Undefined image array key that has been defined

[TechnoDiver]

I'm getting an undefined array key warning from an array key that has been defined like the other keys in the array.

The method call is as follows:

$post_obj->addNews(
            $_POST['title'], $_POST['content'], $_POST['category'], 
            $_POST['status'], $_POST['post_type'], $_POST['tags'], $_POST['post_image']
        );

The method and class are:

class Post {
        private $conn;
        private $user_obj;

        public function __construct($conn, $user) {
            $this->conn = $conn;
            $this->user_obj = new User($conn, $user);

        }

        public function addNews($title, $content, $category, $status, $type, $tags, $image) {
            if(!empty($title) && !empty($content)) {
                $title = strtoupper($title);
                $title = mysqli_real_escape_string($this->conn, $title);
                $content = nl2br($content);
                $content = mysqli_real_escape_string($this->conn, $content);
                $added_by = $this->user_obj->getUsername();
                $query = mysqli_query($this->conn, "SELECT top_cat_id FROM top_categories WHERE top_cat_title='$category'");
                $row = mysqli_fetch_array($query);
                $cat_id = $row['top_cat_id'];

                $insert_sql = mysqli_query($this->conn, "INSERT INTO news VALUES ('', '$title', '$content', '$added_by', '$category', '$cat_id', '$image', '$tags', '$status', '$type', '0', '0', '0', '0');");
            }
        }
    }

the relevant HTML is:

<div class="form-group">
    <label>Image</label>
    <input type="file" name="post_image" accept="image/*" onchange="preview_image(event)" value="Choose Image">
    <br>
    <label>Image Preview</label><br>
    <img class="img-rounded" id="output_image" width="150" height="150" />
</div>

The warning is an undefined array key on 'post_image'. But it's been defined like all the others. There's nothing I could find relevant to this and I'm lost. Is the problem because it's an image? I see no reason why 'post_image' remains undefined. If anyone feels like looking it over, I always appreciate the extra direction, I'm lost on this

[requinix]

File uploads do not go in $_POST. They go in $_FILES.

https://www.php.net/manual/en/features.file-upload.post-method.php

[kicken]

Uploaded files are in $_FILES, not $_POST.

[requinix]

Seconds apart and similarly phrased!

[TechnoDiver]

Alright, thanks. I knew about $_FILES but I didn't realize that the values didn't pass into $_POST too