Demo IOptionsSnapshot, IOptionsMonitor, IOptions

Example3-IValidateOptions/src/Example3Api/Controllers/WeatherForecastController.cs

@@ -20,23 +20,38 @@ public class WeatherForecastController : ControllerBase
         private readonly ILogger<WeatherForecastController> _logger;
 
         private readonly DatabaseOptions _databaseOptions;
-        private UnvalidatedOptions _unvalidatedOptions;
+        private readonly UnvalidatedOptions _unvalidatedOptions;
+        private readonly MonitoredSettingsOptions _monitoredSettingsOptions;
+        private readonly UnmonitoredButValidatedOptions _unmonitoredButValidatedOptionsAccessor;
 
         public WeatherForecastController(
             ILogger<WeatherForecastController> logger,
             IOptionsSnapshot<DatabaseOptions> databaseOptionsAccessor,
-            IOptions<UnvalidatedOptions> unvalidatedOptionsAccessor
+            IOptions<UnvalidatedOptions> unvalidatedOptionsAccessor,
+            IOptionsMonitor<MonitoredSettingsOptions> monitoredSettingsOptionsAccessor,
+            IOptions<UnmonitoredButValidatedOptions> unmonitoredButValidatedOptionsAccessor
             )
         {
             _logger = logger;
 
-            _unvalidatedOptions = unvalidatedOptionsAccessor.Value;
-
-            /* if IOptions validation fails, code will error out here (first access)
+            /* If options-pattern validation fails, code will error out here.  However, it will error out on the
+             * first object that fails to validate.  You could wrap a try-catch around all of the calls.
+             * 
              * example:
              *   - OptionsValidationException: Comment1 is required.; DatabaseType is required.; Comment2 is required.;
              *     SchemaNames.Schema1 is required.; SchemaNames.Schema2 is required.
              */
+
+            // There's no validator for this one.
+            _unvalidatedOptions = unvalidatedOptionsAccessor.Value;
+
+            // IOptions<T> is a singleton that only validates on the first-use (anywhere).
+            _unmonitoredButValidatedOptionsAccessor = unmonitoredButValidatedOptionsAccessor.Value;
+
+            // IOptionsMonitor<T> only runs when the underlying file has actually changed (still a singleton).
+            _monitoredSettingsOptions = monitoredSettingsOptionsAccessor.CurrentValue;
+
+            // IOptionsSnapshot<T> runs validation on every new request.
             _databaseOptions = databaseOptionsAccessor.Value;
         }
 

Example3-IValidateOptions/src/Example3Api/Options/MonitoredSettingsOptions.cs

@@ -0,0 +1,11 @@
+using Example3Api.Attributes;
+
+namespace Example3Api.Options
+{
+    [ConfigurationSectionName("MonitoredSettings")]
+    public class MonitoredSettingsOptions
+    {
+        public string MonitorA { get; set; }
+        public string MonitorB { get; set; }
+    }
+}

Example3-IValidateOptions/src/Example3Api/Options/UnmonitoredButValidatedOptions.cs

@@ -0,0 +1,12 @@
+using Example3Api.Attributes;
+
+namespace Example3Api.Options
+{
+    [ConfigurationSectionName("UnmonitoredButValidated")]
+    public class UnmonitoredButValidatedOptions
+    {
+        public string OptionA { get; set; }
+        public string OptionB { get; set; }
+        public string OptionC { get; set; }
+    }
+}

Example3-IValidateOptions/src/Example3Api/OptionsValidators/MonitoredSettingsOptionsValidator.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using Example3Api.Attributes;
+using Example3Api.Options;
+using Microsoft.Extensions.Options;
+
+namespace Example3Api.OptionsValidators
+{
+    public class MonitoredSettingsOptionsValidator : IValidateOptions<MonitoredSettingsOptions>
+    {
+        public ValidateOptionsResult Validate(
+            string name, 
+            MonitoredSettingsOptions options
+            )
+        {
+            var sectionName = typeof(MonitoredSettingsOptions).GetCustomAttribute<ConfigurationSectionNameAttribute>()?.SectionName
+                ?? throw new ArgumentNullException(nameof(ConfigurationSectionNameAttribute));  
+
+            if (options is null)
+                return ValidateOptionsResult.Fail($"Configuration object is null for section '{sectionName}'.");
+
+            var failureMessages = new List<string>();
+
+            if (string.IsNullOrWhiteSpace(options.MonitorA))
+                failureMessages.Add($"{sectionName}.{nameof(options.MonitorA)} is required.");
+
+            if (string.IsNullOrWhiteSpace(options.MonitorB))
+                failureMessages.Add($"{sectionName}.{nameof(options.MonitorB)} is required.");
+
+            return failureMessages.Any()
+                ? ValidateOptionsResult.Fail(failureMessages)
+                : ValidateOptionsResult.Success;
+        }
+    }
+}

Example3-IValidateOptions/src/Example3Api/OptionsValidators/UnmonitoredButValidatedOptionsValidator.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using Example3Api.Attributes;
+using Example3Api.Options;
+using Microsoft.Extensions.Options;
+
+namespace Example3Api.OptionsValidators
+{
+    public class UnmonitoredButValidatedOptionsValidator : IValidateOptions<UnmonitoredButValidatedOptions>
+    {
+        public ValidateOptionsResult Validate(
+            string name, 
+            UnmonitoredButValidatedOptions options
+            )
+        {
+            var sectionName = typeof(UnmonitoredButValidatedOptions).GetCustomAttribute<ConfigurationSectionNameAttribute>()?.SectionName
+                ?? throw new ArgumentNullException(nameof(ConfigurationSectionNameAttribute));  
+
+            if (options is null)
+                return ValidateOptionsResult.Fail($"Configuration object is null for section '{sectionName}'.");
+
+            var failureMessages = new List<string>();
+
+            if (string.IsNullOrWhiteSpace(options.OptionA))
+                failureMessages.Add($"{sectionName}.{nameof(options.OptionA)} is required.");
+
+            if (string.IsNullOrWhiteSpace(options.OptionB))
+                failureMessages.Add($"{sectionName}.{nameof(options.OptionB)} is required.");
+
+            if (string.IsNullOrWhiteSpace(options.OptionC))
+                failureMessages.Add($"{sectionName}.{nameof(options.OptionC)} is required.");
+
+            return failureMessages.Any()
+                ? ValidateOptionsResult.Fail(failureMessages)
+                : ValidateOptionsResult.Success;
+        }
+    }
+}

Example3-IValidateOptions/src/Example3Api/Startup.cs

@@ -23,6 +23,8 @@ public void ConfigureServices(IServiceCollection services)
         {
             services.ConfigureAndValidateSection<DatabaseOptions, DatabaseOptionsValidator>(_configuration);
             services.ConfigureAndValidateSection<ConnectionStringsOptions, ConnectionStringsOptionsValidator>(_configuration);
+            services.ConfigureAndValidateSection<MonitoredSettingsOptions, MonitoredSettingsOptionsValidator>(_configuration);
+            services.ConfigureAndValidateSection<UnmonitoredButValidatedOptions, UnmonitoredButValidatedOptionsValidator>(_configuration);
             services.ConfigureSection<UnvalidatedOptions>(_configuration);
 
             services.AddControllers();

Example3-IValidateOptions/src/Example3Api/appsettings.json

@@ -7,10 +7,19 @@
     }
   },
   "AllowedHosts": "*",
+  "UnmonitoredButValidated": {
+    "OptionA": "Apple",
+    "OptionB": "Peach",
+    "OptionC": "Panda"
+  },
   "Unvalidated": {
     "ParameterA": null,
     "ParameterB": "Chekov"
   },
+  "MonitoredSettings": {
+    "MonitorA": "Francis",
+    "MonitorB": "Frannie"
+  },  
   "Database": {
     "Comment1": null,
     "DatabaseType": "Charlie",