That’s what https://hexdocs.pm/elixir/Kernel.html#struct/2 does.

This is dangerous as it doesn’t check that the keys in map_defaults actually correspond to keys of the struct. You may end up with a broken struct which is annoying to debug. What you should do is:

s = struct!(User, map_defaults)

This will ensure that keys that are in @enforce_keys must be exist and there are no keys that don’t exist in the struct. Otherwise it will raise an error. There is also Kernel.struct/2 (i.e. without exlamation mark) that will just discard unknown keys and won’t enforce @enforce_keys.

Untested, but it seems like cast and apply_changes should do what you want:

%User{} |> Ecto.Changeset.cast(map, User.__schema__(:fields)) |> Ecto.Changeset.apply_changes()