Make validator lifetimes configurable on a validator-by-validator level

src/Carter/CarterConfigurator.cs

@@ -2,6 +2,7 @@ namespace Carter;
 
 using System;
 using System.Collections.Generic;
+using System.Reflection;
 using FluentValidation;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
@@ -16,16 +17,21 @@ internal CarterConfigurator()
         this.ModuleTypes = new List<Type>();
         this.ValidatorTypes = new List<Type>();
         this.ResponseNegotiatorTypes = new List<Type>();
-        this.ValidatorServiceLifetime = ServiceLifetime.Singleton;
+        this.DefaultValidatorServiceLifetime = ServiceLifetime.Singleton;
+        this.ValidatorServiceLifetimeFactory = (validatorType) =>
+            validatorType.GetCustomAttribute<ValidatorLifetimeAttribute>()?.Lifetime ??
+            this.DefaultValidatorServiceLifetime;
     }
 
     internal bool ExcludeValidators;
 
     internal bool ExcludeModules;
-        
+
     internal bool ExcludeResponseNegotiators;
 
-    internal ServiceLifetime ValidatorServiceLifetime;
+    internal ServiceLifetime DefaultValidatorServiceLifetime;
+
+    internal Func<Type, ServiceLifetime> ValidatorServiceLifetimeFactory;
 
     internal List<Type> ModuleTypes { get; }
 
@@ -131,7 +137,7 @@ public CarterConfigurator WithEmptyValidators()
         this.ExcludeValidators = true;
         return this;
     }
-        
+
     /// <summary>
     /// Do not register any modules
     /// </summary>
@@ -141,7 +147,7 @@ public CarterConfigurator WithEmptyModules()
         this.ExcludeModules = true;
         return this;
     }
-        
+
     /// <summary>
     /// Do not register any response negotiators
     /// </summary>
@@ -153,13 +159,24 @@ public CarterConfigurator WithEmptyResponseNegotiators()
     }
 
     /// <summary>
-    /// Define the lifetime of the validator
+    /// Define the default lifetime of the validator
     /// Default: Singleton
     /// </summary>
     /// <returns></returns>
-    public CarterConfigurator WithValidatorLifetime(ServiceLifetime serviceLifetime)
+    public CarterConfigurator WithDefaultValidatorLifetime(ServiceLifetime serviceLifetime)
+    {
+        this.DefaultValidatorServiceLifetime = serviceLifetime;
+        this.ValidatorServiceLifetimeFactory = (_) => serviceLifetime;
+        return this;
+    }
+
+    /// <summary>
+    /// Define the validator lifetime factory for custom validator lifetimes based on their type
+    /// </summary>
+    public CarterConfigurator WithValidatorServiceLifetimeFactory(
+        Func<Type, ServiceLifetime> validatorServiceLifetimeFactory)
     {
-        this.ValidatorServiceLifetime = serviceLifetime;
+        this.ValidatorServiceLifetimeFactory = validatorServiceLifetimeFactory;
         return this;
     }
 }

src/Carter/CarterExtensions.cs

@@ -30,7 +30,7 @@
 
         foreach (var carterModuleInterface in builder.ServiceProvider.GetServices<ICarterModule>())
         {
             if (carterModuleInterface is CarterModule carterModule)
             {
                 var group = builder.MapGroup(carterModule.basePath);
 
@@ -175,26 +175,33 @@
 
         services.AddSingleton(carterConfigurator);
 
+        ServiceLifetime validatorLocatorLifetime = ServiceLifetime.Singleton;
         foreach (var validator in validators)
         {
+            var validatorServiceLifetime = carterConfigurator.ValidatorServiceLifetimeFactory(validator);
             services.Add(
                 new ServiceDescriptor(
                     serviceType: typeof(IValidator),
                     implementationType: validator,
-                    lifetime: carterConfigurator.ValidatorServiceLifetime));
+                    lifetime: validatorServiceLifetime));
 
             services.Add(
                 new ServiceDescriptor(
                     serviceType: validator,
                     implementationType: validator,
-                    lifetime: carterConfigurator.ValidatorServiceLifetime));
+                    lifetime: validatorServiceLifetime));
+
+            if (validatorServiceLifetime < validatorLocatorLifetime)
+            {
+                validatorLocatorLifetime = validatorServiceLifetime;
+            }
         }
 
         services.Add(
             new ServiceDescriptor(
                 serviceType: typeof(IValidatorLocator),
                 implementationType: typeof(DefaultValidatorLocator),
-                lifetime: carterConfigurator.ValidatorServiceLifetime));
+                lifetime: validatorLocatorLifetime));
 
         foreach (var newModule in newModules)
         {

src/Carter/ValidatorLifetimeAttirubute.cs

@@ -0,0 +1,10 @@
+namespace Carter;
+
+using System;
+using Microsoft.Extensions.DependencyInjection;
+
+[AttributeUsage(AttributeTargets.Class)]
+public sealed class ValidatorLifetimeAttribute(ServiceLifetime lifetime) : Attribute
+{
+    public ServiceLifetime Lifetime { get; } = lifetime;
+}