Edit data form - how to append data outside of form during submission (e.g. id)

[cosmic rover]

HI, I have a dynamic object and only few properties of this object are part of edit form.

I need to merge old object data with form values, at first I tried to merge these in form onSubmit function - merge(oldData, ...parseFormData(formData))
Is there a better way without using hidden input fields?

[winged citrus]

Why do you need to do it client side?

You could let the user fill the new values, then in your action get the current data, append the new data and save the result