Symfony ignore validation about extra fields

I need to add additional form fields dynamically with different names and ids to the form using angularJS. How do I make symfony ignore those fields when checking if the form is valid? I cant add those fields to the builder because I don't know what the names of the field will be. I could use form field naming including ID for example field1, field2, field3 and so on. but if so can I set a pattern of the field somehow? something like field*