Validates the given changeset looking for the cnpj field, it allows customization of lookup field and error messages.

Example

struct
|> cast(params, @fields)
|> validate_cnpj

It will look up for a field named :cnpj to acquire the value, if you do not use this name on field you can customize as second arity.

Example

 struct
 |> cast(params, @fields)
 |> validate_cnpj(:cadastro_juridico)