You are trying to implement nested form which is not supported in HTML.
Every form must be enclosed within a FORM element. There can be
several forms in a single document, but the FORM element can't be
nested.
Workaround
You can implement this functionality with some change in HTML and JavaScript. (without using html forms)
Steps
1. Create both forms with div tag as follows (do not use form tag)
<div id="form_a">
<input.../>
<div id="form_b">
<input.../>
<input.../>
<button id="submit_b">Submit B</button>
</div>
<input.../>
<button id="submit_a">Submit A</button>
</div >
2. Add JQuery and Ajax to submit each form data
<script>
// Submit form A data
$('#submit_a').click( function() {
$.ajax({
url: 'ajax-url',
type: 'post',
dataType: 'json',
data: $('#form_a input').not( "#form_b input" ).serialize(),
success: function(data) {
// ... do something with the data...
}
});
});
// Submit form B data
$('#submit_b').click( function() {
$.ajax({
url: 'ajax-url',
type: 'post',
dataType: 'json',
data: $('#form_b input').serialize(),
success: function(data) {
// ... do something with the data...
}
});
});
</script>