Elixir - increment a field value in Ecto map

I am getting two maps to a function.

Map1 is a list of maps

Map2 is a single map

I have to Enum.each this Map1 and marge with Map2(Which is static) and then insert in to database

This is working fine for me

Map example before inserting in to Database

%{
  api_id: 1,
  category_id: 2,
  content_url: "SeC9UPNoND8",
  sub_category_id: 1
}
%{
  api_id: 1,
  category_id: 2,
  content_url: "4wb8AYt3ECM",
  sub_category_id: 1
}
%{
  api_id: 1,
  category_id: 2,
  content_url: "2TSdkYkapo8",
  sub_category_id: 1
}

  def store_in_db(Map1, Map2) do
    
    Enum.each(Map1, fn(data) -> 
      Map.merge(data, Map2)
        |> Contents.create_content
      end)

  end

But now i got one new field to be added which is an just an increment $i++. which must be stored in priority field. For example in Map1 list i have got 3 maps. So i need below output

%{
  api_id: 1,
  category_id: 2,
  content_url: "SeC9UPNoND8",
  priority: 1,
  sub_category_id: 1
}
%{
  api_id: 1,
  category_id: 2,
  content_url: "4wb8AYt3ECM",
  priority: 2,
  sub_category_id: 1
}
%{
  api_id: 1,
  category_id: 2,
  content_url: "2TSdkYkapo8",
  priority: 3,
  sub_category_id: 1
}

I have done this

  def store_in_db(Map1, Map2) do
    
    Enum.each(Map1, fn(data) -> 
      Map.merge(data, Map2)
        |> Map.merge(%{priority: 1})
        |> Contents.create_content
      end)

  end

In that i want to increment priority value. Can someone give me insight on how to achieve this