com/Alexmg86/laravel-sub-query#sugar)  
 2020/10/06 - Added caching of [received data](https://github.com/Alexmg86/laravel-sub-query#caching)
 
@@ -115,6 +116,19 @@ By default, sorting is by `max` and `desc`, you can choose one of the options `m
 $invoices = Invoice::orderByRelation('items:price', 'asc', 'sum')->get();
 ```
 
+### Working with columns
+
+To add or multiply the required columns use this method:
+```php
+$items = Item::withMath(['invoice_id', 'price'])->get();
+echo $items[0]->sum_invoice_id_price;
+```
+Columns will be summed by default, you can choose one of the options `+`, `-`, `*`, `/` and set a new name.
+```php
+$items = Item::withMath(['invoice_id', 'price', 'price2'], '*', 'new_column')->get();
+echo $items[0]->new_column;
+```
+
 ### Load latest or oldest relation
 
 Imagine you want to get a list of 50 accounts, each with 100 items. By default, you will get 5000 positions and select the first ones for each account. PHP smokes nervously on the sidelines.  

src/Traits/LaravelSubQuerySugar.php

@@ -49,4 +49,46 @@ public function castColumn($column, $type = null)
         }
         return $this;
     }
+
+    /**
+     * Column math
+     * @param  string[]    $columns
+     * @param  string      $operator
+     * @param  string|null $name
+     * @return $this
+     */
+    public function withMath($columns, $operator = '+', $name = null)
+    {
+        $default = [
+            '+' => 'sum_',
+            '-' => 'sub_',
+            '*' => 'multi_',
+            '/' => 'div_'
+        ];
+
+        if (!is_array($columns) || count($columns) < 2) {
+            return $this;
+        }
+
+        if (is_null($this->query->columns)) {
+            $this->query->select([$this->query->from . '.*']);
+        }
+
+        $query = [];
+        foreach ($columns as $column) {
+            $query[] = $this->query->from . "." . $column;
+        }
+        $query = implode(" $operator ", $query);
+
+        $asName = implode('_', $columns);
+        if ($name) {
+            $asName = $name;
+        } elseif (array_key_exists($operator, $default)) {
+            $asName = $default[$operator] . $asName;
+        } else {
+            $asName = 'custom_' . $asName;
+        }
+
+        return $this->addSelect(new Expression("$query as $asName"));
+    }
 }

tests/LaravelSubQuerySugarTest.php

@@ -5,6 +5,7 @@
 use Alexmg86\LaravelSubQuery\Facades\LaravelSubQuery;
 use Alexmg86\LaravelSubQuery\ServiceProvider;
 use Alexmg86\LaravelSubQuery\Tests\Models\Invoice;
+use Alexmg86\LaravelSubQuery\Tests\Models\Item;
 
 class LaravelSubQuerySugarTest extends DatabaseTestCase
 {
@@ -68,4 +69,21 @@ public function testCastColumn()
 
         $this->assertEquals(111, $results->name);
     }
+
+    public function testWithMaths()
+    {
+        Item::create(['invoice_id' => 1, 'price' => 2, 'price2' => 5]);
+
+        $results = Item::withMath(['price', 'price2'])->first();
+
+        $this->assertEquals(7, $results->sum_price_price2);
+
+        $results = Item::withMath(['price', 'price2'], '*')->first();
+
+        $this->assertEquals(10, $results->multi_price_price2);
+
+        $results = Item::withMath(['price', 'price2'], '*', 'multi')->first();
+
+        $this->assertEquals(10, $results->multi);
+    }
 }

tests/Models/Item.php

@@ -2,10 +2,13 @@
 
 namespace Alexmg86\LaravelSubQuery\Tests\Models;
 
+use Alexmg86\LaravelSubQuery\Traits\LaravelSubQueryTrait;
 use Illuminate\Database\Eloquent\Model;
 
 class Item extends Model
 {
+    use LaravelSubQueryTrait;
+
     public $table = 'items';
     public $timestamps = false;
     protected $guarded = ['id'];