yii2用表单上传文件经常用到的

1、单个文件上传

首先建立一个模型models/UploadForm.php,内容如下

<?php
namespace app\models;

use yii\base\Model;
use yii\web\UploadedFile;

/**
 * UploadForm is the model behind the upload form.
 */
class UploadForm extends Model
{
    /**
     * @var UploadedFile file attribute
     */
    public $file;

    /**
     * @return array the validation rules.
     */
    public function rules()
    {
        return [
            [['file'], 'file'],
        ];
    }
}
?>

再在对应的视图文件夹里建立一个视图（html）文件，内容如下:

<?php
use yii\widgets\ActiveForm;
?>

<?php $form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]) ?>

<?= $form->field($model, 'file')->fileInput() ?>

<button>Submit</button>

<?php ActiveForm::end() ?>

最后建立控制器文件，内容如下：

<?php
namespace app\controllers;

use Yii;
use yii\web\Controller;
use app\models\UploadForm;
use yii\web\UploadedFile;

class SiteController extends Controller
{
    public function actionUpload()
    {
        $model = new UploadForm();

        if (Yii::$app->request->isPost) {
            $model->file = UploadedFile::getInstance($model, 'file');

            if ($model->file && $model->validate()) {                
                $model->file->saveAs('uploads/' . $model->file->baseName . '.' . $model->file->extension);
            }
        }

        return $this->render('upload', ['model' => $model]);
    }
}
?>

注意这里我们没有用model->load(…)，而是用了UploadedFile::getInstance(…)。区别是后者不会执行model−>validate()，所以需要手动的去执行 model->validate()来检验数据的合法性。如果检验通过了，上传的文件保存在uploads文件夹下，即web目录下的uploads里。

一些可选的配置选项
上传文件不能为空

public function rules()
{
    return [
        [['file'], 'file', 'skipOnEmpty' => false],
    ];
}

上传类型，不仅可以根据扩展名检验，还可以根据文件的内容进行检验

public function rules()
{
    return [
        [['file'], 'file', 'extensions' => 'jpg, png', 'mimeTypes' => 'image/jpeg, image/png',],
    ];
}

2、多文件上传

如果你想一次上传多个文件，只需调节几个参数就可以达到目的

模型层（model）：

class UploadForm extends Model
{
    /**
     * @var UploadedFile|Null file attribute
     */
    public $file;

    /**
     * @return array the validation rules.
     */
    public function rules()
    {
        return [
            [['file'], 'file', 'maxFiles' => 10], // <--- here!
        ];
    }
}

视图层（view）:

<?php
use yii\widgets\ActiveForm;

$form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]);
?>

<?= $form->field($model, 'file[]')->fileInput(['multiple' => true]) ?>

    <button>Submit</button>

<?php ActiveForm::end(); ?>

与单文件上传不同的是下面这句:

$form->field($model, 'file[]')->fileInput(['multiple' => true])

控制器层（Controller）：

<?php
namespace app\controllers;

use Yii;
use yii\web\Controller;
use app\models\UploadForm;
use yii\web\UploadedFile;

class SiteController extends Controller
{
    public function actionUpload()
    {
        $model = new UploadForm();

        if (Yii::$app->request->isPost) {
            $model->file = UploadedFile::getInstances($model, 'file');

            if ($model->file && $model->validate()) {
                foreach ($model->file as $file) {
                    $file->saveAs('uploads/' . $file->baseName . '.' . $file->extension);
                }
            }
        }

        return $this->render('upload', ['model' => $model]);
    }
}
?>