AppConfig: Access the raw value of a feature flag setting

AppConfig-Policy.cs

// Package Reference: Azure.Data.AppConfiguration
// Package Reference: System.Text.Json
  
using Azure;
using Azure.Core;
using Azure.Core.Pipeline;
using Azure.Data.AppConfiguration;
using System.Threading.Tasks;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Net;
  
// Create the policy; this will be what we read the raw service values from.
    
var policy = new FeatureFlagPolicy();

// Create the client, using the policy by setting them in the options.

var options = new ConfigurationClientOptions();
options.AddPolicy(policy, HttpPipelinePosition.PerCall);
    
var client = new ConfigurationClient("<< CONNECTION STRING >>", options);
    
// Query the settings and output the client and service values for each.
    
var selector = new SettingSelector { LabelFilter = SettingSelector.Any };
var settings = client.GetConfigurationSettingsAsync(selector);
    
await foreach (var setting in settings)
{
    Console.WriteLine($@"
    {setting.Key}:
        Client Value:
            {setting.Value}
     
        Service Value: 
            {policy.RawValues[setting.Key]}
            
    ");
}

//
// This is the policy implementation responsible for intercepting the
// service response, parsing it, and exposing the raw valies/
//
public class FeatureFlagPolicy : HttpPipelineSynchronousPolicy
{
    public Dictionary<string, string> RawValues { get; } = new();

    public override void OnReceivedResponse(HttpMessage message)
    {
        base.OnReceivedResponse(message);

        // If there was no response or it was a failure, skip processing.

        if (message?.Response?.Status != (int)HttpStatusCode.OK)
        {
            return;
        }
        
        var serializerOptions = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
        var response = JsonSerializer.Deserialize<SettingsResponse>(message.Response.Content.ToString(), serializerOptions);

        // If the response couldn't be deserialized, skip processing.
        
        if (response == null)
        {
            return;
        }
        
        // Clear out the known values to avoid bloat; this will reset the cache
        // for each page of settings.

        RawValues.Clear();

        // Add the current raw value for settings to the cache.

        foreach (var setting in response.Items)
        {
            RawValues.Add(setting.Key, setting.Value);
        }
    }

    // Nested types just for serialization support.

    private class SettingsResponse
    {
        public MinimalSetting[] Items { get; set; }
    }

    private class MinimalSetting
    {
        [JsonPropertyName("content_type")]
        public string ContentType { get; set; }
        public string Key { get; set; }
        public string Value { get; set; }
    }
}