CustomEnvironmentConfig

Enables binding environment variables and/or environment files to classes.

Changelog

07/08/2020 [v1.4.1]
- Added support for enums.

Examples

(.env [environment variables])

MyConfigItem=Test Value
Subclass_MyConfigSubItem=Test Subitem Value

(MyConfiguration.cs)

public class MyConfiguration 
{
    public string MyConfigItem { get; set; }
    
    public MyConfigSubClass Subclass { get; set; }
}

public class MyConfigSubClass 
{
    public string MyConfigSubItem { get; set; }
}

(Program.cs)

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                   .UseEnvironmentConfiguration<MyConfiguration>()               
            .....

(Startup.cs)

public class Startup 
{
    private readonly MyConfiguration _configuration;
    
    public Startup(MyConfiguration configuration) 
    {
        _configuration = configuration;
    }
    
    public void ConfigureServices(IServiceCollection services)
    {
        ...
        Console.WriteLine(_configuration.MyConfigItem);
        Console.WriteLine(_configuration.Subclass.MyConfigSubItem);
        ...
    }
}

If you want, you can re-map the name of the items using [ConfigurationItem]: (Do note, [ConfigurationItem] is not required and only needed if you want to set the requirement policy of a property or change the name of the environment variable)

public class MyConfiguration
{
    [ConfigurationItem("MyItem")]
    public bool Item { get; set; }
    // OR
    [ConfigurationItem(Name = "MyOtherItem")]
    public int OtherItem { get; set; }
    
    [ConfigurationItem("Test")
    public SubConfiguration MySubClass { get; set; }
}
public class SubConfiguration
{
    [ConfigurationItem]
    public bool SubItem { get; set; }
}

If you want to ignore parsing certain properties in a class, you can use [ConfigurationItem(Ignore = true)]:

public class MyConfiguration
{
    [ConfigurationItem("MyItem")]
    public bool Item { get; set; }
    
    public int OtherItem { get; set; }
    
    [ConfigurationItem(Ignore = true)]
    public SubConfiguration MySubClass { get; set; }
}

The environment variables for this would look like as follows:

MyItem=Value
MyOtherItem=Value
Test_SubItem=Value

You can also set if the item is required to be set in the environment or not. By default, items are required.

public class MyConfiguration
{
    [ConfigurationItem(Required = false)]
    public bool NotRequiredItem { get; set; }
    // OR
    [ConfigurationItem(Name = "MyOtherItem", Required = true)]
    public int OtherItem { get; set; }
}

If you want to specify a default value for an item if it's not required:

public class MyConfiguration
{
    [ConfigurationItem(Required = false, Default = true)]
    public bool NotRequiredItem { get; set; }
    // OR
    [ConfigurationItem(Required = false, Default = 123)]
    public int OtherItem { get; set; }
}

Conversions across types are supported for defaults, for instance:

(string)"123" => (int)123
(string)"true" => (bool)True
(string)"false" => (bool)False
(int)1 => (bool)True
(int)0 => (bool)False
...etc

From an Env File:

Most of this applies from above, except instead your IWebHostBuilder would look like:

// Program.cs
public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                   .UseEnvironmentConfiguration<MyConfiguration>(fileName: "filename.env", configurationTypeEnum: ConfigurationTypeEnum.PreferEnvironment)               
            .....

Non-DI:

To parse environment variables directly:

public void MyFunction() 
{
    var output = ConfigurationParser.Parse<MyClass>();
    // Access your class via output variable
}

To parse from an environment file:

public void MyFunction() 
{
    var output = ConfigurationParser.Parse<MyClass>(fileName: "file.env");
    // Access your class via output variable
}

Preferences

You can choose one of the following preferences:

• Prefer Environment Over File
• Prefer File Over Environment
• Use Environment Only
• Use File Only

The default functionality is Prefer Environment over File.

To use this functionality, there's two ways, both DI and non-DI:

DI

// Program.cs
public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                   .UseEnvironmentConfiguration<MyConfiguration>(fileName: "filename.env", configurationTypeEnum: ConfigurationTypeEnum.PreferEnvironment)               
            .....

Non-DI

public void MyFunction() 
{
    var output = ConfigurationParser.Parse<MyClass>(fileName: "file.env", configurationTypeEnum: ConfigurationTypeEnum.PreferEnvironment);
    .....
}

Manual-DI (for non asp.net core projects)

public void Main() 
{
    var servicesBuilder = new ServiceCollection();

    var output = ConfigurationParser.Parse<MyClass>(fileName: "file.env", configurationTypeEnum: ConfigurationTypeEnum.PreferEnvironment);
    servicesBuilder.AddSingleton(output);

    var services = servicesBuilder.BuildServiceProvider();

    // Access MyClass in constructor or like below
    var config = services.GetService<MyClass>();
    .....
}