Simple Bank Account

A simple REST microservice that can create a customer and customer account. A customer can have multiple bank accounts and multiple Debit/Credit card numbers. The service supports account top-ups and account withdrawal functions.

Key Objectives

• Creating a new customer
• Creating a new customer account
• Ability to perform a withdrawal and top up

Project Architecture & Design

• The service follows a Domain Driven approach. Throughout the application, we can generally come with certain bounded contexts: (1) A Customer, whose main responsibility is to represent a real world customer, capable of making bank withdrawals and deposits (2) A Customer Account whose responsibility is to represent a customer's bank account details and status (3) A Customer Card whose main responsibility is to represent a customer's bank cards
• The service uses a PostgreSQL database for data persistence and has three tables (entities): (1) customer table (2) customer_account table (3) customer_card table
• The relationship between the three entities is as shown below:

Process flows

1. Customer Creation Process

2. Account Creation Process

3. Account Withdrawal Process

4. Account Top-up Process

• More details of the service architecture and design can be found in the design document

Installation, Building & Testing

1. Cloning

Let's start by getting the application from Github to our local machine.

git clone https://github.com/gillerick/simple-bank-account

2. Configuring

A configuration file already exists under the root path of the application. Its structure is shown below. Also, we have made the provision to set the properties as envs. Go over to configs/yaml.go file to see this.

app:
  host: "app-host"
  port: "app-port"
database:
  user: "db-user"
  password: "db-password"
  host: "db-host"
  port: "db-port"
  dbname: "db-name"

3. Starting Docker compose

Run the command below to set up the dependencies and database.

$ docker-compose up

4. Running the application

make run

If you see the logs below, your Simple Bank Account service was successfully set up.

INFO[0000] running db migrations                         source="migrations.go:10"
INFO[0000] db migrations ran successfully                source="migrations.go:17"
INFO[0000] server listening on address: 127.0.0.1, port: 8080  source="server.go:23"

API Usage

A description of the API and endpoints can be found in the design documentation under API section.

1. Creating a customer

Curl request example

curl --location --request POST 'http://localhost:8080/user' \
--header 'Content-Type: application/json' \
--data-raw '{
    "first_name": "Gill",
    "last_name": "Erick",
    "email": "[email protected]"
}'

Response example

{
  "user_id": "54b819af-bc4d-442d-a361-a917adb6173a",
  "first_name": "Gill",
  "last_name": "Erick",
  "email": "[email protected]",
  "Accounts": null,
  "Cards": null,
  "CreatedAt": "2022-11-14T22:33:48.794892+03:00",
  "UpdatedAt": "2022-11-14T22:33:48.794892+03:00",
  "DeletedAt": null
}

Database record(s)

+------------------------------------+----------+---------+---------------------+--+---------------------------------+---------------------------------+----------+
|user_id                             |first_name|last_name|email                |id|created_at                       |updated_at                       |deleted_at|
+------------------------------------+----------+---------+---------------------+--+---------------------------------+---------------------------------+----------+
|54b819af-bc4d-442d-a361-a917adb6173a|Gill      |Erick    |[email protected]|1 |2022-11-14 19:33:48.794892 +00:00|2022-11-14 19:33:48.794892 +00:00|null      |
+------------------------------------+----------+---------+---------------------+--+---------------------------------+---------------------------------+----------+

2. Creating a customer account

2.1. CURRENT account type creation

Request example

curl --location --request POST 'http://localhost:8080/user/54b819af-bc4d-442d-a361-a917adb6173a/account' \
--data-raw '{
    "account_type":"CURRENT"
}'

Response example

{
  "account_type": "CURRENT",
  "Status": "ACTIVE",
  "AvailableBalance": 0,
  "UserId": "43e81839-a159-4979-badf-cd0a96e3473c",
  "CreatedAt": "2022-11-14T22:55:46.292318+03:00",
  "UpdatedAt": "2022-11-14T22:55:46.292318+03:00",
  "DeletedAt": null
}

2.2. SAVINGS account type creation

Request example

curl --location --request POST 'http://localhost:8080/user/54b819af-bc4d-442d-a361-a917adb6173a/account' \
--header 'Content-Type: application/json' \
--data-raw '{
    "account_type":"SAVINGS"
}'

Response example

{
  "account_type": "SAVINGS",
  "Status": "ACTIVE",
  "AvailableBalance": 0,
  "UserId": "54b819af-bc4d-442d-a361-a917adb6173a",
  "ID": 2,
  "CreatedAt": "2022-11-14T23:17:13.975603+03:00",
  "UpdatedAt": "2022-11-14T23:17:13.975603+03:00",
  "DeletedAt": null
}

2.3. Attempting to create a repeat account

Request example

curl --location --request POST 'http://localhost:8080/user/54b819af-bc4d-442d-a361-a917adb6173a/account' \
--header 'Content-Type: application/json' \
--data-raw '{
    "account_type":"SAVINGS"
}'

This will return with the current SAVINGS account for user 54b819af-bc4d-442d-a361-a917adb6173a with no additional account created in the database.

Database records(s)

+-------+------+-----------------+------------------------------------+--+---------------------------------+---------------------------------+----------+
|type   |status|available_balance|user_id                             |id|created_at                       |updated_at                       |deleted_at|
+-------+------+-----------------+------------------------------------+--+---------------------------------+---------------------------------+----------+
|SAVINGS|ACTIVE|0                |54b819af-bc4d-442d-a361-a917adb6173a|2 |2022-11-14 20:17:13.975603 +00:00|2022-11-14 20:17:13.975603 +00:00|null      |
|CURRENT|ACTIVE|0                |54b819af-bc4d-442d-a361-a917adb6173a|3 |2022-11-14 20:17:27.548399 +00:00|2022-11-14 20:17:27.548399 +00:00|null      |
+-------+------+-----------------+------------------------------------+--+---------------------------------+---------------------------------+----------+