Ruby on Rails - Create a form with Multiple instances of the same model -

i have model, namely "bank_accounts", contains many users

i want use form list out users (while first name editable), 1 click of "submit" can gather users' first name.

-@bank_accounts.each |account|   =form_for account |f|     =f.text_field :first_name 

the code above gives

    <form class="edit_bank_accounts" id="edit_bank_account_1" action="/bank_account/1" accept-charset="utf-8" method="post">     <input type="text" value="123" name="bank_account[first_name]" id="bank_account_first_name"/>     </form> <form class="edit_bank_accounts" id="edit_bank_account_2" action="/bank_account/2" accept-charset="utf-8" method="post">     <input type="text" value="456" name="bank_account[first_name]" id="bank_account_first_name"/>     </form> 

but want

<form class="edit_bank_accounts" id="edit_bank_account" action="/bank_account" accept-charset="utf-8" method="post">     <input type="text" value="123" name="bank_account[1][first_name]" id="bank_account_first_name"/> <input type="text" value="456" name="bank_account[2][first_name]" id="bank_account_first_name"/>     </form> 

how generate bank_account[id][first_name] form in ruby on rails?

thanks.

move loop inside form tag

= form_tag '/bank_account', html: { id: 'edit_bank_accounts', class: 'edit_bank_accounts' }   -@bank_accounts.each |account|     = text_field_tag :bank_account_first_name, account.first_name, name: "bank_account[#{account.id}][first_name]"