Castable View Source

Protocol to aid casting unknown values to known value.

Example:

  defimpl Castable, for: MyStruct do
    def cast(_to, %{"foo" => foo}, _opts) when is_bitstring(foo) do
      %MyStruct{foo: foo}
    end

    def cast(_to, foo, _opts) when is_bitstring(foo) do
      %MyStruct{foo: foo}
    end

    def cast(_to, _from, _opts) do
      :error
    end
  end

  iex> Castable.cast(%MyStruct{}, %{"foo" => "bar"})
  %MyStruct{foo: "bar"}

  iex> Castable.cast(%MyStruct{}, "bar")
  %MyStruct{foo: "bar"}

  iex> Castable.cast(%MyStruct{}, 123)
  :error

Installation

If available in Hex, the package can be installed by adding castable to your list of dependencies in mix.exs:

def deps do
  [
    {:castable, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/castable.