Getting ‘Undefined array key’ warning in editblog.php view page of CodeIgniter – how to resolve?

Can someone help to get out of this error as i have trapped in this error for a while,It’s became very much frustated for me to get out of this error.
Error is:

Update Blog

A PHP Error was encountered
Severity: Warning

Message: Undefined array key “blog_id”

Filename: blog/editblog.php

Line Number: 8

This is y editblog.php view page

load->view(‘Admin/header’); ?>

Update Blog

” method=”POST”>

Title:
“>

    <!-- by this for the form we can populate the data -->
    <div class="form-group">
        <b><label for="description" class="ms-5">Description:</label></b>
        <?php $textarea = array(
            'name'=>'desc',
            'id' =>'description',
            'value'=>set_value('desc',$blog['desc']),
            'rows'=>'5',
            'cols'=>'5',
            'class'=>'form-control mx-5'
        );
        echo form_textarea($textarea); ?>
        <p ><?= form_error('desc');?></p>

    </div>

    <br>    
    <div class="form-group">
        <b><label for="author" class="ms-5">Author:</label></b>
        <input type="text" class="form-control mx-5" name="author" value="<?= set_value('author',$blog['author']);?>" placeholder="Author of the blog">
        <p><?= form_error('author');?></p>

    </div>
    <br>

    <button class="btn btn-primary mx-5" name="submit" type="submit">Update</button>

</form>

load->view(‘Admin/footer’); ?>

This is my controller:

public function update_blog($blog_id)
{

    $this->load->model('blogmodel');

    $dataarr = $this->blogmodel->getdata($blog_id);
    $datalist = array();

    $datalist['blog'] = $dataarr;

    $this->load->library('form_validation');
    $this->form_validation->set_rules('title', 'Title of the blog', 'trim|required');
    $this->form_validation->set_rules('desc', 'description of the blog', 'trim|required');
    $this->form_validation->set_rules('author', 'author of the blog', 'trim|required');

    if ($this->form_validation->run() == false) {

        $this->load->view('Admin/blog/editblog', $datalist);
    } else {

        $data = array();
        $data['title'] = $this->input->post('title');
        $data['desc'] = $this->input->post('desc');
        $data['author'] = $this->input->post('author');
        $data['created_at'] = date('Y-m-d');
        $this->blogmodel->edit($blog_id, $data);
        $this->session->set_flashdata('success', 'Blog updated successfully');
        redirect('Blog/bloglist');
    }
}

Below is my model as blog_model.php

db->insert(‘blogs’,$formArray);
}

//fetching the all blogs records

public function getAllrecords() {
return $blogs = $this->db->get(‘blogs’)->result_array();
}

//updating the blogs

public function edit($blog_id,$data) {
$this->db->where(‘blog_id’,$blog_id);
$this->db->update(‘blogs’,$data);
}

//fetching one record with blogid

public function getdata($blog_id) {
$this->db->where(‘blog_id’,$blog_id);
$result = $this->db->get(‘blogs’)->result_array();
return $result;
}

function delete_blog($blog_id) {

$this->db->where(‘blog_id’,$blog_id);
$this->db->delete(‘blogs’);

}
}