Does Entries have relationship with User model? If so, you can pass cast_assoc to your changeset pipeline to do bulk insertion.

What do you intent to do with views? Do you want to display the returned data?
When generating a json api using mix phx.gen.json it generates similar to this:

  def render("index.json", %{contacts: contacts}) do
    %{data: render_many(contacts, ContactView, "contact.json")}
  end

  def render("show.json", %{contact: contact}) do
    %{data: render_one(contact, ContactView, "contact.json")}
  end

 def render("phone_number.json", %{number: number}) do
    %{id:  number.id, phone_number: number.phone_number}
 end

 def render("contact.json", %{contact: contact}) do
    %{id: contact.id,
       name: contact.name,
       phone_numbers: render_many(contact.numbers, ContactView, "phone_number.json")
    }
end

Make sure you know the shape of the returned data so you can structure the views.

Given the results:

[
 %Contact{
   id: 'something',
   name: 'some name',
   numbers: [
      %Number{id: 'some id', phone_number: 'some phone number'},
      %Number{id: 'some id', phone_number: 'some phone number'}
   ]
 },
%Contact{
   id: 'something',
   name: 'some name',
   numbers: [
      %Number{id: 'some id', phone_number: 'some phone number'},
      %Number{id: 'some id', phone_number: 'some phone number'}
   ]
 }
]

We can return its json format response like this:

with {:ok, entries} = Users.create_users(users_params) do
        conn
        |> render("contact.json", contact: entries)
end

Be sure to put an action_fallback to your controller so it can automatically handle changeset errors.

In the example I gave, it uses ContactView, in your case change the view name to your appropriate one.