Expense Tracking App

Implementing a Expense Tracking App for Capstone project of https://www.udacity.com/course/cloud-developer-nanodegree--nd9990

Functionality of the application

This application will allow creating/removing/updating/fetching (CRUD) Expenses.

The application stores Expense items, and each Expense item contains the following fields:

expenseId (string) - a unique id for an item
userId (string) - a unique id for the user who created it
date (string) - date and time when an item was created or updated
name (string) - name of a Expense item (e.g. "Shopping Mall bill")
description (string) - description of the bill (e.g. "shirts for friends")
amount (float) - amount of the bill

In this project, auth is configured in serverless.yml file:

Auth - this function implements a custom authorizer for API Gateway and all lambda functions use it.
GetExpenses - returns all Expenses for a current user. A user id can be extracted from a JWT token that is sent by the postman

It returns data that looks like this:

{
  "expense": [
    {
      "amount": 190,
      "date": "2021-02-28T08:08:27.802Z",
      "description": "test expense2 - description- 1st account-1",
      "name": "test expense2 - 1st account1",
      "userId": "google-oauth2|115387772605073873555",
      "expenseId": "1c84526b-28c0-4f0c-ad6a-2ec7e3b9a7db"
    },
    {
      "amount": 45500.9,
      "date": "2021-02-28T08:09:15.341Z",
      "description": "test expense4 - description- 1st account-1",
      "name": "test expense4 - 1st account1",
      "userId": "google-oauth2|115387772605073873555",
      "expenseId": "29cdba07-8c7e-444f-8e34-0a5dc4bc8535"
    },
    {
      "amount": 90,
      "date": "2021-02-28T08:09:56.728Z",
      "description": "test expense - modified",
      "name": "test expense -- modified ",
      "userId": "google-oauth2|115387772605073873555",
      "expenseId": "3e90561d-d636-486c-8d6d-d43d32196608"
    }
  ]
}

CreateExpense - creates a new Expense for a current user. A shape of data send by a client application to this function can be found in the CreateExpenseRequest.ts file

{
  "name" : "test expense4 - 1st account1",
  "description" : "test expense4 - description- 1st account-1",
  "amount": 45500.90
}

It should return a new Expense item that looks like this:

{
  "expense": {
    "userId": "google-oauth2|115387772605073873555",
    "expenseId": "29cdba07-8c7e-444f-8e34-0a5dc4bc8535",
    "name": "test expense4 - 1st account1",
    "description": "test expense4 - description- 1st account-1",
    "date": "2021-02-28T08:09:15.341Z",
    "amount": 45500.9
  }
}

UpdateExpense - should update a Expense item created by a current user. A shape of data send by a client application to this function can be found in the UpdateExpenseRequest.ts file

It receives an object that contains three fields that can be updated in a TODO item:

{
  "name" : "test expense -- modified ",
  "description" : "test expense - modified",
  "amount" : 90
}

The id of an item that should be updated is passed as a URL parameter.

It should return the updated Expense item that looks like this:

{
  "expense": {
    "userId": "google-oauth2|115387772605073873555",
    "expenseId": "29cdba07-8c7e-444f-8e34-0a5dc4bc8535",
    "name": "test expense -- modified ",
    "description": "test expense - modified",
    "date": "2021-02-28T08:09:15.341Z",
    "amount": 90
  }
}

DeleteExpense - should delete a Expense item created by a current user. Expects an id of a Expense item to remove.

It should return an empty body.

All functions are connected to appropriate events from API Gateway.

An id of a user can be extracted from a JWT token passed by a client.

Authentication

To implement authentication, an Auth0 application was created and symmetrically encrypted JWT token is used

Database Schema

ExpensesTable:
  Type: AWS::DynamoDB::Table
  Properties:
    AttributeDefinitions:
      - AttributeName: userId
        AttributeType: S
      - AttributeName: expenseId
        AttributeType: S
      - AttributeName: createdAt
        AttributeType: S
    KeySchema:
      - AttributeName: userId
        KeyType: HASH
      - AttributeName: expenseId
        KeyType: RANGE
    BillingMode: PAY_PER_REQUEST
    TableName: ${self:provider.environment.EXPENSES_TABLE}
    LocalSecondaryIndexes:
      - IndexName: ${self:provider.environment.INDEX_NAME}
        KeySchema:
          - AttributeName: userId
            KeyType: HASH
          - AttributeName: createdAt
            KeyType: RANGE
        Projection:
          ProjectionType: ALL # What attributes will be copied to an index

How to run the application

Postman collection

You can use the Postman collection that contains sample requests. You can find a Postman collection in this project. To import this collection, do the following.