Which action hook should I use to intercept a form upon submission?

Im not entirely sure there is such action hook for custom forms (someone else might know) but there are definately other ways if form is submitted normally, without ajax.

Let me know if you have any questions.

//This applies if you want it to happen only if form is submited and page refreshed
//It doesn't work if user comes back later - there's no extra field later on

$form_submitted = false;

//If submit is pressed
if( isset( $_POST['submit'] ) ) {

    //There should also be a nonce check here

    $form_submitted = true;      
}

//All your form html here

//Check if form is submitted
if ( $form_submitted ) {

     //Show your extra fields
}



/*If you want it to be a bit more "permanent"

1. update_usermeta() to save the bool that user has submitted the form - logged-in users only
2. Use cookies which might not work properly in browser "stealth mode" and is gone if user deletes browser history with cookies 
3. Use sessions which destroys itselves if user closes the browser

*/

Related Posts:

  1. admin_post hook not working
  2. How to know what functions are hooked to an action/filter?
  3. Is there a hook that runs after a user logs in?
  4. Why do some hooks not work inside class context?
  5. Please explain how these hooks work
  6. Hook after image is uploaded and image sizes generated
  7. trigger save_post event programmatically
  8. My add_action (wp_footer, ‘method’) is not calling?
  9. How to check if which hook triggered the call to a function?
  10. is it possible to get the hook name in add_action?
  11. Run javascript code after wp_login hook?
  12. Redirect logged in users if they are on a specific page
  13. Check if action hook exists before adding actions to it
  14. Hooks are not executing
  15. after login that will redirect user role into a page
  16. add_action on inherit post status
  17. Detect type of post status transition
  18. Create hooks based on an array of hook names?
  19. Custom form action hook
  20. action lifecycle
  21. Is there a recover_post hook to go with trash_post hook?
  22. Redirect users on specific post category or category page
  23. How can i trigger an action manually?
  24. How to get post ID in post_updated action hook?
  25. Run add_action hook if condition
  26. Empty Super Cache programmatically (with ACF action) [closed]
  27. What is the best filter where to use register_block_type?
  28. How to send data from a form created by a plugin to an external API?
  29. How to use do_action_ref_array?
  30. Admin Hook at the Login Page
  31. Check if do_action(‘custom_action’) is hooked into?
  32. How to find hooks as per Just-In-Time approach?
  33. How To Make Sure That My Action Hook Executes Last
  34. Does update_comment_meta hook exists?
  35. how to determine how many and what kind of arguments are passed to hooks
  36. Hooking into the init action will fire it too frequently?
  37. Event-Driven Pattern vs MVC?
  38. Implement Hooks Using Array
  39. Save acf field data via acf/save_post before post is saved
  40. How do I trigger a post update within a get_posts() foreach loop?
  41. Hook when editing user
  42. Redirect in form handler causing form to be submitted twice
  43. schedule event in class oriented plugin
  44. Add action hook into wp_localize_script
  45. Hooks are not being removed in child theme
  46. How to replace a function using a child theme?
  47. Removing parent theme action on pluggable function not working
  48. Would there be anything stopping me from removing both wp_head and wp_footer?
  49. WordPress wp_loaded action hook
  50. add_action second argument missing
  51. I would like to send a notification email (Asana) whenever something is published (posts, pages, custom post types) [duplicate]
  52. admin_notices action doesn’t trigger within save_post action
  53. I don’t understand how add_action and do_action work in tandem. The former executes the code already…what is do_action for?
  54. Check if `do_action()` in WordPress returns any result
  55. How to cancel an action hooked to untrash_post? or any hook
  56. add_action hook for publish_post not working
  57. How to run a function after wp() in the wp-blog-header.php file?
  58. Hook for inserting?
  59. Notify admin when Custom post meta data gets updated or deletet
  60. dynamic add_action according to child pages (for homepage control)
  61. Remove action in a parent theme from the child theme
  62. Remove action within a class in a parent theme’s includes folder from the child theme
  63. Action hook with wrapper html
  64. What hook to add at start of WordPress load
  65. call php file from form and use wp functions
  66. A good hook to check authorization and redirect?
  67. Is there a author_update action?
  68. Change status of page after an event (Looking for best practice advice)
  69. Post via wp-admin and via iOS app, same hooks and triggers involved?
  70. Restrict editing of post type to list stored in user meta
  71. How to stop execution of a function via add_action hook?
  72. Can we change the hook firing sequence?
  73. changing genesis_before_while in new theme framework
  74. Rewrite the search page to use an appended slug + parameter
  75. Session management issues with WordPRess 404 Error page
  76. Struggling with plugin dev basics: add_action
  77. RTrouble passing arguments to action
  78. How to hook add_action() into after category description with id?
  79. remove_action not working for a function
  80. do_action not working in loop
  81. add_action doesn’t work for my function
  82. profile_update hook does not fire from front-end
  83. Add HTML code before the title of the Tag page
  84. How can I insert custom html code inside a div dynamically?
  85. How to trigger click events using hooks
  86. Hooks with same priority number. Can one stack items returned in divs, position: absolute each with their own z-index?
  87. Can add_image_size be added earlier
  88. Why does get_post() not return anything?
  89. WordPress save_post hook not firing when checking if _GET[‘post’] is set
  90. add hook restricted only to either plugins or themes?
  91. Using actions, hooks and filters in a non-WordPress page
  92. addaction hook cause redirection problem
  93. When is get_currentuserinfo() needed?
  94. How do I remove an action hook by s2member
  95. Which hook should I use for this scenario regarding the registration process and account/profile update?
  96. prepopulate form from a hook within wordpress function.php file
  97. Redirect back to origin page after using get_delete_post_link()
  98. add_action failed to display function by a plugin
  99. How do I set a custom post type Category after import using wp_set_post_terms
  100. Hooks to trigger a callback when adding, removing, rearranging or updating a widget in the widget area