Prevent direct access to a web page except redirect

Question

I have redirect to a web page upon successful form submission using guest plugin. The redirected page is in announcement tone so I'd like to prevent it from direct access with exception that comes from form submission.

Is there something Craft can do?

Answer 1

Add a Preparse field to the entry type you're posting to and make it generate a random string on entry save. Then make the Guest Entries plugin redirect to a URL with that Preparse field's value in the query string.

<input type="hidden" name="redirect" value="success?id={id}&key={preparseField}">

You should now be able to get that entry model in your template and test against that Preparse field's value.

{% set query = craft.request.getQuery() %}
{% set entry = craft.entries.id(query.id).preparseField(query.preparseField).first() %}

{% if not entry %}
    {% exit 404 %}
{% endif %}