/// <summary>
/// Converts the most recently added configuration source into a read-only configuration source.
/// </summary>
/// <param name="builder">The configuration builder.</param>
/// <returns>The configuration builder.</returns>
/// <remarks>
/// <para>
/// This method is intended to be chained after each source that needs to be made read-only.
/// </para>
///
/// <code>
/// IConfiguration configuration = new ConfigurationBuilder()
/// .AddInMemoryCollection(defaultSettings).AsReadOnly()
/// .AddIniFile("usersettings.ini").AsReadOnly()
/// .AddSQLite()
/// .Build();
///
/// // This will only update the SQLite configuration provider
/// configuration["Hello"] = "World";
/// </code>
/// </remarks>
/// <seealso cref="ReadOnlyConfigurationSource"/>
public static IConfigurationBuilder AsReadOnly(this IConfigurationBuilder builder)
{
int index = builder.Sources.Count - 1;
IConfigurationSource source = builder.Sources[index];
IConfigurationSource readOnlySource = new ReadOnlyConfigurationSource(source);
builder.Sources[index] = readOnlySource;
return(builder);
}
/// <summary>
/// Configures an <see cref="IConfigurationBuilder"/> with read-only configuration sources.
/// </summary>
/// <param name="builder">The configuration builder.</param>
/// <param name="builderAction">The action to set up configuration sources that will be made read-only.</param>
/// <returns>The configuration builder.</returns>
/// <remarks>
/// <para>
/// This method is intended to encapsulate the builder action that creates a group of read-only providers.
/// </para>
///
/// <code>
/// IConfiguration configuration = new ConfigurationBuilder()
/// .ConfigureReadOnly(readOnlyBuilder => readOnlyBuilder
/// .AddInMemoryCollection(defaultSettings)
/// .AddIniFile("usersettings.ini"))
/// .AddSQLite()
/// .Build();
///
/// // This will only update the SQLite configuration provider
/// configuration["Hello"] = "World";
/// </code>
/// </remarks>
public static IConfigurationBuilder ConfigureReadOnly(this IConfigurationBuilder builder, Action <IConfigurationBuilder> builderAction)
{
ReferenceEqualityComparer referenceEqualityComparer = new ReferenceEqualityComparer();
HashSet <object> originalSources = new HashSet <object>(builder.Sources, referenceEqualityComparer);
builderAction(builder);
for (int i = 0; i < builder.Sources.Count; i++)
{
IConfigurationSource source = builder.Sources[i];
if (originalSources.Contains(source))
{
continue;
}
IConfigurationSource readOnlySource = new ReadOnlyConfigurationSource(source);
builder.Sources[i] = readOnlySource;
}
return(builder);
}