aspnet/Microsoft.Extensions.Primitivesv10.0.1
✓ Verified.NET FW4.6.2.NET 10.0.NET 11.0.NET Std2.0
Primitives shared by framework extensions. Commonly used types include: Commonly Used Types: Microsoft.Extensions.Primitives.IChangeToken Microsoft.Extensions.Primitives.StringValues Microsoft.Extensions.Primitives.StringSegment
Get Started
$ dotnet add package Microsoft.Extensions.PrimitivesReadme
About
Microsoft.Extensions.Primitives contains isolated types that are used in many places within console or ASP.NET Core applications using framework extensions.
Key Features
- IChangeToken: An interface that represents a token that can notify when a change occurs. This can be used to trigger actions or invalidate caches when something changes. For example, the configuration and file providers libraries use this interface to reload settings or files when they are modified.
- StringValues: A struct that represents a single string or an array of strings. This can be used to efficiently store and manipulate multiple values that are logically a single value. For example, the HTTP headers and query strings libraries use this struct to handle multiple values for the same key.
- StringSegment: A struct that represents a substring of another string. This can be used to avoid allocating new strings when performing operations on parts of a string. For example, the configuration and logging libraries use this struct to parse and format strings.
How to Use
IChangeToken with configuration example
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Primitives;
using System;
class Program
{
static void Main(string[] args)
{
// Create a configuration builder
var configurationBuilder = new ConfigurationBuilder()
.SetBasePath(Environment.CurrentDirectory)
// appsettings.json expected to have the following contents:
// {
// "SomeKey": "SomeValue"
// }
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
// Build the configuration
IConfiguration configuration = configurationBuilder.Build();
// Create a change token for the configuration
IChangeToken changeToken = configuration.GetReloadToken();
// Attach a change callback
IDisposable changeTokenRegistration = changeToken.RegisterChangeCallback(state =>
{
Console.WriteLine("Configuration changed!");
IConfigurationRoot root = (IConfigurationRoot)state;
var someValue = root["SomeKey"]; // Access the updated configuration value
Console.WriteLine($"New value of SomeKey: {someValue}");
}, configuration);
// go and update the value of the key SomeKey in appsettings.json.
// The change callback will be invoked when the file is saved.
Console.WriteLine("Listening for configuration changes. Press any key to exit.");
Console.ReadKey();
// Clean up the change token registration when no longer needed
changeTokenRegistration.Dispose();
}
}