Add ability to use Closure as a sortable parameter in table's column

app/tests/Unit/SpladeQueryBuilderTest.php

@@ -2,8 +2,11 @@
 
 namespace Tests\Unit;
 
+use App\Models\Address;
 use Illuminate\Database\Query\Builder;
+use Illuminate\Support\Facades\DB;
 use ProtoneMedia\Splade\SpladeQueryBuilder;
+use ProtoneMedia\Splade\SpladeTable;
 use Tests\TestCase;
 
 class SpladeQueryBuilderTest extends TestCase
@@ -21,4 +24,23 @@ public function it_can_parse_terms()
         $this->assertEquals(['0'], $builder->parseTermsIntoCollection('0')->all());
         $this->assertEquals(['1'], $builder->parseTermsIntoCollection('1')->all());
     }
+
+    /** @test */
+    public function it_can_apply_sorting_with_a_closure()
+    {
+        $table = SpladeTable::for(Address::class)
+            ->column('two_columns', sortable: function ($builder, $direction) {
+                $builder->orderBy('address', $direction)
+                    ->orderBy('city', $direction);
+            })
+            ->defaultSort('two_columns');
+
+        DB::enableQueryLog();
+        $table->beforeRender();
+        DB::disableQueryLog();
+        $log = DB::getQueryLog();
+
+        $this->assertCount(1, $log);
+        $this->assertEquals('select * from "addresses" order by "address" asc, "city" asc', $log[0]['query']);
+    }
 }

src/SpladeQueryBuilder.php

@@ -194,6 +194,10 @@ private function applyConstraint(array $columns, string $terms)
      */
     private function applySorting(Column $column)
     {
+        if (is_callable($column->sortable)) {
+            return ($column->sortable)($this->builder, $column->sorted);
+        }
+
         if (!$column->isNested()) {
             // Not a relationship, just a column on the table.
             return $this->builder->orderBy($column->key, $column->sorted);

src/Table/Column.php

@@ -20,7 +20,7 @@ public function __construct(
         public string $label,
         public bool $canBeHidden,
         public bool $hidden,
-        public bool $sortable,
+        public bool|Closure $sortable,
         public bool|string $sorted,
         public bool $highlight,
         public bool|Closure $exportAs,
@@ -60,7 +60,7 @@ public function toArray()
             'label'         => $this->label,
             'can_be_hidden' => $this->canBeHidden,
             'hidden'        => $this->hidden,
-            'sortable'      => $this->sortable,
+            'sortable'      => $this->sortable !== false,
             'sorted'        => $this->sorted,
             'highlight'     => $this->highlight,
         ];

src/Table/HasColumns.php

@@ -2,6 +2,7 @@
 
 namespace ProtoneMedia\Splade\Table;
 
+use Closure;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Str;
 
@@ -48,7 +49,7 @@ public function column(
         string $label = null,
         bool|null $canBeHidden = null,
         bool $hidden = false,
-        bool $sortable = false,
+        bool|Closure $sortable = false,
         bool|string $searchable = false,
         bool|null $highlight = null,
         bool|callable $exportAs = true,