186 lines
4.8 KiB
Markdown
186 lines
4.8 KiB
Markdown
# Skeleton
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An animated loading placeholder. Use it in place of real content while data is being fetched or rendered asynchronously. The animation communicates to the user that content is loading.
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---
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## HTML structure
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```
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div.animate-pulse.rounded-md.bg-muted.{classes}
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```
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---
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## CSS mechanics
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| Class | Effect |
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|---|---|
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| `animate-pulse` | Tailwind's built-in fade-in/out animation (1.5s loop) |
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| `bg-muted` | Neutral muted background color from the theme |
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| `rounded-md` | Slightly rounded corners |
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| User-supplied `classes` | Control size and shape (e.g. `h-4 w-32`, `h-10 w-full`, `rounded-full h-12 w-12`) |
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---
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## Constructor signature
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```csharp
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public Skeleton(string classes = "")
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```
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| Parameter | Description |
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| `classes` | Tailwind classes controlling size, shape, and spacing |
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---
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## Usage examples
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### Text line placeholders
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```csharp
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new Skeleton("h-4 w-3/4 mb-2")
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new Skeleton("h-4 w-1/2")
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```
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### Avatar placeholder
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```csharp
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new Skeleton("rounded-full h-12 w-12")
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```
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### Card skeleton loader
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```csharp
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new Card(
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content: """
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<div class="flex items-center gap-4">
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<!-- Render each Skeleton eagerly to a string or use slot injection -->
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</div>
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<div class="mt-4 space-y-2">
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</div>
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""")
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```
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### Full-width block placeholder
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```csharp
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new Skeleton("h-10 w-full")
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```
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### HTMX skeleton swap pattern
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```html
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<!-- Shown immediately; HTMX replaces with real content -->
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<div id="user-list"
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hx-get="/users"
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hx-trigger="load"
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hx-swap="outerHTML">
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$$UserListSkeleton$$
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</div>
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```
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The page renders the skeleton on initial load; the HTMX request fires immediately and replaces it once the data arrives.
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---
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## Tips and tricks
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- Multiple `Skeleton` elements stacked in a `div.space-y-2` create a convincing text-block placeholder.
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- `rounded-full` makes a circle — useful for avatar skeletons. Combine with equal `h-*` and `w-*` values.
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- The `classes` parameter replaces the default empty string — provide complete size + spacing classes.
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- For table skeletons, render a `Table` with each cell containing a Skeleton HTML string (pre-rendered to a string via `ArrayBufferWriter<byte>`).
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- Do not use Skeleton for truly empty states (no data to show) — use an `Alert` or empty-state illustration instead.
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- Do not use Skeleton for truly empty states (no data to show) — use an `Alert` or empty-state illustration instead.
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---
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## Complete page example
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**`Templates/UserListPage.htmx`**
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```html
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<div class="max-w-3xl mx-auto py-10">
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<h1 class="text-2xl font-bold mb-6">Users</h1>
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<div id="user-list"
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hx-get="/users/data"
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hx-trigger="load"
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hx-swap="outerHTML">
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$$LoadingSkeleton$$
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</div>
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</div>
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```
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**`Templates/UserListPage.htmx.cs`**
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```csharp
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namespace Htmx.ApiDemo.Templates;
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public sealed class UserListPage : UserListPageBase
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{
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private readonly byte[] _skeleton;
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public UserListPage()
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{
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// Build a table-shaped skeleton: 5 rows × 3 columns
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var row = new System.Text.StringBuilder();
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for (int i = 0; i < 5; i++)
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{
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row.Append("""<div class="flex gap-4 py-3 border-b">""");
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row.Append(SkeletonHtml("h-4 w-1/3"));
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row.Append(SkeletonHtml("h-4 w-1/4"));
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row.Append(SkeletonHtml("h-4 w-1/5"));
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row.Append("</div>");
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}
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_skeleton = row.ToString().ToUtf8Bytes();
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}
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private static string SkeletonHtml(string classes)
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{
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var buf = new System.Buffers.ArrayBufferWriter<byte>();
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new Components.Skeleton(classes).Render(new HtmxRenderContext(buf));
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return System.Text.Encoding.UTF8.GetString(buf.WrittenSpan);
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}
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protected override void RenderLoadingSkeleton(HtmxRenderContext ctx)
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=> ctx.Writer.WriteUtf8(_skeleton);
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}
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```
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**GET handlers**
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```csharp
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// Shell page — renders immediately with skeleton placeholder
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[Handler]
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[MapGet("/users")]
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public static partial class GetUsersShellHandler
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{
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public record Query();
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private static Task<IResult> HandleAsync(Query _, HttpContext ctx, CancellationToken ct)
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=> ctx.WriteHtmxPage(new UserListPage(), title: "Users");
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}
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// Data endpoint — HTMX swaps this in place of the skeleton
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[Handler]
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[MapGet("/users/data")]
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public static partial class GetUsersDataHandler
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{
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public record Query();
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private static async Task<IResult> HandleAsync(
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Query _, HttpContext ctx, MongoDbService db, CancellationToken ct)
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{
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var users = await db.GetAllUsersAsync(ct);
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var table = new Components.Table(
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headers: new[] { "Name", "Email", "Role" },
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rows: users.Select(u => new[]
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{
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System.Net.WebUtility.HtmlEncode(u.DisplayName ?? ""),
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System.Net.WebUtility.HtmlEncode(u.Email),
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"user",
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}));
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var buf = new System.Buffers.ArrayBufferWriter<byte>();
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table.Render(new HtmxRenderContext(buf));
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return Results.Content(
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System.Text.Encoding.UTF8.GetString(buf.WrittenSpan), "text/html");
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}
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}
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```
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