Using ConfigurationBuilder and AddEnvironmentVariables it is not possible to make collection of values empty

[romfir]

Description

Using ConfigurationBuilder with AddEnvironmentVariables its not possible to make a collection empty, its only possible to make specific items null (using eg Some__Collection__0)

	Environment.SetEnvironmentVariable("Some__Collection", "{}"); //the same with empty string and "[]"
	
	var x = new ConfigurationBuilder()
				.AddJsonFile("test.json", optional: false, reloadOnChange: true)
//{
//		"Some": {
//			"Collection": [
//				"value1"
//			]
//		}
//	}				
				.AddEnvironmentVariables()
				.Build();
				
				x.GetSection("Some:Collection").Get<IEnumerable<string>>(); // always have value1

Reproduction Steps

Run code included in the description

Expected behavior

Add and document a way to make a collection empty using env variables

Actual behavior

Original values are always read

Regression?

No response

Known Workarounds

No response

Configuration

.NET 9
Microsoft.Extensions.Configuration: 9.0.1
Microsoft.Extensions.Configuration.EnvironmentVariables: 9.0.1
Microsoft.Extensions.Configuration.Json: 9.0.1

Other information

No response

[tarekgh]

Why do you need to define an empty collection in the first place? You can simply avoid defining it altogether or assign it an empty string. This way, the configuration will have a null collection, which you can easily check for.

[romfir]

I need to have a default value which is present in an appsettings file, but on one of the environments I want to make it empty (using envrionment variables defined inside docker compose file), of course I can add an additional setting EnableZxc, but I thought that removing all items from this collection would be cleaner.

assign it an empty string.

Assigning it to an empty string does not work, please see included code.

[tarekgh]

Assigning it to an empty string does not work, please see included code.

I mean having empty string value will make the read collection value is null which you can check for instead. I don't think we currently support defining empty collection in the environment variable provider.

[romfir]

but x.GetSection("Some:Collection").Get<IEnumerable<string>>() would still return all the items from the file, event when Some__Collection would be assisgned to an empty string, reading x.GetSection("Some:Collection").Get<string>() would return this empty string (not null) but this would require some manual checks on the consumer side.
Or are you perhaps talking about making items null via Some__Collection__0, Some__Collection__1 etc? Then yes this is a working workaround