ioptions-validation-minivalidation

Author: andrewlock

ioptions-validation-minivalidation/IOptionsValidationMiniValidation.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="MiniValidation" Version="0.7.4" />
+  </ItemGroup>
+
+</Project>

ioptions-validation-minivalidation/Program.cs

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+using System.ComponentModel.DataAnnotations;
+using Microsoft.Extensions.Options;
+using MiniValidation;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddOptions<MySettings>()
+    .BindConfiguration("MySettings")
+    .ValidateMiniValidation() // <- Enable validation
+    .ValidateOnStart(); // <- Validate on app start
+
+// Explicitly register the settings object by delegating to the IOptions object
+builder.Services.AddSingleton(resolver => 
+        resolver.GetRequiredService<IOptions<MySettings>>().Value);
+
+var app = builder.Build();
+
+// app.MapGet("/", (IOptions<MySettings> options) => options.Value);
+app.MapGet("/", (MySettings options) => options);
+
+app.Run();
+
+public class MySettings
+{
+    [Required]
+    public string DisplayName { get; set; }
+
+    [Required]
+    public NestedSettings Nested { get; set; }
+
+    public class NestedSettings
+    {
+        [Required]
+        public string Value { get; set; }
+
+        [Range(1, 100)]
+        public int Count { get; set; }
+    }
+}
+
+public static class MiniValidationExtensions
+{
+    public static OptionsBuilder<TOptions> ValidateMiniValidation<TOptions>(
+        this OptionsBuilder<TOptions> optionsBuilder) where TOptions : class
+    {
+        optionsBuilder.Services.AddSingleton<IValidateOptions<TOptions>>(
+            new MiniValidationValidateOptions<TOptions>(optionsBuilder.Name));
+        return optionsBuilder;
+    }
+}
+
+    public class MiniValidationValidateOptions<TOptions>
+        : IValidateOptions<TOptions> where TOptions : class
+    {
+        public MiniValidationValidateOptions(string? name)
+        {
+            Name = name;
+        }
+
+        public string? Name { get; }
+
+        public ValidateOptionsResult Validate(string? name, TOptions options)
+        {
+            // Null name is used to configure all named options.
+            if (Name != null && Name != name)
+            {
+                // Ignored if not validating this instance.
+                return ValidateOptionsResult.Skip;
+            }
+
+            // Ensure options are provided to validate against
+            ArgumentNullException.ThrowIfNull(options);
+
+            if (MiniValidator.TryValidate(options, out var validationErrors))
+            {
+                return ValidateOptionsResult.Success;
+            }
+
+            var typeName = options.GetType().Name;
+            var errors = new List<string>();
+            foreach (var (member, memberErrors) in validationErrors)
+            {
+                errors.Add($"DataAnnotation validation failed for '{typeName}' member: '{member}' with errors: '{string.Join("', '", memberErrors)}'.");
+            }
+
+            return ValidateOptionsResult.Fail(errors);
+        }
+    }

ioptions-validation-minivalidation/Properties/launchSettings.json

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+{
+  "iisSettings": {
+    "windowsAuthentication": false,
+    "anonymousAuthentication": true,
+    "iisExpress": {
+      "applicationUrl": "http://localhost:27028",
+      "sslPort": 44379
+    }
+  },
+  "profiles": {
+    "StronglyTypedValidation": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "https://localhost:7282;http://localhost:5101",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "IIS Express": {
+      "commandName": "IISExpress",
+      "launchBrowser": true,
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

ioptions-validation-minivalidation/appsettings.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*",
+  "MySettings": {
+    "DisplayName": "Display",
+    "Nested" : {
+      "Count": 0
+    }
+  }
+}