从被调用函数访问时尝试获取非对象的属性

Question

I'm using yii framework but I think this is related to PHP

In my controller, I have the following code

$model = new Events;
    $model->type_id = $type_id;
    $checkFileUpload = checkFileUpload($model);

the function checkFileUpload is a custom function which contains

function checkFileUpload($model)
    {
        $rnd = rand(0, 9999);
        $uploadedFile = CUploadedFile::getInstance($model, 'image');
        if($uploadedFile->error == 0)
        { 
            $fileName = "{$rnd}-{$uploadedFile}";  // random number  file name
            $model->image = $fileName;
...

I got the error get property of non-object in $uploadedFile->error.

I've tried to use reference to the model instead, but it is deprecated and does not work for me.

If I use the code of the called function (checkFileUpload) within the controller code, it works fine. I suspect that object is not passed in a correct way.

Any help?

Answer 1

This is because your call to CUploadedFile::getInstance returns null and not the instance you desired.

Null is returned if no file is uploaded for the specified model attribute.

— Yii Documentation

It seems like your file was not correctly uploaded. I am not a Yii Framework user, but the documentation states:

The file should be uploaded using CHtml::activeFileField.

— Yii Documentation

So you should verify that the file was actually correctly uploaded with the proper method from the Yii Framework.

PS: Objects are always passed by reference.