I have a standard HTML form embedded in a PHP page that posts to an external Job Application API hosted and managed by a third party. The problem is that their form doesn't expect a load of $\_POST parameters as usual, but wants one single $\_POST parameter ('params') in the following format:

```
params="Prop2:title;Prop4:lastname;Prop6:firstname;"

```

And so on - there's about 30 fields.

How can I take the form inputs and convert to the single long string? Does this need some form of intermediary step between submit and post (In which case how would I put in the intermediary step?) or am I missing something more fundamental here?

The example form below works with a test textarea input with the required params presubmitted, but obviously ignores the actual firstname lastname inputs.

```
<form id="#applicationForm" method="POST" action="https://www.example.com/eternal-api">

  <input id="lastname" name="lastname" type="text" placeholder="Last name (Required)" class="input-xlarge" required="">
  <input id="firstname" name="firstname" type="text" placeholder="First Name (Required)" class="input-xlarge" required="">
  <textarea name="params" rows="2" cols="150">Prop4:Test_lastname;Prop6:test_firstname;</textarea>
  <input type="submit" value="Submit Application" class="btn btn-success">

</form>

```

To confuse matters, some of the inputs are upload fields, but I'll worry about that next!