Support json string on cast setter

src/Casts/SchemalessAttributes.php

@@ -32,6 +32,17 @@ public function get($model, $key, $value, $attributes)
      */
     public function set($model, $key, $value, $attributes)
     {
-        return json_encode($value);
+        return $this->isJson($value) ? $value : json_encode($value);
+    }
+
+    /**
+     * Verify that a variable is a json string
+     *
+     * @param  mixed  $value
+     * @return bool
+     */
+    function isJson($value): bool
+    {
+        return is_string($value) && str_starts_with($value, '{') && str_ends_with($value, '}');
     }
 }

tests/HasSchemalessAttributesTest.php

@@ -41,6 +41,14 @@ public function an_schemaless_attribute_can_be_set()
         $this->assertEquals('value', $this->testModel->schemaless_attributes->name);
     }
 
+    /** @test */
+    public function an_schemaless_attribute_can_be_set_from_json()
+    {
+        $this->testModel->schemaless_attributes = json_encode(['name' => 'value']);
+
+        $this->assertEquals('value', $this->testModel->schemaless_attributes->name);
+    }
+
     /** @test */
     public function it_can_determine_if_it_has_a_schemaless_attribute()
     {
@@ -245,6 +253,19 @@ public function it_can_add_and_save_schemaless_attributes_in_one_go()
         $this->assertEquals($array, $testModel->schemaless_attributes->all());
     }
 
+    /** @test */
+    public function it_can_and_save_schemaless_attributes_from_json()
+    {
+        $array = [
+            'name' => 'value',
+            'name2' => 'value2',
+        ];
+
+        $testModel = TestModel::create(['schemaless_attributes' => json_encode($array)]);
+
+        $this->assertEquals($array, $testModel->schemaless_attributes->all());
+    }
+
     /** @test */
     public function it_has_a_scope_to_get_models_with_the_given_schemaless_attributes()
     {