feat(Formatters.String): allow overriding the number of decimals in float representation

CHANGELOG.md

@@ -1,3 +1,7 @@
+# Upcoming
+
+- allow overriding the number of decimals in float representation (`config :logster, Logster.Formatters.String, decimals: 5`)
+
 # 2.0.0-rc.3
 
 - `extra_fields` configuration to optionally enable `host` and `query_params` params being logged.

lib/logster/formatters/string.ex

@@ -13,7 +13,21 @@ defmodule Logster.Formatters.String do
   defp format_field(value), do: value
 
   defp format_value(value) when is_binary(value), do: value
-  defp format_value(value) when is_float(value), do: :erlang.float_to_binary(value, decimals: 3)
+
+  defp format_value(value) when is_float(value) do
+    config =
+      Application.get_env(:logster, __MODULE__) || []
+
+    opts =
+      if decimals = Keyword.get(config, :decimals, 3) do
+        [decimals: decimals]
+      else
+        [:short]
+      end
+
+    :erlang.float_to_binary(value, opts)
+  end
+
   defp format_value(value) when is_atom(value) or is_integer(value), do: to_string(value)
 
   defp format_value(value) when is_map(value) do

test/logster/formatters/string_test.exs

@@ -21,6 +21,26 @@ defmodule Logster.Formatters.StringTest do
     assert result == ~s(one=two foo=bar baz=123456 qux=123.457 xyz={"fi":"fo"} zzz={"one", "two"})
   end
 
+  test "can override the number of decimals for a string" do
+    old = Application.get_env(:logster, @formatter) || []
+
+    on_exit(fn ->
+      Application.put_env(:logster, @formatter, old)
+    end)
+
+    log = [bar: 123.4567]
+
+    Application.put_env(:logster, @formatter, Keyword.put(old, :decimals, 1))
+
+    result = log |> @formatter.format() |> IO.iodata_to_binary()
+    assert result == ~s(bar=123.5)
+
+    Application.put_env(:logster, @formatter, Keyword.put(old, :decimals, nil))
+
+    result = log |> @formatter.format() |> IO.iodata_to_binary()
+    assert result == ~s(bar=123.4567)
+  end
+
   test "formats field with a non-json convertible map" do
     result =
       [