banki.test/controllers/ApiController.php

<?php

namespace app\controllers;
use app\models\Parameter;
use app\models\Image;
use yii\data\ActiveDataProvider;
use yii\rest\IndexAction;
use yii\web\NotFoundHttpException;
use yii\web\Request;
use yii\web\Response;

class ApiController extends \yii\rest\Controller
{
    public function actionIndex()
    {
        return Parameter::find()->with(['icon', 'iconGray'])->all();
    }

    public function actionImage(Request $request)
    {
        $img = Image::find()->where([ 'sha256' => $request->getQueryParam('sha256') ])->one();
        if (!$img) {
            throw new NotFoundHttpException();
        }

        \Yii::$app->response->format = Response::FORMAT_RAW;
        \Yii::$app->response->headers->set('Content-Type', $img->mime);
        return file_get_contents(env('UPLOADS_PATH') . '/' . $img->sha256);
    }

    public function verbs()
    {
        return [
            'index' => [ 'GET' ],
        ];
    }
}