Developer GuideΒΆ

This document focuses frontend and backend development of Purpie project and gives information about Purpie Tech Stack.



  • Node.js. (>= 10.13.0, except for v13) (Windows Build Tools for Windows systems)

  • Yarn.

Clone RepositoryΒΆ

git clone
cd purpie

Install dependenciesΒΆ

yarn install

Set environment variables into .env file:ΒΆ

cp .env.example .env

Then make changes to the boilerplate provided

Setting web server and routingΒΆ

If Purpie is installed on your local computer, you will need to add the following line to your hosts file. The hosts file for Unix based system including MacOs is /etc/hosts where as on Windows, it is C:\windows\system32\drivers\etc\hosts.      purpie.localhost

Run projectΒΆ

yarn start

Try PurpieΒΆ



First steps are same with fronted setup.

Create Postgres databaseΒΆ

Please follow the steps below to get a development Postgres server running. The easiest way to use docker. If you have running Postgres database server you can skip these steps and simply create an Purpie database.

  • Make sure you have docker installed on your computer. If you do not have docker already on your computer, Go to, choose your platform and click download. Follow the simple steps to get docker installed on your computer.

  • Open your terminal (command prompt or preferably powershell on windows).

  • Enter the command

docker run --name purpie-postgres-dev -e POSTGRES_PASSWORD=YOUR_DB_PASSWORD -p 5432:5432 -d postgres
  • Postgres docker image will be downloaded and Postgres Docker container with the name purpie-postgres-dev will up and serve from port 5432 after this command.

  • To connect your Postgres database.

docker exec -it purpie-postgres-dev psql -U postgres
  • To create your Purpie database.

  • Update your .env file with YOUR_DB_PASSWORD .

  • Run \q to quit from Psql and Docker container.

Run projectΒΆ

To run backend server in production

yarn start:server

To run backend server in development

yarn start:server:dev

API TestingΒΆ

Visit http://purpie.localhost:8000/swagger/ to try out some backend APIs.

Software SpecΒΆ

Frontend FeaturesΒΆ

Backend FeaturesΒΆ

Open Source Technologies usedΒΆ



  • 🏠 represents client side

  • πŸ–₯️ represents server side


This is a single page web application, that is it handles routing at the client-side without the need to refresh the entire page. All http requests are done using Asynchronous Javascript and XML (AJAX). The data exchange format used between this app and the server is JSON.

Programming LanguagesΒΆ


HTML is rarely used in this app. It is primarily used to setup the main index file that is responsible for loading the main javasript of the app. It loads the css and display the initial title of the app.

TypeScript 🏠πŸ–₯️¢

This app uses no Javascript (Although it compiles to javascript). Typescript is the main programming language used on the server and for building the user interface.

Frameworks and LibrariesΒΆ

NestJS πŸ–₯️¢

Nestjs is a progressive Node.js framework for building efficient, reliable and scalable server-side applications. It works well with typescript and follows the SOLID principle

TypeORM πŸ–₯️¢

TypeORM is a NodeJS database ORM that supports the latest JavaScript features and provide additional features that helps in developing any kind of application that uses databases - from small applications with a few tables to large scale enterprise applications with multiple databases. It works well with typescript.

OpenAPI (Swagger) πŸ–₯️¢

The OpenAPI specification is a language-agnostic definition format used to describe RESTful APIs. Nest provides a dedicated module which allows generating such a specification by leveraging decorators.

Handlebars πŸ–₯️¢

Handlebars is used to render email templates before they are sent to clients.

SendGrid πŸ–₯️¢

SendGrid is the main service used for sending emails.

Class Validator πŸ–₯️¢

Allows use of decorator and non-decorator based validation. Internally uses validator.js to perform validation.

Axios 🏠πŸ–₯️¢

Axios is a promise based HTTP client used in this app. All AJAX requests are handled with axios. Their interceptors really help to avoid redundancy in most part of the app.


This app uses no CSS (Although it compiles to css in the long run). SCSS is rearely used in this app. It is used to style a large portion of the app. SCSS Modules is recommended if SCSS is used. node-sass is the library responsible for compiling the app’s scss to css

React 🏠¢

This app uses the latest version of React Framework (Library) in collaboration with Typescript. JavaScript XML is used to develop all the components. Only Functional Components are allowed for writing all React Components.

Grommet 🏠¢

Grommet is a React styled-component library that helps in building responsive and accessible mobile-first projects for the web. Since this framework provides lots of styled-components, writing scss is often not required at all. Developers are required to use most of the features of Grommet without writing lots of scss .

React Router DOM 🏠¢

React Router (Its DOM binding React Router DOM) is the library used to for handling all the client side routing of this app. Note that instead of using the library’s main Link and NavLink components, AnchorLink and NavLink are used respectively. This is to make it compatible with the Grommet library. To navigate to other paths of the app inside a component, the useHistory hook is used. Routing done in other parts of the app app (especially in a Redux action) uses the appHistory helper function insead.

Redux 🏠¢

Redux is a predictable state Container for Javascript (Typescript) Apps. This is the main state management library used in the app. Mostly states that are shared across multiple components of the app use redux. Also all network-related states are handled here. react-redux is the library that helps in binding redux to react. redux-thunk provides the redux middleware that helps the app to deal with asynchronous dispatches in redux actions.

React-i18next 🏠

React-i18next is a powerful internationalization framework for React / React Native which is based on i18next. Our goal is to support as many languages as possible with the help of this framework and community.

Development DependenciesΒΆ

Eslint 🏠πŸ–₯️¢

Eslint statically analyzes the application code to quickly find problems. It helps in maintaining the usage of Airbnb coding style guide and the similarity of code written by different develops at a time. Run yarn analyze or npm analyze to let eslint analyze and report all errors made. If you are using editors like vscode please install the eslint extension to help you in automatically detecting errors.

Prettier 🏠πŸ–₯️¢

Prettier is an opinionated code formatter that helps the app to format the code written to comform to the rules of eslint. Run yarn format or npm format to do a quick format of the entire app.

Jest 🏠πŸ–₯️¢

Jest is a delightful JavaScript Testing Framework with a focus on simplicity.

NestJS πŸ–₯️¢

While using nestjs at the server-side, One must follow these guidelines.

  • NestJS pattern must be followed strictly. For example controllers should be used to handle only http requests, services must be used to generate data or communicate with the database, guards must be used for securing routes etc.

  • controllers and providers should reside in controllers and services directories respectively.

  • Implement global providers if they are needed only. This will help other developers know from which modules those services are imported from. Example authentication and exceptions would be needed in the entire application but zone service wouldn’t.

  • the @IsAuthenticated() decorator should be used to validate the current user’s token. Also permissions could be passed in as paremeters if they are needed.

  • Document the controllers written extensively (using decorators provided by Nestjs for OpenAPI). This helps other developers to make requests very easily without reading the source code.

  • The built in NestJS exceptions must be used accross the entire application. The first paramter must be a message about the error. And the second parameter must be an error code. For example while generating an error for invalid bearer authentication token, the example below is used.

throw new UnauthorizedException(
      'You not authorized to use this route',

TypeORM πŸ–₯️¢

While using TypeORM at the server-side, One must follow these guidelines.

  • The models designed must be relational. That means you must use OneToOne, ManyToOne, OneToMany or ManyToMany relation when it is necessary.

  • When models, fields, column, etc. are added a migration script must be written in respect of that. This is because we are not using syncronization as it not good for production. Note that nestjs will run pending migrations when the application is booted automatically.

Guards In This Application and their usageΒΆ

This section introduces the main guards used in this application

  • AuthGuard

    The AuthGuard validates the current bearer token passed to the server when making requests. It sets the payload of the user to req.user. It also thows an UnauthorizedException exception when the token is invalid.

  • UserZoneGuard

    The UserZoneGuard validates the current user’s authorization to the zone that he/she is requesting. It sets the user zone to req.userZone. Other permissions can be passed in using the SetMetadata decorator. It also throws an NotFoundException exception when the user is not authorized.

Pipes in this application and their usageΒΆ

This section introduces the main pipes used in this application

  • ParseTokenPipe

    The ParseTokenPipe is used to parse a JWT. If it succeeds it passes the payload to the parameter. Otherwise it will throw an UnauthorizedException.

Decorators in this application and their usageΒΆ

This section introduces the main decorators used in this application

  • IsAuthenticated

    The IsAuthenticated decorator wraps over the AuthGuard to avoid writing lots of boilerplates while passing permissions to the AuthGuard.

  • UserZoneRole

    The UserZoneRole decorator wraps over the UserZoneGuard to avoid writing lots of boilerplates while passing permissions to the it. It also extends the IsAuthenticated decorators so if you do not need to specify it while using it on a route.

  • UserChannelRole

    The UserZoneRole decorator wraps over the UserChannelGuard to avoid writing lots of boilerplates while passing permissions to the it. It also extends the IsAuthenticated decorators so if you do not need to specify it while using it on a route.

  • CurrentUser

    The CurrentUser decorator is helper to retrieve the current user’s jwt payload

  • CurrentUserZone

    The CurrentUserZone decorator is helper to retrieve the current user zone. Notice that it zoneId or userZoneId must be set as params in order to retrieve this.

  • CurrentUserChannel

    The CurrentUserChannel decorator is helper to retrieve the current user channel. Notice that it channelId or userChannelId must be set as params in order to retrieve this.

Middlewares Used in this applicationΒΆ

This section introduces the main middlewares used in this application.

  • PaginationMiddleware

    The PaginationMiddleware parses all get requests’ pagination query paramters. All get requests pass through this middleware. This means that, the pagination query parameters req.query.limit and req.query.skip are passed to controllers automatically (Global middleware for get requests). It can in turn be used in paginating records. When no values for limit and skip query parameters are passed by the user, limit is set to a default of 30 and skip is also set to a default of 0. Limit cannot be greater that 100. The type PaginationQuery can help in intellisense.


This app interacts with a stateless http server. Authentication is realized by sending a JSON Web Token (By the way this is one of my favorite technologies) to the server. The steps for authenticating users are listed below.

  1. When it is the first time the user is visiting the app or the returning user is not authenticated, React Router will redirect the user to the login page.

  2. The User will either login or create a new account

  3. The app sends the authentication information to the server

  4. If the server successfully authenticates the user, a json web access token and its refresh token is created on the server and sent as an http only cookie to the client

  5. By default the access token only lasts an hour. After this if the refresh token is still valid, the server will generate a new access and refresh tokens to the client

  6. In subsequent requests, the app will send the access token stored in the cookies to the server to identify the user making the request.

  7. If the token expires or becomes invalid the user will automatically be redirected to the login page. Thanks to the axios response interceptor.

  8. If the user returning to the app is already authenticated react router will redirect the user to the main application page.

Authentication persistence through subdomainsΒΆ

Since this app allows users to create subdomains, it needs to persist authentication through the main domain and subdomains. This is one of the main reasons why cookies are been used. For cookies to persist authentication through domains and subdomains, the main domain parameter supplied while creating them must be valid. One of the rules for its validity is that it must have at least one dot. Due to this, localhost will not work. Read this article to learn more. Even though developers can still use localhost but if another subdomain is visited, authentication would be required again. Developers can therefore set a different domain other than localhost in /etc/host ( or C:\Windows\System32\Drivers\etc\hosts for windows) file. The domain recommended is octopus.localhost. This is because it allows all subdomains to see the cookie as well. # Application Structure

β”œβ”€β”€ appspec.yml
β”œβ”€β”€ package-lock.json
β”œβ”€β”€ package.json
β”œβ”€β”€ scripts
β”‚Β Β  β”œβ”€β”€
β”‚Β Β  β”œβ”€β”€
β”‚Β Β  └──
β”œβ”€β”€ server
β”‚   β”œβ”€β”€
β”‚   β”œβ”€β”€ dist
β”‚   β”œβ”€β”€ entities
β”‚   β”‚   β”œβ”€β”€ Channel.entity.ts
β”‚   β”‚   β”œβ”€β”€ Invitation.entity.ts
β”‚   β”‚   β”œβ”€β”€ Post.entity.ts
β”‚   β”‚   β”œβ”€β”€ User.entity.ts
β”‚   β”‚   β”œβ”€β”€ UserChannel.entity.ts
β”‚   β”‚   β”œβ”€β”€ UserChannelPermission.entity.ts
β”‚   β”‚   β”œβ”€β”€ UserZone.entity.ts
β”‚   β”‚   β”œβ”€β”€ UserZonePermission.entity.ts
β”‚   β”‚   β”œβ”€β”€ Zone.entity.ts
β”‚   β”‚   β”œβ”€β”€ base
β”‚   β”‚   β”œβ”€β”€ data
β”‚   β”‚   └── repositories
β”‚   β”œβ”€β”€ helpers
β”‚   β”‚   β”œβ”€β”€ jwt.ts
β”‚   β”‚   └── utils.ts
β”‚   β”œβ”€β”€ migrations
β”‚   β”‚   └── 1625561314952-InitialMigration.ts
β”‚   β”œβ”€β”€ ormconfig.ts
β”‚   β”œβ”€β”€ src
β”‚   β”‚   β”œβ”€β”€ app.module.ts
β”‚   β”‚   β”œβ”€β”€ auth
β”‚   β”‚   β”œβ”€β”€ mail
β”‚   β”‚   β”œβ”€β”€ main.ts
β”‚   β”‚   β”œβ”€β”€ typeorm-exception.filter.ts
β”‚   β”‚   β”œβ”€β”€ utils
β”‚   β”‚   β”œβ”€β”€ views
β”‚   β”‚   └── zone
β”‚   β”œβ”€β”€ test
β”‚   β”‚   β”œβ”€β”€ app.e2e-spec.d.ts
β”‚   β”‚   β”œβ”€β”€ app.e2e-spec.js
β”‚   β”‚   β”œβ”€β”€
β”‚   β”‚   β”œβ”€β”€ app.e2e-spec.ts
β”‚   β”‚   └── jest-e2e.json
β”‚   β”œβ”€β”€
β”‚   β”œβ”€β”€ tsconfig.json
β”‚   β”œβ”€β”€ tsconfig.tsbuildinfo
β”‚   └── types
β”‚       β”œβ”€β”€ Post.ts
β”‚       β”œβ”€β”€ PaginationQuery.ts
β”‚       β”œβ”€β”€ UserPayloadRequest.ts
β”‚       └── UserZoneRequest.ts
β”œβ”€β”€ src
β”‚Β Β  β”œβ”€β”€ App.tsx
β”‚Β Β  β”œβ”€β”€ assets
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ background.png
β”‚Β Β  β”‚Β Β  └── logo.png
β”‚Β Β  β”œβ”€β”€ components
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ layouts
β”‚Β Β  β”‚Β Β  └── utils
β”‚Β Β  β”œβ”€β”€ config
        β”‚   └── [language].json
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ app-config.ts
β”‚Β Β  β”‚Β Β  └── http.ts
β”‚Β Β  β”œβ”€β”€ helpers
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ history.ts
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ utils.ts
β”‚Β Β  β”‚Β Β  └── validators.ts
β”‚Β Β  β”œβ”€β”€ hooks
β”‚Β Β  β”‚Β Β  └── useTitle.ts
β”‚Β Β  β”œβ”€β”€ index.tsx
β”‚Β Β  β”œβ”€β”€ layers
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ meeting
β”‚Β Β  β”‚Β Β  └── zone
β”‚Β Β  β”œβ”€β”€ models
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ form-submit-event.ts
β”‚Β Β  β”‚Β Β  └── response-error.ts
β”‚Β Β  β”œβ”€β”€ pages
β”‚Β Β  β”‚Β Β  β”œβ”€β”€ Private
β”‚Β Β  β”‚Β Β  └── Public
β”‚Β Β  β”œβ”€β”€ react-app-env.d.ts
β”‚Β Β  β”œβ”€β”€ routes.ts
β”‚Β Β  β”œβ”€β”€ scss
β”‚Β Β  β”‚Β Β  └── index.scss
β”‚Β Β  └── store
β”‚Β Β      β”œβ”€β”€ actions
β”‚Β Β      β”œβ”€β”€ constants
β”‚Β Β      β”œβ”€β”€ reducers
β”‚Β Β      β”œβ”€β”€ services
β”‚Β Β      β”œβ”€β”€ store.ts
β”‚Β Β      └── types
└── tsconfig.json

    This is the main readme file of the application

  • package-lock.json

    This is automatically generated for any operations where npm modifies either the node_modules tree, or package.json. It describes the exact tree that was generated, such that subsequent installs are able to generate identical trees, regardless of intermediate dependency updates.

  • package.json

    Lists all the dependencies, author, version, etc of the app.

  • public

    This is where the main index.html file that loads the react app lives.

  • server

    This is where most backend work is done in this app.

    • dist

      Typescript compiles to this directory.

    • entities

      This is directory hosts all the typeorm model definitions. All typeorm entities must end with .entity.ts

      • base

        This directory hosts the typeorm models that will be inherited by other models. For example the RecordEntity defines most of the repeating fields in records such as id, createdOn, updatedOn etc.

      • data

        This directory hosts the default data used by some entities.

    • helpers

      This directory hosts all the utilities functions of the application.

    • migrations

      This directory hosts all the migration scripts used by typeorm. To create a new migration please use the script yarn migration:create. NestJS automatically runs all pending migrations when it is booted. While creating migrations, typeorm driver must be prefered to raw sql. This helps in migrating to other databases in the future.

    • types

      This directory hosts all the utility typescript types used in the application.

    • test

      This is the directory that hosts all end-to-end testing scripts.

    • src

      This is the directory where most of the work is done. It hosts all the NestJS controllers, modules, services, pipes, guards, middlewares etc. Note that, scripts other than NestJS specific shouldn’t be put here.

      • app.module.ts

        The root module of the application. All other modules are imported into this file.

      • main.ts

        The entry file of the application which uses the core function NestFactory to create a Nest application instance.

      • mail

        This directory hosts the module used for sending mails in this application. To send a mail, a view is created inside the views directory. The MailModule is imported into the current module and the MailService is injected into the current service. Using the sendMailByView method of the mail service emails can be sent using sendgrid.

      • [module_name]

        The src directory hosts all the nestjs modules in this application. To create a new module, a new directory with the same name is created. It is recommended that the nest cli is used to generate modules, controllers, services etc. The nest cli command nest g module [module_name] generates a new module. This creates a new directory inside the src folder and a new module named [module_name].module.ts. All directories created inside this must not be empty.

        • decorators

          All decorators for this module is created in this directory.

        • dto

          All dtos for this module is created in this directory. A DTO is an object that defines how the data will be sent over the network. This is especially useful in POST and PUT requests. The class validator decorators can also help in validating payload fields. All dtos must end with .dto.ts.

        • pipes

          All pipes for this module is created in this directory. Pipes are used to transform input data coming from req.body, req.query or req.params etc. All pipes must end with .pipe.ts

        • guards

          All guards for this module is created in this directory. Guards determine whether a given request will be handled by the route handler or not, depending on certain conditions (like permissions, roles, ACLs, etc.) present at run-time. All guards must end with .guard.ts

        • interfaces

          All interfaces for this module is created in this directory. Note: All interface must be declared using class but not the interface keyword. This is because Typescript removes all interfaces when it is compiling to Javascript. All interfaces must end with .interface.ts

        • exceptions

          All exceptions for this module is created in this directory. Nest comes with a built-in exceptions layer which is responsible for processing all unhandled exceptions across an application. When an exception is not handled by your application code, it is caught by this layer, which then automatically sends an appropriate user-friendly response. All exceptions must end with .exception.ts

        • controllers

        If multiple controllers are used in this module, it is recommended to put them in the controllers directory. Otherwise there is no need to create this directory for them. All controllers must end with .controller.ts

        • controllers

        If multiple services are used in this module, it is recommended to put them in the services directory. Otherwise there is no need to create this directory for them. All services must end with .service.ts


        This is the file that all providers, controllers etc of this module are imported into. This is then imported into the app.module.ts

    • ormconfig.ts

      This is the file that contains all the configuration of the application’s database. It is used by typeorm to create migrations and connect to the database.

    • tsconfig.json

      This is the file that contains the typescript configuration for the server. The configuration used in this app is in strict mode.

  • src

    This is where most frontend work is done in this app.

    • App.tsx

      This is the main component that loads the app routes and run initial scripts (eg. retrieving current user)

    • assets

      This directory contains all the static assests used in the app

    • components

      This directory contains most of the helper components used in the app

    • config

      This directory contains all the configuration files of the app

    • helpers

      This directory contains all the utilities functions of the app

    • hooks

      This directory contains all the general react hooks used in the app

    • index.tsx

      This is the main script and starting point of the app responsible for bootstrapping the react app

    • layers

      This is the directory where layers (modals) used in the app are stored

    • models

      This is the directory where typescript types used accross the entire app are declared.

    • pages

      This is the directory where pages served in the browser are stored

      • Private

        All Privates Pages are stored in this directory.

      • Public

        All Public Pages are stored in this directory.

    • react-app-env.d.ts

      This is a generated file coming with create react app

    • routes.ts

      This is the file where all public and private routes are decalared. All public and private routes live in the publicRoutes and privateRoutes array respectively. Make sure you put the route in the correct context. All private routes require that users are authenticated, otherwise they will be redirected to the login page

    • scss

      The directory that hosts all the scss for the app

    • store

      This is the directory that is used to handle everything to do with the app’s redux store.

      • actions

        All actions of the store are declared in this directory. Every action ends with .action.ts. This is to make all actions easier to search. Also all action functions end with Action.

      • constants

        All constants used in the store is declared in this directory. End all constants with .constant.ts. This is to make all constants easier to search.

      • reducers

        All reducers of the store are declared in this directory. Every reducer ends with .reducer.ts. This is to make all reducers easier to search.

      • services

        All services of the store are declared in this directory. Every service ends with .service.ts. This is to make all services easier to search. The http helper function must be used to make http requests

      • store.ts

        This is the script that creates the main store of the app.

      • types

        All typescript types of the stored are declared in this directory. Every type file ends with .types.ts. This is to make all types easier to search.

      • tsconfig.json

        This is the file that contains the typescript configuration for the app. The configuration used in this app is strict

    • scripts

      Server run and build commands are included in this folder files for installing requirements and ci cd auto deployment.

    • appspec.js

      file contains scripts files calls for ci cd auto deployment into aws instance