Drop fields that has nil values (#148)

* drop nil values

* add test for drop nil values

* make the intention a bit clearer by changing `Enum.filter` to Enum.reject

* move drop_nil_values/1 to be used in params_for and params_with_assocs. rename v to value

* add test for params_with_assocs/2 for params without nil values

* rename drop_nil_values/1 to drop_fields_with_nil_values/1 and improve test naming

lib/ex_machina/ecto.ex

@@ -71,6 +71,7 @@ defmodule ExMachina.Ecto do
   def params_for(module, factory_name, attrs \\ %{}) do
     module.build(factory_name, attrs)
     |> drop_ecto_fields
+    |> drop_fields_with_nil_values
   end
 
   @doc """
@@ -90,6 +91,7 @@ defmodule ExMachina.Ecto do
     module.build(factory_name, attrs)
     |> insert_belongs_to_assocs(module)
     |> drop_ecto_fields
+    |> drop_fields_with_nil_values
   end
 
   defp insert_belongs_to_assocs(record = %{__struct__: struct, __meta__: %{__struct__: Ecto.Schema.Metadata}}, module) do
@@ -133,4 +135,10 @@ defmodule ExMachina.Ecto do
       {name, _type} -> Map.delete(map, name)
     end
   end
+
+  defp drop_fields_with_nil_values(map) do
+    map
+    |> Enum.reject(fn({_, value}) -> value == nil end)
+    |> Enum.into(%{})
+  end
 end

test/ex_machina/ecto_test.exs

@@ -52,6 +52,12 @@ defmodule ExMachina.EctoTest do
     end
   end
 
+  test "params_for/2 removes fields with nil values" do
+    assert TestFactory.params_for(:user, admin: nil) == %{
+      name: "John Doe"
+    }
+  end
+
   test "params_with_assocs/2 inserts belongs_tos that are set by the factory" do
     assert has_association_in_schema?(ExMachina.Article, :editor)
 
@@ -83,6 +89,14 @@ defmodule ExMachina.EctoTest do
     }
   end
 
+  test "params_with_assocs/2 removes fields with nil values" do
+    assert has_association_in_schema?(ExMachina.User, :articles)
+
+    assert TestFactory.params_with_assocs(:user, admin: nil) == %{
+      name: "John Doe",
+    }
+  end
+
   defp has_association_in_schema?(model, association_name) do
     Enum.member?(model.__schema__(:associations), association_name)
   end