如何让错误消息仅在发送 $_POSTS 后出现？

Question

On a blog I'm coding the admin can edit existing posts.

I want to let an error -message appear when the $_POST['title'] for eg is empty(There will be displayed:"Your post should have a title"). I also do it if the subheading, content or category are empty.

The errors work just fine if one or some of them is/are empty. As soon I load the page to edit a post every error is displayed from the beginning.

How do I make them only appear when one or some $_POST's are empty after the <input type="submit .../> is clicked (they shouldn't be there when the site has loaded)?

This is the function in the PostsAdminController.php that checks the $_POST's and renders the site:

public function edit()
{
  $error = "";
  $id = $_GET['id'];
  $entry = $this->postsRepository->find($id);
  $categoryFId = $this->categoryRepository->getOneCatFromId($entry->c_Id);
  $savedSuccess = false;
  $abort = false;

  if ($this->loginService->check()) {
    if (!empty($_POST['title'])) {
      $entry->title = $_POST['title'];
    } else {
      $error .= "Your post should have a title.";
      $abort = true;
    }
    if (!empty($_POST['subheading'])) {
      $entry->subheading = $_POST['subheading'];
    } else {
      $error .= "A good subheading is nothing you should just leave out.";
      $abort = true;
    }
    if (!empty($_POST['content'])) {
      $entry->content = $_POST['content'];
    } else {
      $error .= "Your post should have content, you know, it wouldn't be a 'post' then.";
      $abort = true;
    }
    if (!empty($_POST['category'])) {
      $entry->c_Id = $_POST['category'];
    }
    if ($abort == false){
      $this->postsRepository->update($entry);
      $savedSuccess = true;
    }

  } else {
    $error = "You have no permission to do this, how the hell did you get here?";
  }

  $this->render("post/admin/edit", [
    'entry' => $entry,
    'error' => $error,
    'savedSuccess' => $savedSuccess,
    'categoryFId' => $categoryFId
  ]);
}

I really hope someone can help me with this, I don't know what I could to to let them only disappear when the POSTS have already been send..

Answer 1

You have to check if there was a POST action use:

if ($_SERVER['REQUEST_METHOD'] == 'POST')

in your case

...
if ($this->loginService->check()) {
    if ($_SERVER['REQUEST_METHOD'] == 'POST') {
       if (!empty($_POST['title'])) {
       ...
       }
    }
}