In chapter 2 page 48 identities are introduced and the following code is listed:

```
identities do
identity :unique_album_names_per_artist, [:name, :artist_id],
message: “already exists for this artist”
end
```

and in page 49 is mentioned that an error will be displayed when trying to enter an album with the same name. With the provided code the error is not shown, the option eager_check?: true must be added:

```
identities do
identity :unique_album_names_per_artist, [:name, :artist_id],
eager_check?: true,
message: “already exist for this artist”
end
```