Question

I’m developing project on rails 2.3.8 and I need to get selected item on dropdown menu in model dialog box. Please can someone explain how to do it on model dialog box on rails ?

Answer 1

An example which will work with some adjustment, as you have given no code (give code and people will be able to give specific answers):

In the view something like this is produced by a form helper:

<select id="user_role_ids" name="user[role_ids]">
<option value="1" selected="selected">Reader</option>
<option value="2">Author</option>
</select>
<div id="role_output"></div>

In JS with jquery something like this to extract name or id of model in select:

<script type="text/javascript" charset="utf-8">
$("select").change(function () {
    var text = $('#user_role_ids option:selected').text()
    var value = $('#user_role_ids option:selected').val()
    $('#role_output').html(text+" =>"+value)
});
</script>

No need to involve rails at all unless you want to trigger an action in the controller as well, in which case post from jquery to an action set up specifically for it rather than extracting values:

$.post('/controller/my_action', ...);

That is all that observe_field does, and depending on what you want, you may not need it.