front end publishing not working on front-end page

Question

I have a custom front end publishing form on my website, based on this article.

It works perfectly when I put this code inside a page, but when on the front-end page (homepage), it doesn't work, and when I submit the form, I'm redirected to an archive.php page, the archive page from the post_category I've chosen in my form.

  'post_category' =>  array($_POST['cat'])

  <!-- post Category -->
  <fieldset class="category">
    <label for="cat">Catégorie :</label>
    <?php wp_dropdown_categories( 'tab_index=10&taxonomy=category&hide_empty=0&show_option_all=Choisissez une catégorie' ); ?>
  </fieldset>

anyone knows why it works on every other pages, but not on front page ?

here is my php code :

  <?php
if( 'POST' == $_SERVER['REQUEST_METHOD'] && !empty( $_POST['action'] ) &&  $_POST['action'] == "new_post") {

  // Do some minor form validation to make sure there is content
  if (isset ($_POST['title'])) {
    $title =  $_POST['title'];
  } else {
    echo 'veuillez entrer un titre';
  }
  if (isset ($_POST['description'])) {
    $description = $_POST['description'];
  } else {
    echo 'veuillez entrer du texte';
  }

  $genre = $_POST['genre'];
  $tranche_age = $_POST['tranche_age'];

  // ADD THE FORM INPUT TO $new_post ARRAY
  $new_post = array(
  'post_title'  =>  $title,
  'post_content'  =>  $description,
  'post_category' =>  array($_POST['cat']), // Usable for custom taxonomies too
  //'tax_input' => array( 'regions' => '14' ),
  'post_status' =>  'publish',           // Choose: publish, preview, future, draft, etc.
  'post_type' =>  'post',  //'post',page' or use a custom post type if you want to
  //'genre'  =>  $genre,
  //'tranche_age'  =>  $tranche_age,
  );


  //SAVE THE POST
  $pid = wp_insert_post($new_post);



  wp_set_post_terms($pid,array($_POST['regions']),'regions',true);
  wp_set_post_terms($pid,array($_POST['sexes']),'sexes',true);
  wp_set_post_terms($pid,array($_POST['ages']),'ages',true);


  //REDIRECT TO THE NEW POST ON SAVE
  $link = site_url();
  wp_redirect( $link );

  //ADD OUR CUSTOM FIELDS
  //add_post_meta($pid, 'genre', $genre, true); 
  //add_post_meta($pid, 'tranche_age', $tranche_age, true); 


} // END THE IF STATEMENT THAT STARTED THE WHOLE FORM

//POST THE POST YO
do_action('wp_insert_post', 'wp_insert_post');

?>

    <div id="container">
      <div id="content" role="main">

    <!-- FRONT END PUBLISHING -->

    <div class="wpcf7">
    <form id="new_post" name="new_post" method="post" action="" class="wpcf7-form" enctype="multipart/form-data">
      <!-- post name -->
      <fieldset name="name">
        <label for="title">Titre:</label>
        <input type="text" id="title" value="" tabindex="5" name="title" />
      </fieldset>

      <!-- post Category -->
      <fieldset class="category">
        <label for="cat">Catégorie :</label>
        <?php wp_dropdown_categories( 'tab_index=10&taxonomy=category&hide_empty=0&show_option_all=Choisissez une catégorie' ); ?>
      </fieldset>

      <!-- post regions -->
      <fieldset class="regions">
        <label for="regions">Région :</label>
        <?php wp_dropdown_categories( 'name=regions&tab_index=10&taxonomy=regions&hide_empty=0&show_option_all=Choisissez une catégorie' ); ?>
      </fieldset>

      <!-- post Content -->
      <fieldset class="content">
        <label for="description">Question :</label>
        <textarea id="description" tabindex="14" name="description" cols="80" rows="10"></textarea>
      </fieldset>

      <!-- Genre -->
      <input type="hidden" id="sexes" name="sexes" value="26" />


      <!-- Tranche d'âge -->
        <?php $date_of_birth = um_user('birth_date'); $age =  CalculateAge($date_of_birth); ?>

        <?php if ($age >= 18 && $age <= 25) :?>

        <input type="hidden" value="28" id="ages" name="ages" />

        <?php endif; ?>

        <?php if ($age >= 26 && $age <= 35) :?>

        <input type="hidden" value="29" id="ages" name="ages" />

        <?php endif; ?>

        <?php if ($age >= 36 && $age <= 45) :?>

        <input type="hidden" value="30" id="ages" name="ages" />

        <?php endif; ?>

        <?php if ($age >= 46) :?>

        <input type="hidden" value="31" id="ages" name="ages" />

        <?php endif; ?>





      <fieldset class="submit">
        <input type="submit" value="Envoyer" tabindex="40" id="submit" name="submit" />
      </fieldset>

      <input type="hidden" name="action" value="new_post" />
      <?php wp_nonce_field( 'new-post' ); ?>
    </form>
</div>

</div>
</div>

Answer 1

thanks to @TheDeadMedic, I found the solution. I used reserved terms, and that's why Wordpress interpreted my inputs as query parameters.

so for example with my categorys, I had to change my classes in my form :

  'post_category' =>  array($_POST['cat']), // Usable for custom taxonomies too

by

  'post_category' =>  array($_POST['my_cat']), // Usable for custom taxonomies too

and in my form the class name "cat" by "my_cat".

I had to change this every time I used a reserved term.

and now it works perfectly fine !