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[ASP.NET Core] Try SignalR 1

Masui Masanori
Programmer, husband, father I love C#, TypeScript, etc.
・3 min read

Intro

This time, I will try ASP.NET Core SignalR.

I copied a sample project from tutorials.

Environments

  • .NET 5.0.103

For authentications

  • Microsoft.EntityFrameworkCore ver.5.0.4
  • Npgsql.EntityFrameworkCore.PostgreSQL ver.5.0.2
  • Microsoft.AspNetCore.Identity.EntityFrameworkCore ver.5.0.4

package.json

{
    "dependencies": {
        "@microsoft/signalr": "^5.0.4",
        "ts-loader": "^8.0.17",
        "tsc": "^1.20150623.0",
        "typescript": "^4.2.3",
        "webpack": "^5.24.4",
        "webpack-cli": "^4.5.0"
    }
}
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SignalR + Webpack + TypeScript

Failed

Because when I don't use JavaScript frameworks or Blazor, I use Webpack and TypeScript to write client-side codes.

So I changed the sample code to fit my develop environments.
(I just changed from the JavaScript code to TypeScript)

But I got an exception.

Uncaught TypeError: Cannot read property 'HubConnectionBuilder' of undefined
    at init (main.page.ts:9)
    at eval (main.page.ts:34)
    at Object../ts/main.page.ts (mainPage.js:259)
    at __webpack_require__ (mainPage.js:282)
    at mainPage.js:322
    at mainPage.js:325
    at webpackUniversalModuleDefinition (mainPage.js:17)
    at mainPage.js:18
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Resolve

I took two mistakes.

webpack.config.js

The first one was about "webpack.config.js".

I wrote like below.

webpack.config.js

var path = require('path');
module.exports = {
    mode: 'development',
    entry: {
        'mainPage': './ts/main.page.ts',
    },
    module: {
        rules: [
            {
                test: /\.tsx?$/,
                use: 'ts-loader',
                exclude: /node_modules/
            }
        ]
    },
    resolve: {
        extensions: [ '.tsx', '.ts', '.js' ]
    },
    output: {
        filename: '[name].js',
        path: path.resolve(__dirname, 'wwwroot/js'),
        library: 'Page',
        libraryTarget: 'umd'
    }
};
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I had to add "devtool: "eval-source-map""

webpack.config.js

var path = require('path');
module.exports = {
    mode: 'development',
    entry: {
        'mainPage': './ts/main.page.ts',
    },
    module: {
...
    },
    resolve: {
        extensions: [ '.tsx', '.ts', '.js' ]
    },
    devtool: "eval-source-map",
    output: {
...
    }
};
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Import '@microsoft/signalr'

The second one was about import "@microsoft/signalr".
I wrote TS code like below.

main.page.ts

import signalR from '@microsoft/signalr';

function init() {
    const connection = new signalR.HubConnectionBuilder().withUrl("/chatHub").build();
...
}
init();
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But I had to change like below.

main.page.ts

import * as signalR from '@microsoft/signalr';

function init() {
    const connection = new signalR.HubConnectionBuilder().withUrl("/chatHub").build();
...
}
init();
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Now I can send or receive messages through SignalR.

Authentications

Because the sample doesn't have authentications, everyone can join the chat.
How can I require signing in?

First, I added codes for ASP.NET Core Identity.

After that, I only needed adding "[Authorize]" attribute into "ChatHub" class.

ChatHub.cs

using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.SignalR;

namespace SignalrSample.Hubs
{
    [Authorize]
    public class ChatHub : Hub
    {
...
    }
}
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Alt Text

Distinguish between clients

The sample sends messages to all clients.

ChatHub.cs

...
    public class ChatHub : Hub
    {
        public async Task SendMessage(string user, string message)
        {
            await Clients.All.SendAsync("ReceiveMessage", user, message);
        }
    }
...
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If I don't want to send to myself, what shall I do?

SignalR can distinguish clients.
So I just need changing like below.

ChatHub.cs

...
    public class ChatHub : Hub
    {
        public async Task SendMessage(string user, string message)
        {
            await Clients.Others.SendAsync("ReceiveMessage", user, message);
        }
    }
...
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