What is the purpose of using tsconfig.json file ?

tsconfig.json file allows you to point the root level files and different compiler options to setup that require to compile a TypeScript based projects. The existence of this file in a project specifies that the given directory is the TypeScript project folder root.

Here is an example tsconfig.json file.

{
"compileOnSave": true,
"compilerOptions": {
        "target": "es5",
		"module": "system",
		"moduleResolution": "node",
		"noImplicitAny": true,
		"sourceMap": true,
        "removeComments": false
},
	"files": [
		"program.ts",
		"sys.ts"
	],
	"include": [
		"src/**/*"
	],
	"exclude": [
		"node_modules",
		"src/**/*.spec.ts"
	]
}

Lets understand what each option specifies:

• compileOnSave: If sets true, it instructs the IDE to automatically compile the given TypeScript files and generate the output.
• compilerOptions: It allows specifying additional options to the TypeScript compiler:
  • target: the language used for the compiled output, e.g. es5, es6.
  • module: the module manager used in the compiled output. system is for SystemJS, commonjs for CommonJS.
  • moduleResolution: the strategy used to resolve module declaration files (.d.ts files). With the node approach, they are loaded from the node_modules folder like a module (require('module-name'))
  • noImplicitAny: if sets false, Raise error on expressions and declarations with an implied any type.
  • sourceMap: if sets true, it will generate source map files to debug directly your application TypeScript files in the browser,
  • removeComments: if set, Remove all comments except copy-right header comments beginning with /*!
• files: Gives a list of TypeScript files that will be included by the compiler. The URL of the files can be both relative or absolute.
• include: Allows you to include a list of TypeScript files using the glob wildcards pattern.
• exclude: Allows you to exclude a list of TypeScript files using the glob wildcards pattern.

Install TypeScript compiler in VS Code

If you need to run the typescript from VS Code terminal you need to install the typescript compiler either globally or in your workspace.

This typescript compiler will transpile the TypeScript code to JavaScript.

Following are the steps we need to install and compile TypeScript in VS Code.

• Install node.js Package Manager (npm).
• Install TypeScript globally (-g) by this command:

  npm install -g typescript
  

• If want to install TypeScript locally in a single project, you can use this command:

  npm install --save-dev typescript
  

• Test your install by checking the version.

  tsc --version
  

TypeScript HelloWorld:

Let's start with a simple Hello World example. Create a new folder HelloWorld and open in VS Code.

mkdir HelloWorld
cd HelloWorld
code .

Create a new file called helloworld.ts.

Add the following TypeScript code in helloworld.ts file.

let message: string = 'Hello World';
console.log(message);

To compile the TypeScript code, you can open the Integrated Terminal (Ctrl+`)

Run this command to compile helloworld.ts

tsc helloworld.ts

It will create a new helloworld.js JavaScript file in the same folder.

To run the javascript file, you can use this command:

node helloworld.js

It will run the javascript code and display the script output in console.

SQL Server Logins vs Database Users

Usually there is a confusion over logins and users in SQL Server, especially for new SQL Server users. Here I have summarized the points to help understand the difference between these two concepts.

SQL Login

• SQL Login is for Authentication. Authentication can decide if we have permissions to access the server or not.
• Login is created at the SQL Server instance level.
• The logins will be assigned to server roles (for example, public, serveradmin, sysadmin etc).
• Create Login:

  CREATE LOGIN [idrees_login] WITH PASSWORD = 'password-goes-here';
  

• Assign Server-Role to Login:

  ALTER SERVER ROLE [sysadmin] ADD MEMBER [idrees_login]
  

SQL User

• SQL Server User is for Authorization. Authorization decides what are different operations we can perform in a database. Permissions inside the database are granted to the database users, not the logins.
• User is created at the SQL Server database level. We can have multiple users from different databases (one user per database) connected to a single login to a server. User will always mapped to a Login.
• Users will be assigned to roles within that database (eg. db_owner, db_datareader, db_datawriter etc).
• Create User:

  CREATE USER [idrees_user] FOR LOGIN [idrees_login];
  

• Assign Database-Role to User:

  ALTER ROLE [db_owner] ADD MEMBER [idrees_user]
  

General:

• Logins only allow you to access to server. If the login is not mapped to any database user, then it will not be allowed to access any objects in the database.
• You can not have a (database) user without a (server) login.
• You cannot speficy the crendentials for user. Since user is mapped to a login, the login credentials are user for connection access. The same login credentials will be used to access all the databases for which a user is mapped.
• Within a database, the objects-level permissions will be granted/revoked on user.

SQL Server - Change Authentication mode from Windows to Sql Server Authentication

During SQL Server installation, the wizard allows to select the authentication mode. At that time you can pick the required authentication scheme as per your needs.

In case if you have selected the Windows Authentication, the server will not configure the SQL Authentication mode and will not setup the default 'sa' account.

At later time if you want to enable the SQL Authentication, following steps will be required:

1. Enable SQL Server Authentication Mode:

   • In SQL Server Management Studio Object Explorer, right-click the Server node, and then click Properties.

     

   • On the Security page, under Server authentication, select SQL Server and Windows Authentication mode. Then click OK.

     
   • When it asks you to restart the SQL Server, click OK.

2. Enable Existing Login account sa:

   • By default, the sa account remains disable (if Windows Authentication mode is selected during SQL Server installation).

     First step is to enable sa login.

     ALTER LOGIN sa ENABLE ;
     GO
     

   • Second step is to set strong password for login sa.

     ALTER LOGIN sa WITH PASSWORD = '[enter-strong-password-here]';
     GO
     

.NET Core - asp-append-version tag helper

To have better user experience and improve website's performance, modern browsers used to cache the static files like css, js and images. While it helps your website to perform better but it could also lead to serve stale files. If you have made any changes to your css, js or image files, the browsers will keep showing the old images until it refreshes it cache. Sometimes the users have to do a full refresh (Ctrl + F5 or Ctrl + R) for the browser to get latest or fresh content of these files.

In this case we need to tell the browser to get the new files from server to make sure that the user will always be served with latest files without doing full refresh on the browser.

Some ways to acheive this behavior could be:

1. Every time you make any changes in the file content, also change the file name and its references.
2. Another way is to add a random string behind the js, css or image url.

Here we will use the second approach to add a random string for these files urls.

The good news is that ASP.NET Core has in-build feature for this issue. We can use the tag helper:

asp-append-version="true" 

To enable this feature ON for particualr static file, we just need to add the above asp-append-version tag-helper/attribute as below.

CSS
<link rel="stylesheet" href="~/css/site.css" asp-append-version="true" />    
JS 
<script src="~/js/site.js" asp-append-version="true"></script>
Image
<img src="~/images/logo.png" asp-append-version="true" />

After making these changes you can check the rendered html from browser source code or inspect element using browser's developer tools. It will be found that there is a random string attached behind file name.

If you make any change within the file content for css/js etc, when the next time browser will render it, it will fetch the fresh file from server because of different random string attached to the file URL.

CSS
https://localhost:7163/css/site.css?v=1Ip96t8Xk8GevF37Kz0Wu_1tuNyEZJcH5PYrmiK1fNs

JS
https://localhost:7163/js/site.js?v=mC13cRUFjf1YiinDRFWfv-eOXac88lLptssglYLhYtQ

You will see a different random string appended each time the changes are made to the file cotent, which makes sure that the browser will fetch the latest copy from server.