query_util.exs

defmodule QueryUtil do
  def add_params_to_url(url, params) do
    url <> query_string(params)
  end

  defp query_string(params) do
    params |> Enum.map(&("#{&1.name}=#{&1.value}")) |> Enum.join("&")
  end
end

url = "http://example.com?"
params = [
  %{name: "test1", value: "value1"},
  %{name: "test2", value: "value2"}
]

result = QueryUtil.add_params_to_url(url, params)
IO.puts "result: #{inspect result}"

# ➜  ~  elixir query_util.exs
# result: "http://example.com?test1=value1&test2=value2"