Collapsible bootstrap, show first element

Question

I want to show the first element of this collapsible accordion. I did some research in internet but in vain

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" integrity="sha256-7s5uDGW3AHqw6xtJmNNtr+OBRJUlgkNJEo78P4b0yRw= sha512-nNo+yCHEyn0smMxSswnf/OnX6/KwJuZTlNZBjauKhTK0c+zT+q5JOCx0UFhXQ6rJR9jg6Es8gPuD2uZcYDLqSw==" crossorigin="anonymous">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js" integrity="sha256-KXn5puMvxCw+dAYznun+drMdG1IFl3agK0p/pqT9KAo= sha512-2e8qq0ETcfWRI4HJBzQiA3UoyFk6tbNyG+qSaIBZLyW9Xf3sWZHN/lxe9fTh1U45DpPf07yj94KsUHHWe4Yk1A==" crossorigin="anonymous"></script>

<div class="accordion" id="accordion2">
  <div class="accordion-group">
    <div class="accordion-heading">
      <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion2" href="#collapseOne" >
        Aller au dossier personnel d'un agent
      </a>
    </div>
    <div id="collapseOne" class="accordion-body collapse" style="height: 0px; ">
      <div class="accordion-inner">
        <form action="goToAgent.do" method="post">
          <p align="center">
            <input type="hidden" value="identite" name="retour">
            <label for="nomPrenom" >
              Entrer le nom complet de l'agent:
            </label>
            <input type="text" name="nomPrenom" class="typeahead" /> <br>
            <input type="submit" value="appliquer" class="btn btn-info" />
        </form>
      </div>
    </div>
  </div>
  <div class="accordion-group">
    <div class="accordion-heading">
      <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion2" href="#collapseTwo">
        Ajout d'un nouveau fonctionnaire
      </a>
    </div>
    <div id="collapseTwo" class="accordion-body collapse">
      <div class="accordion-inner">
        <!-- lorem -->
      </div>
    </div>
  </div>
</div>

Answer 1

You also can trigger a clic on the first collapse element

$("#accordion a:first").trigger("click");

Answer 2

Update for v4 :

The class .show can be used on the .collapse element to open it.

<div class="accordion" id="accordion-parent">
    <a data-toggle="collapse" href="#collapseOne"></a> 
    <div id="collapseOne" class="collapse show" data-parent="#accordion-parent"></div>
    <a data-toggle="collapse" href="#collapseTwo"></a> 
    <div id="collapseTwo" class="collapse" data-parent="#accordion-parent"></div>
</div>

Here's the same example working with v4 : Demo v4 (jsfiddle)

---

Bootstrap v2

If you add the .in class to the .collapse, it stays open :

<div class="accordion-group">  
  <div class="accordion-heading">  
    <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion2" href="#collapseTwo">  
     Ajout d'un nouveau fonctionnaire
    </a>  
  </div>  
  <div id="collapseTwo" class="accordion-body collapse in"> 
    <div class="accordion-inner">
    </div>  
  </div>  
</div>

Demo (jsfiddle)

---

Here is the demo with a simplified markup : http://jsfiddle.net/Sherbrow/yYuRz/2/

You do need to remove the style="height: 0px;" from the .collapse element if you want it to be displayed.