ParamMap

Use atom keys to access values in string-keyed maps.

Unlike similar packages, ParamMap, does not blindly convert strings to atoms. It converts only the keys you specify.

The API is compatible with a subset of the Map module, which we are already familiar with.

If you use Ecto, maybe you know that as hard as we try, we can't help but read values from untrusted, string-keyed maps before they get normalized into an Ecto.Changeset. Changesets can be too heavy-handed for some situations.

Usage

iex> params = %{"color" => "red", "size" => "large", "age" => 100}

iex> ParamMap.get(params, :color)
"red"

iex> ParamMap.delete(params, :size)
%{"color" => "red", "age" => 100}

iex> ParamMap.take(params, [:color, :size])
%{color: "red", size: "large"}

iex> ParamMap.pop(params, :color)
{"red", %{"size" => "large", "age" => 100}}

## Still works with maps that have atom keys, in case you don't
## know ahead of time whether the keys are strings or atoms.

iex> params = %{:color => "red", "age" => 100}

iex> ParamMap.get(params, :color)
"red"

# The params may have a key both as a string and an atom.
# `get/1`, `pop/1`, and `take/2` prioritize the atom key.
# `delete/2`, `pop/1` remove both the atom and string version of the key.

iex> params = %{:color => "red", "color" => "blue"}

iex> ParamMap.get(params, :color)
"red"

iex> params = %{:color => "red", "color" => "blue", "age" => 100}

iex> ParamMap.delete(params, :color)
%{"age" => 100}

iex> params = %{:color => "red", "color" => "blue", "age" => 100}

iex> ParamMap.pop(params, :color)
{"red", %{"age" => 100}}

Installation

The package can be installed by adding param_map to your list of dependencies in mix.exs:

def deps do
  [
    {:param_map, "~> 0.1"}
  ]
end