I would like to create a form which can have fields like

Product Name :
Product ID :

and Save button, when user creates a new record on web form using HTML all the fields above should have blank values, however if they save existing records it should populate the data of that rerord jusing json URL.

Also it should validate the form without refreshing and while when they click on existing record it should use bootstrap modal window which eventully should populate the all the saved data for that record.

Can anyone please help me on how to go on this ?