Added feature: Deferred props

Author: mergehez

InertiaNetCore/Inertia.cs

@@ -38,6 +38,9 @@ public static class Inertia
 
     public static LazyProp<T> Lazy<T>(Func<T?> callback) => _factory.Lazy(callback);
     public static LazyProp<T> Lazy<T>(Func<Task<T?>> callback) => _factory.Lazy(callback);
+
+    public static DeferredProp<T> Defer<T>(Func<T?> callback, string? group = null) => _factory.Defer(callback, group);
+    public static DeferredProp<T> Defer<T>(Func<Task<T?>> callback, string? group = null) => _factory.Defer(callback, group);
 
     public static AlwaysProp<T> Always<T>(Func<T?> callback) => _factory.Always(callback);
     public static AlwaysProp<T> Always<T>(Func<Task<T?>> callback) => _factory.Always(callback);

InertiaNetCore/Models/InertiaPage.cs

@@ -1,9 +1,10 @@
 namespace InertiaNetCore.Models;
 
-public readonly record struct InertiaPage()
+public readonly record struct InertiaPage
 {
-    public InertiaProps Props { get; init; } = default!;
-    public string Component { get; init; } = default!;
-    public string? Version { get; init; } = null;
-    public string Url { get; init; } = default!;
+    public required InertiaProps Props { get; init; }
+    public required Dictionary<string, List<string>> DeferredProps { get; init; }
+    public required string Component { get; init; }
+    public required string? Version { get; init; }
+    public required string Url { get; init; }
 }

InertiaNetCore/Models/InertiaProps.cs

@@ -13,7 +13,7 @@ internal async Task<InertiaProps> ToProcessedProps(List<string>? partials)
 
         foreach (var (key, value) in this)
         {
-            if(partials is null && value is ILazyProp)
+            if(partials is null && value is IIgnoreFirstProp)
                 continue;
 
             if(partials is not null && value is not IAlwaysProp && !partials.Contains(key, StringComparer.InvariantCultureIgnoreCase))

InertiaNetCore/Response.cs

@@ -1,6 +1,7 @@
 using System.Text.Json;
 using InertiaNetCore.Extensions;
 using InertiaNetCore.Models;
+using InertiaNetCore.Utils;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
@@ -21,6 +22,7 @@ public async Task ExecuteResultAsync(ActionContext context)
             Version = version,
             Url = context.HttpContext.RequestedUri(),
             Props = await GetFinalProps(context),
+            DeferredProps = GetDeferredProps(context),
         };
 
         if (!context.HttpContext.IsInertiaRequest())
@@ -70,6 +72,20 @@ private async Task<InertiaProps> GetFinalProps(ActionContext context)
         return finalProps;
     }
 
+    private Dictionary<string, List<string>> GetDeferredProps(ActionContext context)
+    {
+        if (context.IsInertiaPartialComponent(component))
+            return [];
+
+        return props
+            .Where(prop => prop.Value is IDeferredProp)
+            .GroupBy(prop => (prop.Value as IDeferredProp)!.Group)
+            .ToDictionary(
+                g => g.Key ?? g.Select(x => x.Key).First(),
+                g => g.Select(x => x.Key).ToList()
+                );
+    }
+    
     private static Dictionary<string, string> GetErrors(ActionContext context)
     {
         var sessionErrors = context.HttpContext.Session.GetString("errors");

InertiaNetCore/ResponseFactory.cs

@@ -113,6 +113,8 @@ public void Flash(string key, string? value)
 
     public LazyProp<T> Lazy<T>(Func<T?> callback) => new(callback);
     public LazyProp<T> Lazy<T>(Func<Task<T?>> callback) => new(callback);
+    public DeferredProp<T> Defer<T>(Func<T?> callback, string? group) => new(callback, group);
+    public DeferredProp<T> Defer<T>(Func<Task<T?>> callback, string? group) => new(callback, group);
     public AlwaysProp<T> Always<T>(Func<T?> callback) => new(callback);
     public AlwaysProp<T> Always<T>(Func<Task<T?>> callback) => new(callback);
 }

InertiaNetCore/Utils/DeferProp.cs

@@ -0,0 +1,20 @@
+namespace InertiaNetCore.Utils;
+
+/// <summary>
+/// Deferred props allow you to defer the loading of certain page data until after the initial page render.
+/// This can be useful for improving the perceived performance of your app by allowing the initial page render to happen as quickly as possible.
+/// </summary>
+public class DeferredProp<T> : InvokableProp<T>, IDeferredProp
+{
+    public string? Group { get; }
+
+    public DeferredProp(Func<T?> callback, string? group) : base(callback)
+    {
+        Group = group;
+    }
+
+    public DeferredProp(Func<Task<T?>> callbackAsync, string? group) : base(callbackAsync)
+    {
+        Group = group;
+    }
+}

InertiaNetCore/Utils/Interfaces.cs

@@ -2,18 +2,24 @@
 
 namespace InertiaNetCore.Utils;
 
+public interface IViteBuilder
+{
+    HtmlString ReactRefresh();
+    HtmlString Input(string path);
+}
+
 internal interface IInvokableProp
 {
     internal Task<object?> InvokeToObject();
 }
 
 internal interface IAlwaysProp;
 
-internal interface ILazyProp;
+internal interface IIgnoreFirstProp;
 
+internal interface ILazyProp : IIgnoreFirstProp;
 
-public interface IViteBuilder
+internal interface IDeferredProp : IIgnoreFirstProp
 {
-    HtmlString ReactRefresh();
-    HtmlString Input(string path);
+    string? Group { get; }
 }

README.md

@@ -333,6 +333,6 @@ export default defineConfig({
 
 ## Work in progress
 
-- [ ] Deferred props
+- [x] Deferred props
 - [ ] Merging props
 - [ ] History encryption