Indifferent

This library provides a wrapper for indifferent access on maps, structs, lists and tuples.

You could use Indifferent to wrap a parameters hash or something without having to distingish on the type of keys (atoms or binaries) akin to the features of Rails' HashWithIndifferentAccess.

Installation

Available in Hex, the package can be installed as:

1. Add indifferent to your list of dependencies in mix.exs:

  def deps do
    [{:indifferent, "~> 0.9"}]
  end

2. Ensure indifferent is started before your application:

  def application do
    [applications: [:indifferent]]
  end

Usage

Be sure to look at the documentation for more examples.

Indifferent module

##
# Wrapping a map and accesing it with an atom key
iex> i = Indifferent.access(%{"a" => 1})
iex> i[:a]
1


##
# You can provide your custom list of key transformations
# and specify how are keys indifferents for your use case.
iex> i = Indifferent.access(%{"a" => 1},
...>   key_transforms: [fn x, _indifferent -> {:ok, String.downcase(x)} end])
iex> i["A"]
1

##
# Indifferent is compatible with Elixir's Access
iex> Kernel.get_in(%{"a" => 1}, [Indifferent.at(:a)])
1
iex> Kernel.get_in(Indifferent.access(%{"a" => 1}), [:a])
1

##
# Or you can auto wrap data by using Indifferent's version of
# `get_in/2`, `get_and_update_in/3`, `pop_in/2`
iex> Indifferent.get_and_update_in(%{"a" => %{"x" => 1}}, [:a, :x], fn x -> {x * 2, x * 4} end)
{2, %{"a" => %{"x" => 4}}}


##
# Indifferent `path/2` lets you use any syntax you want for
# accessing the nested value you need.
iex> %{"b" => %{"c" => %{"d" => %{"e" => 4}}}} |> Indifferent.path(b["c"][:d].e)
4

##
# And works on lists, tuples, keywords
iex> [9, %{"c" => {:ok, [e: 4]}}] |> Indifferent.path(1.c["1"].e)
4

##
# Accessing nil yields nil
iex> nil |> Indifferent.path(foo.bar)
nil

##
# Can access inside structs
iex> %User{name: "john"} |> Indifferent.path(name)
"john"

##
# And can be used with Kernel methods.
iex> Kernel.get_in(%{"a" => {0, 2}}, Indifferent.path(a["1"]))
2

##
# `path/2` can also take a Keyword of paths and returns a keyword of values
iex> %{"b" => [1, 2]} |> Indifferent.path(x: b[-1])
[x: 2]

##
# The `read/1` macro is a convenience that reads an indifferent path on the first value
iex> System.put_env("COLOR", "red")
iex> Indifferent.read(System.get_env.COLOR)
"red"

##
# Just like `path/2`, the `read/1` macro can also take a Keyword of named things to read
iex> System.put_env("COLOR", "red")
iex> Process.put(:color, "blue")
iex> Indifferent.read(a: System.get_env.COLOR, b: Process.get.color)
[a: "red", b: "blue"]

Indifferent sigils

The ~i and ~I sigils are shortcuts for the API previously described.

iex> import Indifferent.Sigils
Indifferent.Sigils

##
# `~i` is the sigil for `Indifferent.read/1`
iex> data = %{"a" => [b: {10, 20}]}
iex> ~i(data.a.b[1])
20

# When piped a value it will act just like `Indifferent.path/2`
iex> data = %{"a" => [b: {10, 20}]}
iex> data |> ~i(a.b[1])
20


##
# `~I` is the sigil version of `Indifferent.path/1`
# for use with Kernel access functions.

iex> data = %{"a" => [b: {10, 20}]}
iex> Kernel.get_in(data, ~I(a.b[1]))
20

iex> data = %{"a" => [b: {10, 20}]}
iex> Kernel.pop_in(data, ~I(a.b))
{{10, 20}, %{"a" => []}}