Working implementation

RAIC.Extensions.Configuration.EntityFrameworkCore/README.md

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+# RAIC.Extensions.Configuration.EntityFrameworkCore
+
+This library is a `Microsoft.Extensions.Configuration.IConfigurationProvider` that reads settings from a `DbSet<ISetting> Settings` property 
+present on your Entity Framework Core `DbContext`.
+
+## Goals
+1. Usable with minimal constraints on your entity model
+1. Follows conventional configuration patterns 
+1. `IOptionsMonitor` update support through optional opt-in services (see `RAIC.Extensions.Configuration.EntityFrameworkCore.PostgreSQL` & `RAIC.Extensions.Configuration.EntityFrameworkCore.SqlServer`)
+
+
+## Requirements
+* .NET 8
+
+
+## Gotchas
+* Setting values cannot be `null` (as signified by the `RequiredAttribute` on `ISetting.Value`)
+* Setting keys should not contain the `=` character (similar to `CommandLineConfigurationProvider` & `EnvironmentVariablesConfigurationProvider`)
+
+
+## Usage Example
+
+```csharp
+
+using RAIC.Extensions.Configuration.EntityFrameworkCore.Extensions;
+
+public record Setting : ISetting
+{
+    [Key]
+    public required string Key { get; set; }
+
+    [Required]
+    public required string Value { get; set; }
+}
+
+public class MyDbContext(DbContextOptions<MyDbContext> options) : DbContext(options), ISettingsDbContext<DbSet<Setting>, Setting>
+{
+    public DbSet<Setting> Settings { get; set; }
+}
+
+var builder =  Host.CreateApplicationBuilder(args) // or  WebApplication.CreateBuilder(args); 
+
+// build an initial configuration
+builder.Configuration.AddJsonFile("appsettings.json")
+                     .AddUserSecrets<Program>(); // or whereever your connection string lives
+
+// obtain connection string from preliminary config so can initialise other settings from DbSet
+builder.Configuration.AddDbSet<MyDbContext, Setting>(dbContextOptions => dbContextOptions.UseNpgsql(builder.Configuration.GetConnectionString("Default")));
+
+...
+
+await builder.Build().RunAsync(); // use config as normal
+
+```
+
+Read more about [Configuration](https://docs.microsoft.com/en-us/dotnet/core/extensions/configuration) on the Microsoft Docs site.