(#2) Add a provider

Author: colinangusmackay

src/SQL Scripts/CreateAppConfigurationTable.sql

@@ -0,0 +1,10 @@
+-- Run this in to your database. You can change the schema to suit if you need to.
+
+CREATE SCHEMA Stravaig;
+GO
+CREATE TABLE Stravaig.AppConfiguation
+(
+    ConfigKey NVARCHAR(1024) PRIMARY KEY CLUSTERED,
+    ConfigValue NVARCHAR(MAX)
+);
+GO

src/Stravaig.Configuration.SqlServer.Tests/FakeDataLoader.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+
+namespace Stravaig.Configuration.SqlServer.Tests;
+
+public class FakeDataLoader : IDataLoader
+{
+    public KeyValuePair<string, string>[] FakeData { get; set; } = Array.Empty<KeyValuePair<string, string>>();
+    public IEnumerable<KeyValuePair<string, string>> RetrieveData(SqlServerConfigurationSource source)
+    {
+        return FakeData;
+    }
+}

src/Stravaig.Configuration.SqlServer.Tests/Stravaig.Configuration.SqlServer.Tests.csproj

@@ -7,11 +7,16 @@
     </PropertyGroup>
 
     <ItemGroup>
+        <PackageReference Include="Microsoft.Extensions.Hosting" Version="6.0.0" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.0.0"/>
         <PackageReference Include="NUnit" Version="3.13.2"/>
         <PackageReference Include="NUnit3TestAdapter" Version="4.2.1"/>
         <PackageReference Include="coverlet.collector" Version="3.1.1"/>
         <PackageReference Include="Shouldly" Version="4.0.3"/>
     </ItemGroup>
 
+    <ItemGroup>
+      <ProjectReference Include="..\Stravaig.Configuration.SqlServer\Stravaig.Configuration.SqlServer.csproj" />
+    </ItemGroup>
+
 </Project>

src/Stravaig.Configuration.SqlServer.Tests/UnitTest1.cs

@@ -1,17 +1,51 @@
+using System.Collections.Generic;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Hosting;
 using NUnit.Framework;
+using Shouldly;
 
 namespace Stravaig.Configuration.SqlServer.Tests;
 
-public class Tests
+public class SqlServerConfigurationProviderTests
 {
+    private const string DummyConnectionString = "Server=localhost;Database=testing";
+
     [SetUp]
     public void Setup()
     {
+
     }
 
     [Test]
-    public void Test1()
+    public void ValuesAreRetrievable()
     {
-        Assert.Pass();
+        var provider = SetupProvider();
+        provider.Load();
+
+        provider.TryGet("A", out var value);
+        value.ShouldBe("111");
+        
+        provider.TryGet("B:A", out value);
+        value.ShouldBe("222");
+
+        provider.TryGet("B:B", out value);
+        value.ShouldBe("333");
+    }
+    
+    private static SqlServerConfigurationProvider SetupProvider()
+    {
+        var fakeDataLoader = new FakeDataLoader()
+        {
+            FakeData = new[]
+            {
+                new KeyValuePair<string, string>("A", "111"),
+                new KeyValuePair<string, string>("B:A", "222"),
+                new KeyValuePair<string, string>("B:B", "333"),
+            }
+        };
+
+        var provider =
+            new SqlServerConfigurationProvider(new SqlServerConfigurationSource(DummyConnectionString), fakeDataLoader);
+        return provider;
     }
 }

src/Stravaig.Configuration.SqlServer/AssemblyInfo.cs

@@ -0,0 +1,3 @@
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Stravaig.Configuration.SqlServer.Tests")]

src/Stravaig.Configuration.SqlServer/Class1.cs

@@ -0,0 +1,33 @@
+using System.Collections.Generic;
+using System.Data.SqlClient;
+
+namespace Stravaig.Configuration.SqlServer;
+
+public interface IDataLoader
+{
+    IEnumerable<KeyValuePair<string, string>> RetrieveData(SqlServerConfigurationSource source);
+}
+public class DataLoader : IDataLoader
+{
+    private const string RetrieveSqlTemplate = "SELECT [ConfigKey], [ConfigValue] FROM [{0}].[{1}]";
+    private const int keyColumnPosition = 0;
+    private const int valueColumnPosition = 1;
+
+    public IEnumerable<KeyValuePair<string, string>> RetrieveData(SqlServerConfigurationSource source)
+    {
+        var sql = RetrieveSql(source.SchemaName, source.TableName);
+        using SqlConnection connection = new SqlConnection(source.ConnectionString);
+        connection.Open();
+        var cmd = new SqlCommand(sql, connection);
+        using var reader = cmd.ExecuteReader();
+        while (reader.HasRows)
+        {
+            var key = reader.GetString(keyColumnPosition);
+            var value = reader.GetString(valueColumnPosition);
+            yield return new KeyValuePair<string, string>(key, value);
+        }
+    }
+
+    private string RetrieveSql(string schemaName, string tableName) =>
+        string.Format(RetrieveSqlTemplate, schemaName, tableName);
+}

src/Stravaig.Configuration.SqlServer/DataLoader.cs

@@ -0,0 +1,27 @@
+using System;
+using Microsoft.Extensions.Configuration;
+
+namespace Stravaig.Configuration.SqlServer;
+
+public static class SqlServerConfigurationBuilderExtensions
+{
+    public static IConfigurationBuilder AddSqlServer(this IConfigurationBuilder builder, Action<SqlServerConfigurationOptions>? optionsBuilder = null)
+    {
+        var options = new SqlServerConfigurationOptions();
+        optionsBuilder?.Invoke(options);
+
+        if (!string.IsNullOrWhiteSpace(options.ConfigurationSection))
+            SetOptionsFromConfiguration(builder.Build(), options);
+        
+        return builder.Add(new SqlServerConfigurationSource(
+            options.ConnectionString ?? throw new InvalidOperationException("Cannot build a SQL Server Configuration Provider with a null connection string."),
+            options.SchemaName,
+            options.TableName));
+    }
+
+    private static void SetOptionsFromConfiguration(IConfigurationRoot configRoot, SqlServerConfigurationOptions options)
+    {
+        var section = configRoot.GetSection(options.ConfigurationSection);
+        section.Bind(options);
+    }
+}

src/Stravaig.Configuration.SqlServer/SqlServerConfigurationBuilderExtensions.cs

@@ -0,0 +1,9 @@
+namespace Stravaig.Configuration.SqlServer;
+
+public class SqlServerConfigurationOptions
+{
+    public string? ConnectionString { get; set; }
+    public string? ConfigurationSection { get; set; }
+    public string SchemaName { get; set; } = "Stravaig";
+    public string TableName { get; set; } = "AppConfiguration";
+}

src/Stravaig.Configuration.SqlServer/SqlServerConfigurationOptions.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using Microsoft.Extensions.Configuration;
+
+namespace Stravaig.Configuration.SqlServer;
+
+public class SqlServerConfigurationProvider : ConfigurationProvider
+{
+    private readonly SqlServerConfigurationSource _source;
+    private readonly IDataLoader _dataLoader;
+
+    public SqlServerConfigurationProvider(SqlServerConfigurationSource source)
+        : this (source, new DataLoader())
+    {
+    }
+
+    internal SqlServerConfigurationProvider(SqlServerConfigurationSource source, IDataLoader dataLoader)
+    {
+        _source = source;
+        _dataLoader = dataLoader;
+    }
+    
+    public override void Load()
+    {
+        var data = _dataLoader.RetrieveData(_source);
+        Data = new Dictionary<string, string>(data, StringComparer.OrdinalIgnoreCase);
+    }
+}