# `Estructura.Transformer`
[🔗](https://github.com/am-kantox/estructura/blob/v1.13.0/lib/estructura/transformer.ex#L1)

# `t`

```elixir
@type t() :: term()
```

All the types that implement this protocol.

# `transform`

```elixir
@spec transform(t()) :: term()
```

The function returning the transformed input to be used with `Inspect` protocol.

This protocol is explicitly handful when deeply nested structs are to be logged/inspected.

```elixir
iex|%_{}|1 ▶ %Estructura.User{}
%Estructura.User{
  address: %Estructura.User.Address{
    city: nil,
    street: %Estructura.User.Address.Street{house: nil, name: []}
  },
  data: %Estructura.User.Data{age: nil},
  name: nil
}

iex|%_{}|2 ▶ Estructura.Transformer.transform %Estructura.User{}, type: false, except: ~w|address.street data.age|
[address: [city: nil], data: [], name: nil]
iex|%_{}|3 ▶ Estructura.Transformer.transform %Estructura.User{}, type: false, only: ~w|address.street data.age|
[address: [street: [house: nil, name: []]], data: [age: nil]]
iex|%_{}|4 ▶ Estructura.Transformer.transform %Estructura.User{}, only: ~w|address|
[
  *: Estructura.User,
  address: [
    *: Estructura.User.Address,
    city: nil,
    street: [*: Estructura.User.Address.Street, house: nil, name: []]
  ]
]
```

To enable it for your struct, use `@derive Estructura.Transformer` or
  `@derive {Estructura.Transformer, options}`. `Estructura` implementations derive it be default.

# `transform`

```elixir
@spec transform(
  t(),
  keyword()
) :: term()
```

---

*Consult [api-reference.md](api-reference.md) for complete listing*