<div align="center">
# `useful`
A collection of useful functions for building `Elixir` Apps.
[](http://codecov.io/github/dwyl/auth?branch=main)
[](https://hex.pm/packages/useful)
[](https://libraries.io/hex/useful)
[](https://github.com/dwyl/useful/issues)
[](http://hits.dwyl.com/dwyl/useful)
</div>
# Why? 🤷
We found ourselves copy-pasting a few useful "helper" functions
across our Elixir projects ... <br />
it wasn't
["DRY"](https://en.wikipedia.org/wiki/Don%27t_repeat_yourself),
so we created this library.
# What? 💭
A library of useful functions
that we reach for
when building `Elixir` Apps.
# Who? 👤
This library is used in our various `Elixir` / `Phoenix` apps. <br />
As with everything we do it's Open Source, Tested and Documented
so that _anyone_ can benefit from it.
# How? 💻
## Install ⬇️
Install by adding `useful` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:useful, "~> 1.10.0"}
]
end
```
## Function Reference
### `atomize_map_keys/1`
Converts a `Map` that has strings as keys (or mixed keys)
to have only atom keys. e.g:
```elixir
# map that has different types of keys:
my_map = %{"name" => "Alex", id: 1}
Useful.atomize_map_keys(my_map)
%{name: Alex, id: 1}
```
Works recursively for deeply nested maps:
```elixir
person = %{"name" => "Alex", id: 1, details: %{"age" => 17, height: 185}}
Useful.atomize_map_keys(person)
%{name: Alex, id: 1, details: %{age: 17, height: 185}}
```
### `flatten_map/1`
Flatten a `Map` of any depth/nesting:
```elixir
iex> map = %{name: "alex", data: %{age: 17, height: 185}}
iex> Useful.flatten_map(map)
%{data__age: 17, data__height: 185, name: "alex"}
```
**Note**: `flatten_map/1` converts all Map keys to `Atom`
as it's easier to work with atoms as keys
e.g: `map.person__name` instead of `map["person__name"]`.
We use the `__` (_double underscore_)
as the delimiter for the keys of nested maps,
because if we attempt to use `.` (_period character_)
we get an error:
```elixir
iex(1)> :a.b
** (UndefinedFunctionError) function :a.b/0 is undefined (module :a is not available)
:a.b()
```
### `get_in_default/1`
Get a deeply nested value from a map.
`get_in_default/3` Proxies `Kernel.get_in/2`
but allows setting a `default` value as the 3rd argument.
```elixir
iex> map = %{name: "alex", detail: %{age: 17, height: 185}}
iex> Useful.get_in_default(map, [:data, :age])
17
iex> Useful.get_in_default(map, [:data, :everything], "Awesome")
"Awesome"
iex> Useful.get_in_default(conn, [:assigns, :person, :id], 0)
0
```
We needed this for getting `conn.assigns.person.id`
in our [`App`](https://github.com/dwyl/mvp/)
without having to write a bunch of boilerplate!
e.g:
```elixir
person_id =
case Map.has_key?(conn.assigns, :person) do
false -> 0
true -> Map.get(conn.assigns.person, :id)
end
```
is just:
```elixir
person_id = Useful.get_in_default(conn, [:assigns, :person, :id], 0)
```
_Muuuuuuch cleaner/clearer_! 😍
If any of the keys in the list is not found
it doesn't _explode_ with errors,
simply returns the `default` value `0`
and continues!
> **Note**: Code inspired by:
[stackoverflow.com/questions/48781427/optional-default-value-for-get-in](https://stackoverflow.com/questions/48781427/optional-default-value-for-get-in-access-behavior-elixir/48781493#48781493) <br />
All credit to [**`@PatNowak`**](https://github.com/PatNowak) 🙌
The ideal syntax for this would be:
```elixir
person_id = conn.assigns.person.id || 0
```
But `Elixir` "_Me no likey_" ...
So this is what we have.
### `stringify_map/1`
Stringify a `Map` e.g. to store it in a DB or log it stdout.
```elixir
map = %{name: "alex", data: %{age: 17, height: 185}}
Useful.stringify_map(map)
"data__age: 17, data__height: 185, name: alex"
```
### `stringify_tuple/1`
Stringify a tuple of any length; useful in debugging.
```elixir
iex> tuple = {:ok, :example}
iex> Useful.stringify_tuple(tuple)
"ok: example"
```
### `typeof/1`
Returns the type of a variable, e.g: "function" or "integer"
Inspired by
[**`typeof`**](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof)
from `JavaScript` land.
```elixir
iex> myvar = 42
iex> Useful.typeof(myvar)
"integer"
```
### `empty_dir_contents/1`
Empties the directory
(_deletes all files and any nested directories_)
recursively, but does _not_ delete the actual directory.
This is useful when you want to reset a directory,
e.g. when testing.
```elixir
iex> dir = "tmp" # contains lots of sub directories and files
iex> Useful.empty_dir_contents(dir)
{:ok, dir}
```
<br />
# Docs 📜
Detailed docs available at:
https://hexdocs.pm/useful/Useful.html
<br />
# Help Us Help You! 🙏
If you need a specific helper function or utility
(e.g: something you found useful in a different programming language),
please
[open an issue](https://github.com/dwyl/useful/issues)
so that we can all benefit from useful functions.
Thanks!
