Caching can help improve the performance of an ASP.NET Core application. Distributed caching is helpful when working with an ASP.NET application that’s deployed to a server farm or scalable cloud environment. Microsoft documentation contains examples of doing this with SQL Server or Redis, but in this post,I’ll show you an alternative. 

Iconoir: 1300+ Open Source SVG Icons — A vast array of clean and simple icons, complete with ways to quickly integrate them into React, React Native, Figma, and other apps – or just using CSS, if you prefer. 

C# Language Features by Versions
This page contains all the features introduced to C# with a link to all the proposals and documentation.
This is a great way to find out if you are missing out on new features that can make your developer life easier. 

using System;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

namespace MvcApplication1.Models
{
    public class Task
    {
        public int Id { set; get; }

        [Required]
        public string Name { set; get; }

        [DisplayName("Due Date")]
        public DateTime? DueDate { set; get; }

        [DisplayName("Is Complete")]
        public bool IsComplete { set; get; }

        [StringLength(450)]
        public string Description { set; get; }
    }
}

Install-Package MvcScaffolding

Attempting to resolve dependency 'T4Scaffolding'.
Attempting to resolve dependency 'T4Scaffolding.Core'.
Attempting to resolve dependency 'EntityFramework'.
Successfully installed 'T4Scaffolding.Core 1.0.0'.
Successfully installed 'T4Scaffolding 1.0.8'.
Successfully installed 'MvcScaffolding 1.0.9'.
Successfully added 'T4Scaffolding.Core 1.0.0' to MvcApplication1.
Successfully added 'T4Scaffolding 1.0.8' to MvcApplication1.
Successfully added 'MvcScaffolding 1.0.9' to MvcApplication1.

Scaffold Controller Task

Scaffold Controller -ModelType Task -ControllerName TasksController -DbContextType TasksDbContext

Scaffold Controller -ModelType Task -ControllerName TasksController -DbContextType TasksDbContext -Repository

Scaffold Controller -ModelType Task -ControllerName TasksController -DbContextType TasksDbContext -Repository -Force

public interface ITaskRepository : IDisposable
{
  IQueryable<Task> All { get; }
  IQueryable<Task> AllIncluding(params Expression<Func<Task, object>>[] includeProperties);
  Task Find(int id);
  void InsertOrUpdate(Task task);
  void Delete(int id);
  void Save();
}

A set of tslint rules for static code analysis of Angular TypeScript projects.
You can run the static code analyzer over web apps, NativeScript, Ionic, etc.

Firefox Quantum is over twice as fast as Firefox from 6 months ago, built on a completely overhauled core engine with brand new technology stolen from our advanced research group, and graced with a beautiful new look designed to get out of the way and let you do what you do best: surf a ton of pages, open a zillion tabs, all guilt free because Firefox Quantum uses less memory than the competition 

@if (HotelRoomModel.HotelRoomImages.Count > 0)
{
    var serial = 1;
    foreach (var roomImage in HotelRoomModel.HotelRoomImages)
    {
        <div class="col-md-2 mt-3">
            <div class="room-image" style="background: url('@roomImage.RoomImageUrl') 50% 50%; ">
                <span class="room-image-title">@serial</span>
            </div>
            <button type="button"
                    @onclick="()=>DeletePhoto(roomImage)"
                    class="btn btn-outline-danger btn-block mt-4">Delete</button>
        </div>
        serial++;
    }
}

@code
{
    private const string UploadFolder = "Uploads";

    private void DeletePhoto(HotelRoomImageDTO imageDto)
    {
        var imageFileName = imageDto.RoomImageUrl.Replace($"{UploadFolder}/", "", StringComparison.OrdinalIgnoreCase);
        if (HotelRoomModel.Id == 0 && Title == "Create")
        {
            FileUploadService.DeleteFile(imageFileName, WebHostEnvironment.WebRootPath, UploadFolder);
            HotelRoomModel.HotelRoomImages.Remove(imageDto);
        }
    }
}

@code
{
    private List<string> DeletedImageFileNames = new List<string>();

    private void DeletePhoto(HotelRoomImageDTO imageDto)
    {
        var imageFileName = imageDto.RoomImageUrl.Replace($"{UploadFolder}/", "", StringComparison.OrdinalIgnoreCase);
        if (HotelRoomModel.Id == 0 && Title == "Create")
        {
            // ...              
        }
        else
        {
            // Edit Mode
            DeletedImageFileNames.Add(imageFileName);
            HotelRoomModel.HotelRoomImages.Remove(imageDto); // Update UI
        }
    }

    private async Task HandleHotelRoomUpsert()
    {
        // ...
 
        if (HotelRoomModel.Id != 0 && Title == "Update")
        {
            // Update Mode
            var updatedRoomDto = await HotelRoomService.UpdateHotelRoomAsync(HotelRoomModel.Id, HotelRoomModel);

            foreach(var imageFileName in DeletedImageFileNames)
            {
                FileUploadService.DeleteFile(imageFileName, WebHostEnvironment.WebRootPath, UploadFolder);
            }

            // await AddHotelRoomImageAsync(updatedRoomDto);
            await JsRuntime.ToastrSuccess($"The `{HotelRoomModel.Name}` updated successfully.");
        }
        else
        {
           // ... 
        }
    }
}

.spinner {
  border: 16px solid silver !important;
  border-top: 16px solid #337ab7 !important;
  border-radius: 50% !important;
  width: 80px !important;
  height: 80px !important;
  animation: spin 700ms linear infinite !important;
  top: 50% !important;
  left: 50% !important;
  transform: translate(-50%, -50%);
  position: absolute !important;
}

@keyframes spin {
  0% {
    transform: rotate(0deg);
  }

  100% {
    transform: rotate(360deg);
  }
}

@code
{
    private bool IsImageUploadProcessStarted;

    private async Task HandleImageUpload(InputFileChangeEventArgs args)
    {
        try
        {
            IsImageUploadProcessStarted = true;
            // ...
        }
        finally
        {
            IsImageUploadProcessStarted = false;
        }
    }
}

<InputFile OnChange="HandleImageUpload" multiple></InputFile>
<div class="row">
@if (IsImageUploadProcessStarted)
{
    <div class="col-md-12">
        <span><i class="spinner"></i> Please wait.. Images are uploading...</span>
    </div>
}

@using BlazorServer.App.Pages.Components

<Confirmation @ref="Confirmation1"
    OnCancel="OnCancelDeleteImageClicked"
    OnConfirm="@(()=>OnConfirmDeleteImageClicked(ImageToBeDeleted))">
    <div>
        Do you want to delete @ImageToBeDeleted?.RoomImageUrl image?
    </div>
</Confirmation>

    private Confirmation Confirmation1;
    private HotelRoomImageDTO ImageToBeDeleted;

    private void OnCancelDeleteImageClicked()
    {
        // Confirmation1.Hide();
    }

    private void DeletePhoto(HotelRoomImageDTO imageDto)
    {
        ImageToBeDeleted = imageDto;
        Confirmation1.Show();
    }

    private void OnConfirmDeleteImageClicked(HotelRoomImageDTO imageDto)
    {

<td>
    <NavLink href="@($"hotel-room/edit/{room.Id}")" class="btn btn-primary">Edit</NavLink>
    <button class="btn btn-danger" @onclick="()=>HandleDeleteRoom(room)">Delete</button>
</td>

<Confirmation @ref="Confirmation1"
    OnCancel="OnCancelDeleteRoomClicked"
    OnConfirm="OnConfirmDeleteRoomClicked">
    <div>
        Do you want to delete @RoomToBeDeleted?.Name?
    </div>
</Confirmation>

@code
{
    private List<HotelRoomDTO> HotelRooms = new List<HotelRoomDTO>();
    private HotelRoomDTO RoomToBeDeleted;
    private Confirmation Confirmation1;

    private void OnCancelDeleteRoomClicked()
    {
        // Confirmation1.Hide();
    }

    private void HandleDeleteRoom(HotelRoomDTO roomDto)
    {
        RoomToBeDeleted = roomDto;
        Confirmation1.Show();
    }

    private async Task OnConfirmDeleteRoomClicked()
    {
        if(RoomToBeDeleted is null)
        {
            return;
        }

        await HotelRoomService.DeleteHotelRoomAsync(RoomToBeDeleted.Id);
        HotelRooms.Remove(RoomToBeDeleted); // Update UI
    }

An exception occurred while iterating over the results of a query for context type 'BlazorServer.DataAccess.ApplicationDbContext'.
System.InvalidOperationException: A second operation was started on this context before a previous operation completed.
This is usually caused by different threads concurrently using the same instance of DbContext.
For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

So, last week one of my colleagues wanted to serialize an object along with custom property attribute to JSON. Interesting… JSON.NET by default will not allow serializing custom property attribute. So, you have to write custom JSON converter to fix this. Let’s take a look at how 

An extremely simple and responsive jQuery plugin that allows you to create multi-level drop down menu with subtle effects (sliding, fading, scale up, or scale down).  Each sub-menu in this menu will be shown in its own context, making the “parent” level disappear, good for saving space for menus which have a lot of content

If you enable our semantic highlighting support then, be sure to try out the included Visual Studio 2019 Light and Dark themes. TypeScript looks great in it too!

NOTE: For semantic highlighting ensure that editor.semanticHighlighting.enabled and csharp.semanticHighlighting.enabled are set to true.