DEV Community: badalkhatri

Deno + JWT

badalkhatri — Sun, 14 Jun 2020 09:31:24 +0000

In this application, I am going to create simple JWT encode and decode functions.

First of all, we need to import two libraries or JWT from Deno's 3rd party packages

validateJwt — it will be used to validate our JWT token
makeJwt— it will convert our payload into JWT token
Jose — it indicates algorithm and type
Payload— it is interface for our Payload or Data

Encode

First of all we will put our data which into payload by using Payload interface (it is mandatory).
Then we will define our header which will contains algorithm and type.
Now we will pass header, payload and key (for simplicity I have put this key in same file but it should be placed in Environment Variable)

This function will return Promise that will contains our JWT token, we can also put expiration time in our payload.

Decode

In this function we will simply take the JWT string and pass it into validateJwt function with the key.

We will extract our payload from the return data.

Using this functions I have made simple REST API /encode and /decode.

You can checkout the code for more from my repository here

badal-khatri-blogs / deno-jwt

Happy coding :)

Thank you

How to generate dynamic ENUM type in GraphQL from DataBase using NestJS, MongoDB

badalkhatri — Sun, 24 May 2020 10:54:42 +0000

In this article I am gonna show how to generate Enum type of GraphQL by fetching data from Database in NestJS, I am using MongoDB as my Database with Mongoose, you can use any database.

I am taking example of User, in which I am storing user’s firstName, lastName and role, for role I want to make an Enum which will be dynamically generated from the roles available in the role table in Database. Also, I am dynamically resolving the selected role to the corresponding id of that role, so that way I can store the id of role in my user record.

First of all I’ll fetch all the record of role table

Then I’ll extract all the name field of role in roleNames variable,

In this filter and map function tweaks I have returned an array containing string of all roles.

As you can see I have discarded ‘ADMIN’ as I don’t want that user can select ‘ADMIN’ role by his own, to add admin user we might want to use seed data.

Now I will generate Enum string,

By joining all the roleNames with ‘ ’(single space) we will have Enum type for UserRole ready, but its just string we didn’t put it in actual GraphQL file, will do it in a short time, before that let us resolve that roles to its corresponding id so that I can easily store it in user table.

As you can see, I am making an object of UserRole which has property as role name and value as role id,

So, every role will have its corresponding role id.

Now we have generated Enum and its resolver, we have to put it in GraphQL, for that we have to put both of them in GraphQL options, which is executed every time you run the project.

So that’s it you have successfully generated Enum type in GraphQL which is dynamically generated based on data in database.

Let us have a look at what GraphQL playground looks like,

As I have only 2 roles ‘STUDENT’ and ‘TEACHER’ in my DB, GraphQL shows me those 2 as suggestion in role field.

You can go to my GitHub to get whole code for this NestJS project.

Thank you.

Happy coding!

A very simple REST API built-in Deno using oak 3rd party module

badalkhatri — Sun, 17 May 2020 10:24:26 +0000

In this post I am going to show simple REST API using Deno (an alternative of Node.js)

I am going to make 2 routes, one for GET request and other is POST request, I have taken an example to get and add users which are stored in an array, we can also store into the database but I want to make this app simple.

For simplicity I have put the whole code in a single file, you can use a modular approach too.

As I am using ‘oak’ 3rd party library we will need to import it first into our file

You can find it on — https://deno.land/x/oak

Application — The Application class wraps the serve() function from the http package.
Router — The Router class produces middleware that can be used with an Application to enable routing based on thepathname of the request.

Let us make an interface for User, as Deno out of the box supports TypeScript

Now let us store dummy data of the user in an array

This can also be fetched from database but that would make this post bit longer

Now as I mentioned above I want to make 2 routes for GET and POST, for that I am going to make 2 functions.

To get all the user

You might wondering what is context, it just hold request, response related values, as you can see i am sending response using response.body of context

To Add new users

In this function I am taking value passed in the body and simply pushing it into an existing array, I am not validating any values as of now but for the real application we should validate.

And after pushing it to the array I am simply sending a response with the updated values of an array.

So we are done with the logic of getter and setter methods, but still how to define routes?

For that we have to use Router class that we have imported at the very beginning of the post.

Using router I have defined get and post request with the name of routes(paths) and corresponding functions to be called when that route hits

Now to bind our router with our application we need to instantiate Application first and using .use method to set the middleware for router

The final step is to start the application with the listen method of the Application class

To run this code we need to fire following command

Note: As you can see i have put --allow-net which is mandatory in Deno.

Now we can test our API in Postman or Insomnia

GET Request

POST request

That’s the end of this simple Deno app!

Happy Coding!!!

If you have not installed Deno yet you can find the guide here.