PersistConfig (Persist Config v0.4.14) View Source

Persists the configurations from a list of files during compilation. Also puts the current application name in a module attribute and provides a get_env macro for concise configuration value retrieval.

Installation

Add persist_config to your list of dependencies in mix.exs. Also include the required configuration files in the package definition of mix.exs:

def project do
  [
    app: :your_app,
    ...
    deps: deps(),
    package: package(),
    ...
  ]
end
...
def deps do
  [
    {:persist_config, "~> 0.4", runtime: false}
  ]
end
...
defp package do
  [
    files: ["lib", "mix.exs", "README*", "config/persist*.exs"],
    maintainers: [...],
    licenses: [...],
    links: %{...}
  ]
end

Usage

use PersistConfig supports the following options:

  • :app - module attribute to hold the current application name, defaults to :app
  • :files - wildcard paths, defaults to ["config/persist*.exs"]

Option :files selects the files whose configurations will be persisted. Each wildcard path is relative to the root. If no matching files are found, no configurations are persisted.

Although it is needless to do so, you can still import the configurations from the above matching files in config/config.exs or friends. For example:

import Config

import_config "persist_this_config.exs"

Even when your project is used as a dependency, this package will load and persist the configurations from the specified files during compilation.

For example, you may configure some path to read an external file and want to still read that very file when your app is a dependency (without and despite any path configuration in the parent app). To achieve this:

1. Use a module attribute as a constant:

use PersistConfig
...
@path get_env(:path)

2. Create a configuration file named, say, config/persist_path.exs:

import Config

config :words_cache, path: "#{File.cwd!()}/assets/words.txt"

3. In mix.exs, specify a package definition like this:

def project do
  [
    app: :words_cache,
    ...
    deps: deps(),
    package: package(),
    ...
  ]
end
...
def deps do
  [
    {:persist_config, "~> 0.4", runtime: false}
  ]
end
...
defp package do
  [
    files: [... "assets/words.txt", "config/persist*.exs"],
    maintainers: [...],
    licenses: [...],
    links: %{...}
  ]
end

Example 1

The current application name is in @app by default:

use PersistConfig, files: ["config/persist_path.exs"]
...
@all_env Application.get_all_env(@app)
@path get_env(:path)

Example 2

The current application name is in @my_app as an option:

use PersistConfig, app: :my_app
...
@my_attr Application.get_env(@my_app, :my_attr)

Example 3

You can use macro get_env to retrieve configuration values at runtime when configuration is done by config/config.exs and friends:

use PersistConfig
...
defp log?, do: get_env(:log?, true)

Link to this section Summary

Functions

Persists the configurations from a list of files during compilation. Also puts the current application name in a module attribute.

Returns the value for key in the current application's environment.

Link to this section Functions

Link to this macro

__using__(options \\ [])

View Source (macro)

Persists the configurations from a list of files during compilation. Also puts the current application name in a module attribute.

use PersistConfig supports the following options:

  • :app - module attribute to hold the current application name, defaults to :app
  • :files - wildcard paths, defaults to ["config/persist*.exs"]
Link to this macro

get_env(key, default \\ nil)

View Source (macro) (since 0.4.0)

Returns the value for key in the current application's environment.

If the configuration parameter does not exist, returns the default value.