Yii Framework is logged on the home page and cannot be detected on other pages

Yii Framework on the home page is logged in, no other pages detected login
if (Yii::app ()->user->getisguest ()) {
$blog _model=new Blog ();
$blog _model->content=$_post[' content ';
$blog _model->title=$_post[' title ';
Date_default_timezone_set (' UTC ');
$blog _model->time=date ("y-m-d h:i:s");

if ($blog _model->save ()) {
$this->redirect (site_url. ' Blog/index ');
$this->renderpartial (' success ');
}
}else{
$this->renderpartial (' Error ');
}

This is in the blog interface, to determine whether to login, login to allow posting, but always said I did not log in, has actually logged in, to find a solution
------to solve the idea----------------------
Session is automatically open, get a print look
------to solve the idea----------------------
Reference:

if (Yii::app ()->user->getisguest ()) {
$blog _model=new Blog ();
$blog _model->content=$_post[' content ';
$blog _model->title=$_post[' title ';
Date_default_timezone_set (' UTC ');
$blog _model->time=date ("y-m-d h:i:s");

if ($blog _model->save ()) {
$this->redirect (site_url. ' Blog/index ');
$this->renderpartial (' success ');
}
}else{
$this->renderpartial (' Error ');
}

This is in the blog interface, to determine whether to login, login to allow posting, but always said I did not log in, has actually logged in, to find a solution

Yii::app ()->user->getisguest This piece of code means if the user is a tourist ...

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