Input Large Text Area

src/InputLargeTextArea/InputLargeTextArea.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.0.31612.314
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "InputLargeTextArea", "src\InputLargeTextArea\InputLargeTextArea.csproj", "{D3C10569-1320-4C66-B76B-FC02BDC9010F}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SampleServerApp", "SampleServerApp\SampleServerApp.csproj", "{8162C3A5-8054-4647-B597-64A01027EC24}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{D3C10569-1320-4C66-B76B-FC02BDC9010F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D3C10569-1320-4C66-B76B-FC02BDC9010F}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D3C10569-1320-4C66-B76B-FC02BDC9010F}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D3C10569-1320-4C66-B76B-FC02BDC9010F}.Release|Any CPU.Build.0 = Release|Any CPU
+		{8162C3A5-8054-4647-B597-64A01027EC24}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8162C3A5-8054-4647-B597-64A01027EC24}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8162C3A5-8054-4647-B597-64A01027EC24}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8162C3A5-8054-4647-B597-64A01027EC24}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {130EF2A6-BAD0-430B-9B31-D35406A46F67}
+	EndGlobalSection
+EndGlobal

src/InputLargeTextArea/README.md

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+## Blazor `InputLargeTextArea` Component Sample
+A multiline input component for Blazor Server to enable editing large string values. Supports async content access without binding and without validations.
+
+### Example:
+```csharp
+<InputLargeTextArea id="largeTextArea" @ref="TextArea" OnChange="TextAreaChanged" />
+
+
+@code {
+  InputLargeTextArea? TextArea;
+
+  public async Task GetTextAsync()
+  {
+      var streamReader = await TextArea!.GetTextAsync(maxLength: 50_000);
+      var textFromInputLargeTextArea = await streamReader.ReadToEndAsync();
+  }
+
+  public async Task SetTextAsync()
+  {
+      var textToWrite = new string('c', 50_000);
+
+      var memoryStream = new MemoryStream();
+      var streamWriter = new StreamWriter(memoryStream);
+      await streamWriter.WriteAsync(textToWrite);
+      await streamWriter.FlushAsync();
+      await TextArea!.SetTextAsync(streamWriter);
+  }
+
+  public void TextAreaChanged(InputLargeTextAreaChangeEventArgs args)
+  {
+      LastChangedLength = args.Length;
+  }
+}
+```
+
+## Why?
+Using Blazor Server's `InputTextArea` with large (ex. 20K chars) amounts of text can lead to a degraded user experience due to the constant round-trip communication to/from the server to enable binding and validations. This component provides an asynchronous ability to get & set the text area content. This approach **is not optimal** due to the additional complexity working with `StreamReader`/`StreamWriter` APIs, as well as the (large) amount of memory allocations which may occur when encoding/decoding the `UTF-8` `string`/`textarea` content into `byte`s. Due to these concerns, we've made this available as a sample instead of adding it to the core framework.
+
+Note: If you're encountering slowdowns specifically in complex components or Blazor WebAssembly, we recommend reviewing the [Blazor WebAssembly Performance Best Practices](https://docs.microsoft.com/en-us/aspnet/core/blazor/webassembly-performance-best-practices?view=aspnetcore-6.0#avoid-rerendering-after-handling-events-without-state-changes) which detail rendering optimizations.
+
+## Setup
+1. Add a package reference to `InputLargeTextArea`.
+2. Add `<script src="_content/InputLargeTextArea/js/InputLargeTextArea.js"></script>` to your `_Layout.cshtml` on Blazor Server.

src/InputLargeTextArea/SampleServerApp/App.razor

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+<Router AppAssembly="@typeof(App).Assembly">
+    <Found Context="routeData">
+        <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
+        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
+    </Found>
+    <NotFound>
+        <PageTitle>Not found</PageTitle>
+        <LayoutView Layout="@typeof(MainLayout)">
+            <p role="alert">Sorry, there's nothing at this address.</p>
+        </LayoutView>
+    </NotFound>
+</Router>

src/InputLargeTextArea/SampleServerApp/Pages/Error.cshtml

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+@page
+@model SampleServerApp.Pages.ErrorModel
+
+<!DOCTYPE html>
+<html>
+
+<head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
+    <title>Error</title>
+    <link href="~/css/bootstrap/bootstrap.min.css" rel="stylesheet" />
+    <link href="~/css/site.css" rel="stylesheet" asp-append-version="true" />
+</head>
+
+<body>
+    <div class="main">
+        <div class="content px-4">
+            <h1 class="text-danger">Error.</h1>
+            <h2 class="text-danger">An error occurred while processing your request.</h2>
+
+            @if (Model.ShowRequestId)
+            {
+                <p>
+                    <strong>Request ID:</strong> <code>@Model.RequestId</code>
+                </p>
+            }
+
+            <h3>Development Mode</h3>
+            <p>
+                Swapping to the <strong>Development</strong> environment displays detailed information about the error that occurred.
+            </p>
+            <p>
+                <strong>The Development environment shouldn't be enabled for deployed applications.</strong>
+                It can result in displaying sensitive information from exceptions to end users.
+                For local debugging, enable the <strong>Development</strong> environment by setting the <strong>ASPNETCORE_ENVIRONMENT</strong> environment variable to <strong>Development</strong>
+                and restarting the app.
+            </p>
+        </div>
+    </div>
+</body>
+
+</html>

src/InputLargeTextArea/SampleServerApp/Pages/Error.cshtml.cs

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+using System.Diagnostics;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace SampleServerApp.Pages;
+
+[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
+[IgnoreAntiforgeryToken]
+public class ErrorModel : PageModel
+{
+    public string? RequestId { get; set; }
+
+    public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
+
+    private readonly ILogger<ErrorModel> _logger;
+
+    public ErrorModel(ILogger<ErrorModel> logger)
+    {
+        _logger = logger;
+    }
+
+    public void OnGet()
+    {
+        RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier;
+    }
+}

src/InputLargeTextArea/SampleServerApp/Pages/Index.razor

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+@page "/"
+@using Microsoft.AspNetCore.Components.Forms
+
+<PageTitle>Input Large Text Area</PageTitle>
+
+<InputLargeTextArea id="largeTextArea" @ref="TextArea" OnChange="TextAreaChanged" />
+
+<br />
+
+<button id="setTextBtn" @onclick="SetTextAsync">SetTextAsync</button>
+<button id="getTextBtn" @onclick="GetTextAsync">GetTextAsync</button>
+
+<hr />
+
+<h3>Last Changed:</h3>
+Length: <p id="lastChangedLength">@LastChangedLength</p>
+
+<h3>Get Text Result:</h3>
+<p id="getTextResult">@GetTextResult</p>
+<p id="getTextError">@GetTextError</p>
+
+
+@code {
+  public long LastChangedLength { get; set; }
+  public string GetTextResult { get; set; } = string.Empty;
+  public string GetTextError { get; set; } = string.Empty;
+
+  InputLargeTextArea? TextArea;
+
+  public async Task GetTextAsync()
+  {
+      var streamReader = await TextArea!.GetTextAsync(maxLength: 50_000);
+      GetTextResult = await streamReader.ReadToEndAsync();
+      StateHasChanged();
+  }
+
+  public async Task SetTextAsync()
+  {
+      var memoryStream = new MemoryStream();
+      var streamWriter = new StreamWriter(memoryStream);
+      await streamWriter.WriteAsync(new string('c', 50_000));
+      await streamWriter.FlushAsync();
+      await TextArea!.SetTextAsync(streamWriter);
+  }
+
+  public void TextAreaChanged(InputLargeTextAreaChangeEventArgs args)
+  {
+      LastChangedLength = args.Length;
+  }
+}

src/InputLargeTextArea/SampleServerApp/Pages/_Host.cshtml

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+@page "/"
+@namespace SampleServerApp.Pages
+@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
+@{
+    Layout = "_Layout";
+}
+
+<component type="typeof(App)" render-mode="ServerPrerendered" />

src/InputLargeTextArea/SampleServerApp/Pages/_Layout.cshtml

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+@using Microsoft.AspNetCore.Components.Web
+@namespace SampleServerApp.Pages
+@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
+
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <base href="~/" />
+    <link rel="stylesheet" href="css/bootstrap/bootstrap.min.css" />
+    <link href="css/site.css" rel="stylesheet" />
+    <link href="SampleServerApp.styles.css" rel="stylesheet" />
+    <component type="typeof(HeadOutlet)" render-mode="ServerPrerendered" />
+</head>
+<body>
+    @RenderBody()
+
+    <div id="blazor-error-ui">
+        <environment include="Staging,Production">
+            An error has occurred. This application may no longer respond until reloaded.
+        </environment>
+        <environment include="Development">
+            An unhandled exception has occurred. See browser dev tools for details.
+        </environment>
+        <a href="" class="reload">Reload</a>
+        <a class="dismiss">🗙</a>
+    </div>
+
+	<script src="_content/InputLargeTextArea/js/InputLargeTextArea.js"></script>
+    <script src="_framework/blazor.server.js"></script>
+</body>
+</html>

src/InputLargeTextArea/SampleServerApp/Program.cs

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+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Web;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+builder.Services.AddRazorPages();
+builder.Services.AddServerSideBlazor();
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (!app.Environment.IsDevelopment())
+{
+    app.UseExceptionHandler("/Error");
+    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
+    app.UseHsts();
+}
+
+app.UseHttpsRedirection();
+
+app.UseStaticFiles();
+
+app.UseRouting();
+
+
+app.MapBlazorHub();
+app.MapFallbackToPage("/_Host");
+
+app.Run();

src/InputLargeTextArea/SampleServerApp/SampleServerApp.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\src\InputLargeTextArea\InputLargeTextArea.csproj" />
+  </ItemGroup>
+
+</Project>

src/InputLargeTextArea/SampleServerApp/Shared/MainLayout.razor

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+@inherits LayoutComponentBase
+
+<PageTitle>SampleServerApp</PageTitle>
+
+<div class="page">
+    <div class="sidebar">
+        <NavMenu />
+    </div>
+
+    <main>
+        <div class="top-row px-4">
+            <a href="https://docs.microsoft.com/aspnet/" target="_blank">About</a>
+        </div>
+
+        <article class="content px-4">
+            @Body
+        </article>
+    </main>
+</div>

src/InputLargeTextArea/SampleServerApp/Shared/MainLayout.razor.css

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+.page {
+    position: relative;
+    display: flex;
+    flex-direction: column;
+}
+
+main {
+    flex: 1;
+}
+
+.sidebar {
+    background-image: linear-gradient(180deg, rgb(5, 39, 103) 0%, #3a0647 70%);
+}
+
+.top-row {
+    background-color: #f7f7f7;
+    border-bottom: 1px solid #d6d5d5;
+    justify-content: flex-end;
+    height: 3.5rem;
+    display: flex;
+    align-items: center;
+}
+
+    .top-row ::deep a, .top-row .btn-link {
+        white-space: nowrap;
+        margin-left: 1.5rem;
+    }
+
+    .top-row a:first-child {
+        overflow: hidden;
+        text-overflow: ellipsis;
+    }
+
+@media (max-width: 640.98px) {
+    .top-row:not(.auth) {
+        display: none;
+    }
+
+    .top-row.auth {
+        justify-content: space-between;
+    }
+
+    .top-row a, .top-row .btn-link {
+        margin-left: 0;
+    }
+}
+
+@media (min-width: 641px) {
+    .page {
+        flex-direction: row;
+    }
+
+    .sidebar {
+        width: 250px;
+        height: 100vh;
+        position: sticky;
+        top: 0;
+    }
+
+    .top-row {
+        position: sticky;
+        top: 0;
+        z-index: 1;
+    }
+
+    .top-row, article {
+        padding-left: 2rem !important;
+        padding-right: 1.5rem !important;
+    }
+}