Web Development topics

Blazor parameter passed by reference

RichardB1640 — Thu, 26 Feb 2026 09:58:37 GMT

I got the impression that in Blazor parameters are always effectively passed by value which is why you need to use EventCallback for two-way binding to send a change in the parameter value back up to the component that passed it.

But not so; reference types really are passed by reference.

Therefore if a child component updates a parameter value that is a reference type then the value in the parent is changed and all you need to do is call `StateHasChanged` on the parent.

Is this as intended?

Have I misunderstood the documentation?

Example:

https://drive.google.com/file/d/1i1Rh36nHU1Z2voyHDtLVZ9GyziLw9AQq/view?usp=sharing

(Don't seem to be able to attach here and it's not really feasible to inline a whole Blazor project.)

SharePoint List View Threshold Error while Fetching 5000+ Records in list.

AjayM — Tue, 24 Feb 2026 03:49:05 GMT

I am fetching data from a SharePoint list that contains more than 5000 records inside my function. While retrieving the data, I am getting the following error:

“Flow Reminders→ The attempted operation is prohibited because it exceeds the list view threshold.”

Scenario:

The SharePoint list has 5000+ items.
Data is being fetched programmatically.
The error occurs during query execution.

What I need help with
What is the recommended and best-practice approach to retrieve large datasets from a SharePoint list without hitting the list view threshold?
Questions:

What is the recommended approach to fetch large data from a SharePoint list without hitting the list view threshold?

Any suggestions, examples, or documentation references would be greatly appreciated.

Thanks.

It appears and error that does not exist

lmobarq — Sat, 13 Dec 2025 06:15:30 GMT

I am using VS 2022 Community and when i develope asp.net apps it happens sometimes that it appears an error that does not exist adn only after many hours of searching for the error or rewriting the same code the app begins to run correctly. Somehitng simmilar happened to any of you ? how can i avoid these strange behaviour of the compiler ?

Thank you in advance

Luis Martin

Connect .Net (4.6.2) to Dataverse using the Dataverse plugin

AjayM — Tue, 09 Dec 2025 07:18:58 GMT

Hi Microsoft Tech Community,

We have a Dataverse environment in our tenant, and I have its URL. I'm building a .NET application and need to connect it to Dataverse for data access.

From the Learn docs, ChatGPT, and Copilot, it seems I need to use an App ID (Client ID) and Client Secret in the connection string (e.g., via Microsoft.PowerPlatform.Dataverse.Client). However, the Dataverse environment itself doesn't expose any App ID or Client Secret—where would I even find those if they exist?

Here's the code snippet we found online that's using OAuth with AppId and RedirectUri, but we're unsure about the app registration part:

using Microsoft.Crm.Sdk.Messages; using Microsoft.PowerPlatform.Dataverse.Client; using Microsoft.Xrm.Sdk; class Program { // TODO Enter your Dataverse environment's URL and logon info. static string url = "https://yourorg.crm.dynamics.com"; static string userName = "email address removed for privacy reasons"; static string password = "yourPassword"; // This service connection string uses the info provided above. // The AppId and RedirectUri are provided for sample code testing. static string connectionString = $@" AuthType = OAuth; Url = {url}; UserName = {userName}; Password = {password}; AppId = 51f81489-12ee-4a9e-aaae-a2591f45987d; RedirectUri = app://58145B91-0C36-4500-8554-080854F2AC97; LoginPrompt=Auto; RequireNewInstance = True"; static void Main() { //ServiceClient implements IOrganizationService interface IOrganizationService service = new ServiceClient(connectionString); var response = (WhoAmIResponse)service.Execute(new WhoAmIRequest()); Console.WriteLine($"User ID is {response.UserId}."); // Pause the console so it does not close. Console.WriteLine("Press the <Enter> key to exit."); Console.ReadLine(); } }

Do I need to create a separate app registration in Microsoft Entra ID (Azure AD), link it to the Dataverse environment (perhaps as an application user?), and then use that app's Client ID/Secret in my .NET code? If so, could someone outline the exact steps, including permissions and Power Platform admin center setup?

Any guidance or links to official walkthroughs would be greatly appreciated—thanks!

Debug Asp.Net - "This site can't be reached"

EduardoFornaro — Wed, 15 Oct 2025 22:35:40 GMT

Hello,

Today, all my Visual Studio 2019 Community projects stopped debugging and are displaying the following message in the browser: "This site can't be reached."

I've tried using Visual Studio 2022 Community, but the problem is the same. I have numerous projects (Asp.Net - vb), and they all have the same issue. Even creating a new project (VS 20219 or VS 2022), the error persists. I've tried reinstalling IIS Express, disabling my antivirus, and reinstalling Visual Studio 2022 (since it was just for testing). Nothing works.

Everything was working until yesterday, but now I can't work anymore. It seems like a Windows update, but I don't have restore points to revert to.

I'd appreciate it if anyone has any idea what this could be.

Eduardo

Debugging Java script in old asp core app

RobertWarning — Sun, 07 Sep 2025 21:13:19 GMT

Hy, I need to modify an asp.net.core app witch I made years ago. in version 2.2. I do succeed to alter C# code in visual studio (2022), but I need to alter also some Java script. The problem is that if I try to do so and I want to debug it it seems that the script in my browser (MS Edge) is not changing.

I have enabled Java script debugging in VS. I emptied the browsers cache but nothing seems to help. When I run the application in debugging mode and hit F12 I still see the old script.

Please help!

Is Native RDLC Report Support Planned for Future .NET Versions?

Velkumar — Tue, 19 Aug 2025 06:39:36 GMT

Good day Team,

Given the demand for cross-platform reporting solutions, is there any plan to provide native RDLC (Report Definition Language Client-side) support for .NET Core or upcoming .NET releases (e.g., .NET 9 and beyond)? Many enterprise applications rely on RDLC, and the current lack of official support limits modernization efforts and forces continued reliance on the legacy .NET Framework or Windows-only workarounds.

Is RDLC on the roadmap for future .NET versions, or should we consider alternative technologies for long-term reporting requirements? Any official guidance or updates would be greatly appreciated.

Creating a pooled resource for Dependency Injection

WhiteEagle5150 — Fri, 08 Aug 2025 16:58:55 GMT

Currently, we have AddSingleton(), AddScoped(), and AddTransient() to generate resources in DI.

Is there a way to request a new feature for an AddPooled() which will allow us to create and reuse unused instances from a pool?

I have a class that has an expensive creation (a little over 5 seconds) that cannot be instantiated as a singleton. I don't need it to maintain any state, so it would be an ideal candidate for a pooled resource in DI.

When should I use SQL Server, MySQL, or PostgreSQL?

UdhayarajanJ — Tue, 05 Aug 2025 10:28:41 GMT

I'm working on a web application (using C#/.NET backend), and I need to choose a relational database. I'm considering three options:

Microsoft SQL Server
MySQL
PostgreSQL

I want to understand:

What are the strengths and weaknesses of each?
Which database is better suited for:
1. Transactional performance
2. Advanced querying / analytics
3. Ease of use with .NET
4. Cross-platform support
Are there any licensing or hosting concerns I should consider?

My use case involves:

Moderate traffic
Complex queries with joins
APIs and background jobs
Deployment to cloud (Azure)

I’d appreciate any recommendations or real-world experience comparing these databases.

Help with my ASP.NET API Application

bibash — Thu, 15 May 2025 16:18:12 GMT

I have been developing API for a full stack application with React FrontEnd in ASP.NET for my Internship project which is an Asset Management System. I have successfully implemented API Endpoints for CRUD with Authentication with JWT. What topic should I learn next ? Should I start providing API Documentation or is there something else I need to learn ? I have also uploaded the Schema the project is using.

I am using ADO.NET instead of Entity Framework for quering with the database. The link to my Repository Source Code: https://github.com/bibashmanjusubedi/Internship

Singleton Class with Async

GarudaLead — Thu, 15 May 2025 12:53:37 GMT

I'm working on building a Blazor Web App (.net 9) for an internal company portal.

I want to load some persistent data to be used throughout the app into a class and then load that class as a scoped service.

Most of the data will be fairly static, but expensive data to retrieve, ie: graph api call for members of groups, etc. So that data will also be loaded asynchronously.

Everything I've found regarding loading data into a class asynchronously basically points back to a post by Stephen Cleary on Asynchronous Lazy Initialization: https://blog.stephencleary.com/2012/08/asynchronous-lazy-initialization.html

My question is, given that this post was originally posted back in 2012, is this still an acceptable way of loading data asynchronously for a singleton or are there other, more modern approaches to this scenario?

aspnet c# iterate control in listview and remove a panel from placeholder in one column

canalso — Tue, 13 May 2025 03:59:20 GMT

trying to iterate through controls in listview to remove panel01 from placeholder if detected row in database condition dt.Rows[i]["BidEndWithError"].ToString() == "no" in the row:
But all the listview's panel01 being removed even dt.Rows[i]["BidEndWithError"].ToString() == "no" is not 'no'`your text`

`<asp:PlaceHolder ID="phLabel" runat="server">
<asp:Panel ID="panel01" runat="server">
Day Left : <%# Eval("BidDayLeft") %></br>
Hour Left : <%# Eval("BidHourLeft") %></br>
Minute Left : <%# Eval("BidMinuteLeft") %></br>
Second Left : <%# Eval("BidSecondLeft") %></br>
</asp:Panel>
protected void lv01_ItemDataBound(object sender, ListViewItemEventArgs e)
{

if (e.Item.ItemType == ListViewItemType.DataItem)
{
string constr = ConfigurationManager.ConnectionStrings["bidsystemdb"].ConnectionString;
using (SqlConnection con = new SqlConnection(constr))
{
DataTable dt = new DataTable();
//string strSQL = "Select * from BidTable2 WHERE ProductName='Toy 1'";
string strSQL = "Select * from BidTable2";
SqlDataAdapter adpt = new SqlDataAdapter(strSQL, con);
adpt.Fill(dt);

for (int ij = 0; ij < e.Item.Controls.Count; ij++)
{
for (int i = 0; i < dt.Rows.Count; i++)
{
//Response.Write("lv01 reached!");
if (dt.Rows[i]["BidEndWithError"].ToString() == "no")
{
Response.Write("lv01 level 2 reached!");
PlaceHolder _phLabel = e.Item.Controls[ij].FindControl("phLabel") as PlaceHolder;
Panel _pnlLabel = e.Item.Controls[ij].FindControl("panel01") as Panel;
_phLabel.Controls.Remove(_pnlLabel);
ContentPlaceHolder _MainContent = Master.FindControl("MainContent") as ContentPlaceHolder;
UpdatePanel _udp01 = _MainContent.FindControl("udp01") as UpdatePanel;
_udp01.Update();
}
}
}
}
}
}`

Implementation SMTP using MailKit in ASP .NET Core MVC

soumyadipmajumder03 — Fri, 25 Apr 2025 20:17:18 GMT

I am developing a web development project, where I have to implement email trigger along with message. Suppose there is a form where users will put thier name, email, title and message. After hitting submit button it will automatically send the message to the owner. How can I achieve this in latest version of this framework. And MailKit is Version 4.11.0.

Enable .Net ImageFormat.WebP in VS 2022 Prof ASPX Web.Config

PeterS1 — Tue, 15 Apr 2025 02:07:24 GMT

Hi.

I am developing C# ASPX Web sites in VS Professional 2022 (64 bit).

I want to access the System.Drawing.Imaging.ImageFormat.WebP property so I can manipulate WebP files. I believe this requires .Net 4.8.

I know there are 3rd party libraries out there - I would prefer to keep as much native MS code as possible.

I am unable to get System.Drawing.Imaging.ImageFormat.WebP as a selection option for the ImageFormat.

I can get all of the other formats e.g. TheImageFormat = System.Drawing.Imaging.ImageFormat.Jpeg/Gif/Png etc. WebP is not shown as an option.

I have Web.Config set as:

<compilation optimizeCompilations="true" debug="true" targetFramework="4.8.1"> <assemblies> <add assembly="System.Net, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" /> <add assembly="System.Numerics, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" /> </assemblies> </compilation> <httpRuntime targetFramework="4.8.1" executionTimeout="240" maxRequestLength="20480" requestValidationMode="2.0" />

The Targeting Packs & SDK seem to be installed & enabled as per the screen snap below.

Any help in resolving this is greatly appreciated.

Many thanks, Peter.

Build Scalable Web Apps and APIs with ASP.NET Core, Blazor, Angular for Modern Web Apps

BENDA_N — Tue, 01 Apr 2025 07:20:52 GMT

I’m starting this discussion because many developers today need guidance on how to build modern, scalable web applications and APIs by combining ASP.NET Core, Blazor, and Angular—three powerful technologies within the .NET ecosystem. Whether you're focused on server-side development, creating dynamic client-side apps, or integrating both, these frameworks provide incredible capabilities to enhance your projects

ASP.NET Core for API Development: ASP.NET Core is a robust, high-performance framework that allows you to create powerful APIs. Some of the best practices we’ll cover include:
- Designing RESTful APIs with ASP.NET Core
- Utilizing Entity Framework Core for efficient database access
- Securing APIs with JWT and OAuth
- Handling asynchronous requests for optimal performance
- Implementing API versioning and changes over time
Building Dynamic Web Apps with Blazor: Blazor enables you to create interactive web applications using C# instead of JavaScript. We will discuss:
- Blazor Web Assembly vs. Blazor Server: Differences and use cases
- Creating reusable Blazor components for UI
- Integrating third-party JavaScript libraries with Blazor
- Using SignalR for real-time features
- Optimizing Blazor for performance
Angular for Full-Featured Client-Side Development: Angular is a powerful, full-featured front-end framework that excels in creating dynamic and complex user interfaces. In this section, we'll dive into:
- Why you might choose Angular over Blazor in certain cases
- Using Angular CLI to scaffold, build, and maintain apps
- Managing state in Angular with NgRx or RxJS
- Connecting Angular with ASP.NET Core APIs for data handling
- Working with Angular components, services, and routing for a seamless user experience
Combining Angular and Blazor in a Single Application: You may have use cases where you want to combine both Blazor and Angular in one application to leverage the strengths of each framework:
- When to use Angular for complex frontend features (e.g., dynamic forms, complex data visualization) and Blazor for simpler components or backend-heavy apps.
- Managing communication between Angular and Blazor components in a single page (e.g., using - JavaScript Interop to pass data between the two).
- Handling authentication and state management across both frameworks.
Integration between Frontend (Blazor/Angular) and Backend (ASP.NET Core): No matter whether you're using Angular or Blazor for the frontend, integrating these with your backend API is key. We'll discuss:
- Setting up HttpClient for making API calls from both Blazor and Angular
- Working with SignalR to enable real-time features in both frontends
- Managing authentication and authorization across both Angular and Blazor (JWT, OAuth)
- Best practices for passing data and sharing state between the frontend and backend
Scalable and Maintainable Web Apps: When building full-stack web applications, it's important to focus on scalability and maintainability. Here are some practices for achieving this:
- Structuring your application code to separate concerns (e.g., services, components, repositories)
- Utilizing Dependency Injection for flexible and testable code
- Modularizing your codebase for easier updates and maintenance
- Using Lazy Loading for Angular and Blazor components to improve performance
- Leveraging Caching strategies to enhance response times
Testing and Continuous Deployment: For any modern application, testing and deployment are crucial. We’ll discuss:
- Unit and integration testing in ASP.NET Core, Blazor, and Angular
- Automated end-to-end testing (e.g., with Cypress for Angular, bUnit for Blazor)
- Continuous Integration/Continuous Deployment (CI/CD) strategies for seamless deployment to cloud platforms like Azure or AWS
When to Choose Angular, Blazor, or Both: It’s essential and interesting to know when to use each of these frameworks depending on your project’s needs. Some scenarios we’ll explore:
- When to go for Blazor for a unified C# experience in both frontend and backend
- Why you might opt for Angular when building highly interactive, feature-rich web applications
- Hybrid approaches where you can use Blazor and Angular together for a robust full-stack solution

SO:

Combining ASP.NET Core, Blazor, and Angular allows developers to choose the right tool for the right job, creating flexible, scalable, and maintainable web applications. Whether you’re leveraging Blazor for its deep integration with .NET or Angular for its powerful frontend capabilities, these technologies offer a powerful suite of tools to build modern web applications.

What are your thoughts? How have you integrated Angular or Blazor with ASP.NET Core in your projects? Share your experiences and challenges, and let's collaborate on solutions!

Blazor server app closes without error during debugging

Kocahoctpa — Wed, 26 Mar 2025 14:29:14 GMT

The application started in debug mode stops reacting unexpectedly, without errors being intercepted and/or exceptions being generated.
I don't know if this behavior can also happen when starting in release mode.
In practice, the web application stops reacting in the browser. However, if I pause the execution in Visual Studio, a message warns me that the debug has timed out because the underlying application is no longer running.

The attempts I made to solve the problem are:
I tried to hook the unhandled errors with: AppDomain.CurrentDomain.UnhandledException += (handling code)
But unhandled errors are not intercepted.

I tried to remove the automatic start of the browser when the app starts in order to disconnect the closing of the browser with the end of the execution of the application.

It does not solve the problem.

Notes:
It is a Blazor server application, it uses .NET 9 (but even with .NET 8 I encountered the problem).
I updated visual studio, and all the nughet packages connected to the application.

The application, terminating without there being any clues as to the cause because the debugging does not stop anywhere, can no longer be fixed.

Thanks

I tried to catch unhandled errors, but it seems that the app does not close due to exceptions during execution (debugging does not catch errors).
I use Edge browser. I tried to remove breakpoints from the code.

C# code causing XSS vulnerability

Jerry8989- — Thu, 20 Mar 2025 19:02:52 GMT

Hello,

We get a vulnerability scan that is show that one of my pages is susceptible to a XSS attack. We are using a telerik tree view to display different data when the nodes are expanded. This is the information they reported back to me.

Issue Detail

The value of the scrollPosition JSON parameter within the ctl00_ContentPlaceHolder1_VIndex2_tvIndex_ClientState parameter is copied into the HTML document as plain text between tags. The payload sbi7s<script>alert(1)</script>tx52l was submitted in the scrollPosition JSON parameter within the ctl00_ContentPlaceHolder1_VIndex2_tvIndex_ClientState parameter. This input was echoed unmodified in the application's response.

Request

older1_VIndex2_tvIndex_ClientState=%7b%22expandedNodes%22%3a[]%2c%22collapsedNodes%22%3a[]%2c%22logEntries%22%3a[]%2c%22selectedNodes%22%3a[]%2c%22checkedNodes%22%3a[]%2c%22scrollPosition%22%3a%220**sbi7s%3cscript%3ealert(1)%3c%5c%2fscript%3etx52l**%22%7d&ctl00_RadWindowManager1_ClientState=&__ASYNCPOST=true&ctl00%24ContentPlaceHolder1%24VIndex2%24btnAddCart=Add%20To%20Cart

Response

> HTTP/2 200 OK
> Cache-Control: no-cache
> Pragma: no-cache
> Content-Type: text/plain; charset=utf-8
> Expires: -1
> Server: Microsoft-IIS/10.0
> X-Powered-By: ASP.NET
> X-Frame-Options: SAMEORIGIN
> X-Ua-Compatible: IE=edge,IE=11,IE=10,IE=9,IE=8,IE=7
> Strict-Transport-Security: max-age=31536000
> Date: Wed, 19 Mar 2025 16:26:27 GMT
> Content-Length: 82
> 68|error|500|0**sbi7s<script>alert(1)</script>tx52l** is not a valid value for Int32.|

What is the best way to pinpoint this issue? How do I fix this so it isn't showing up on the scans?

.NET Core render modes

baroo — Wed, 19 Mar 2025 20:59:30 GMT

I moved my Blazor webassembly application form .NET 8 to .NET 9. Previously it was basicly two projects:

Client (static webassembly content served in docker by nginx on port 5007 with API address set to port 5007)
Server (database app with API on port 5009)

and the typical usage was that I connect in the browser to port 5007, webassembly content was downloaded to the browser and display data gathered form the API on port 5007. After migration to .NET 9 I can no loger download web assemby package (connection reset), but instead everything is served on port 5009 (old webassemby content and API). Moreover everything is working considerably faster but I`m confused:

Why and how it is even working (how content from client appear in the server)?
Which render mode I`m using currently?
Do I still need my second container with nginx?
How should I clean my Startup.cs in the Server project after taht migration?

namespace eTabelki.Server { public class Startup { readonly string CorsOrigins = "CorsOrigins"; public Startup(IConfiguration configuration) { Configuration = configuration; } public IConfiguration Configuration { get; } // This method gets called by the runtime. Use this method to add services to the container. // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940 public void ConfigureServices(IServiceCollection services) { services.AddDbContext<ApplicationDbContext>(options => options.UseSqlite(Configuration.GetConnectionString("DefaultConnection"))); services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies()); services.AddControllersWithViews(); services.AddRazorPages().AddJsonOptions(options => { options.JsonSerializerOptions.ReferenceHandler = System.Text.Json.Serialization.ReferenceHandler.Preserve; options.JsonSerializerOptions.PropertyNamingPolicy = null; }); services.AddCors(options => { options.AddPolicy(CorsOrigins, builder => builder.WithOrigins("http://10.0.10.3:5007", "https://10.0.10.3:5008") .AllowAnyOrigin() .AllowAnyMethod() .AllowAnyHeader()); }); services.AddTransient<IGenerateInvoiceService, GenerateInvoiceService>(); services.AddTransient<IExportService, ExportService>(); } // This method gets called by the runtime. Use this method to configure the HTTP request pipeline. public void Configure(IApplicationBuilder app, IWebHostEnvironment env) { if (env.IsDevelopment()) { app.UseDeveloperExceptionPage(); app.UseWebAssemblyDebugging(); using (IServiceScope scope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope()) { var context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>(); context.Database.Migrate(); ApplicationDbContextExtensions.EnsureSeedData(context).GetAwaiter().GetResult(); ApplicationDbContextExtensions.EnsureSeedTemplates(context).GetAwaiter().GetResult(); } } else { 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(); using (IServiceScope scope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope()) { var context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>(); context.Database.Migrate(); ApplicationDbContextExtensions.EnsureSeedTemplates(context).GetAwaiter().GetResult(); } } var cultureInfo = new CultureInfo("pl-PL"); CultureInfo.DefaultThreadCurrentCulture = cultureInfo; CultureInfo.DefaultThreadCurrentUICulture = cultureInfo; app.UseHttpsRedirection(); app.UseBlazorFrameworkFiles(); app.UseStaticFiles(); app.UseRouting(); app.UseCors(CorsOrigins); app.UseEndpoints(endpoints => { endpoints.MapRazorPages(); endpoints.MapControllers(); endpoints.MapFallbackToFile("index.html"); }); } } }

Newbie here

geeksprep — Wed, 19 Mar 2025 16:34:12 GMT

Hi everyone, newbie here!

I’m excited to join the community. Feel free to ask any questions, and I’ll do my best to help out or learn together! Looking forward to getting involved!

Join return red in visual studio

tomtom2x — Thu, 27 Feb 2025 07:33:57 GMT

Hi everyone,

I am newbe in .NET Core, please info what's wrong in my code?

i want to join query using EF, but inside the visual studio tools, my join query return red.

please see attached image bellow:

the join return underline red so i can't run the project. how to fixed it?

Thankyou and best regards.