How to access configuration provider values in asp.net core startup - asp.net-core

Question

In my asp.net core 3.1 project I have setup a custom sql provider which is working great. In my Startup I want to load only the values from the SQLConfigurationProvider into a separate dictionary for use throughout my app. I can see that the configuration object contains a collection of providers as per below screenshot. However I cannot find a way to access only the SQLConfigurationProvider and get the subsequent values. Is this possible?

Answer 1

What you can do is very simple. Once you build your ConfigurationRoot
IConfigurationRoot configRoot = config.Build();
What you can do is to enumerate to a List only the providers you want:
var providers = configRoot.Providers.Where(
p => (p.GetType().Name == "AzureAppConfigurationProvider") ||
(p.GetType().Name == "AzureKeyVaultConfigurationProvider")).ToList();
Then, recreate a new temporary ConfigurationRoot using only the selected providers:
var tempRoot = new ConfigurationRoot(new List<IConfigurationProvider>(providers));
Then, in order to get the values you can do the following:
tempRoot.AsEnumerable().ToDictionary(a => a.Key, a => a.Value)
This way you will get a Dictionary with the key/value pairs of the configuration.
Note: When you initialize a new ConfigurationRoot from the providers, the SDK triggers again the loading of the configuration which might introduce delays (especially if the configuration is retrieved from a cloud service). If you don't want something like that then you probably have to go with the solution suggested by Brando.

Answer 2

According to your description, I suggest you could firstly use Configuration.Providers to get the SQLConfigurationProvider.
But the ConfigurationProvider's data property is protected, so we should write a extension method to get the value and set it into a directory.
More details, you could refer to below codes:
Create a extension class:
public static class ConfigurationProviderExtensions
{
public static HashSet<string> GetFullKeyNames(this IConfigurationProvider provider, string rootKey, HashSet<string> initialKeys)
{
foreach (var key in provider.GetChildKeys(Enumerable.Empty<string>(), rootKey))
{
string surrogateKey = key;
if (rootKey != null)
{
surrogateKey = rootKey + ":" + key;
}
GetFullKeyNames(provider, surrogateKey, initialKeys);
if (!initialKeys.Any(k => k.StartsWith(surrogateKey)))
{
initialKeys.Add(surrogateKey);
}
}
return initialKeys;
}
}
Then you could add below codes to get the provider and get the value..
// Replace the EnvironmentVariablesConfigurationProvider to your provider
var re = ((ConfigurationRoot)Configuration).Providers.FirstOrDefault(x=>x.GetType() == typeof(EnvironmentVariablesConfigurationProvider));
var directory = new Dictionary<string, string>();
foreach (var key in re.GetFullKeyNames(null, new HashSet<string>()).OrderBy(p => p))
{
if (re.TryGet(key, out var value))
{
directory.Add(key, value);
}
}
Result: