ecto returning nested validation errors

"errors": {
        "registration_number": [
            "can't be blank"
        ],
        "commanall": [
            {
                "email_id": [
                    "can't be blank"
                ],
                "contacts": [
                    {
                        "contact_number": [
                            "can't be blank"
                        ]
                    }
                ]
            }
        ]
    }

but we want response like

"errors": {
        "registration_number": ["can't be blank"],
	"email_id": ["can't be blank"],
       "contact_number": ["can't be blank"]
    }

this is my code

changeset_commanall = Commanall.changeset_company_contact(%Commanall{}, contact_params)
bothinsert = Ecto.Changeset.put_assoc(changeset, :commanall, [changeset_commanall])
Repo.insert(bothinsert)