Library Overview

This library enables applications to dynamically load and update configurations from a relational database. It supports automatic refresh intervals and manual reloading of settings, ensuring that your application can adapt to configuration changes on-the-fly without restarting or redeploying the application.

Features

• Dynamic Configuration Loading: Load key/value pairs from a relational database to manage application settings.
• Automatic Refresh: Configure a reload timer to refresh settings automatically at specified intervals.
• Manual Reload Option: Manually trigger a reload of settings to ensure the application can quickly adapt to configuration changes.
• Customizable Schema: Flexibly define the database schema, table, and column names to fit your existing database structure.

Preparing Your Database

First, ensure your database includes a table for storing configuration key/value pairs. The default expected table structure is as follows:

CREATE TABLE Settings (
    Key VARCHAR(255) NOT NULL,
    Value VARCHAR(255),
    PRIMARY KEY (Key)
);

Library Setup

Basic Configuration

1. Establish Database Connection: Begin by creating a DbConnection instance using your database connection string. This connection will be used to load settings from the database.

   var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
   var dbConnection = new SqlConnection(connectionString);

2. Add Database Configuration to Your Application: Integrate the database settings into your application's configuration system.

   builder.Configuration.AddDatabase(dbConnection);

Advanced Configuration

For advanced scenarios, you can customize the default behavior by specifying additional options:

builder.Configuration.AddDatabase(dbConnection, option =>
{
    option.Schema = "cfg"; // Default is empty.
    option.Table = "Configurations"; // Default is "Settings".
    option.KeyColumn = "K"; // Default is "Key".
    option.ValueColumn = "V"; // Default is "Value".
    option.AutoReload = new TimeSpan(0, 0, 0, 20); // Set auto-reload interval for every 20 seconds. Default is no auto reload (zero).
});

Using Configuration in Your Application

Register Configuration Classes

1. Define Configuration POCO: Create a class representing your configuration settings, mapping each property to a specific configuration key.

   public sealed class Site
   {
       public string Name { get; init; } // Maps to Site:Name in the database
   }

2. Register and Set in DI: Register your configuration class with the Dependency Injection (DI) container and set it up for use within your application.

   builder.Services.Configure<Site>(builder.Configuration.GetSection("Site"));

Accessing Configurations

• Utilize IOptionsSnapshot to access the latest configuration values within your application components, ensuring you can react to changes in configuration dynamically.

  public class MyController : ControllerBase
  {
      private readonly IOptionsSnapshot<Site> _settingsSnapshot;
  
      public MyController(IOptionsSnapshot<Site> settingsSnapshot)
      {
          _settingsSnapshot = settingsSnapshot;
      }
  }

• Access configuration values through the _settingsSnapshot instance. For example, if your database has a record with Key: Site:Name and Value: www.google.com, you can retrieve this value using _settingsSnapshot.Value.Name.

Refreshing Configuration

• Automatic Refresh: If AutoReload is set, the library will automatically refresh configuration values from the database at the specified intervals.
• Manual Refresh: Call DatabaseConfigurationSource.Reload(); to manually trigger a configuration reload at any time.