[FEAT] Implement API Endpoint for Sending Email Requests

[PcNerd9]

Description

Develop an endpoint to handle requests for sending emails using pre-defined templates. The emails should be placed in a database queue for sending to ensure the application remains responsive. The endpoint should handle variable substitution, replacing placeholders in the templates with actual data.

Acceptance Criteria

• The endpoint should receive requests to send emails using specific templates.
• The endpoint should handle variable substitution to replace placeholders with actual data.
• The email sending request should be stored in a database queue.
• The endpoint should return appropriate status codes and responses based on the outcome of the request.
• Endpoints should be correctly versioned.

Data Validation

• Input Validation: Validate that template_id, recipient, and variables fields are provided and correctly formatted.
• Output Validation: Ensure the response contains the correct status and message.

Authentication and Authorization

• Authentication: Ensure the endpoint requires valid user authentication.
• Authorization: Verify that the user has permission to send emails using the specified template.

  Error Handling

• Error Responses: Define error responses for scenarios such as missing template, invalid input, and internal server errors.
• Edge Cases: Consider edge cases such as template not found, invalid email format, and missing variables.

Performance and Security

• Performance Considerations: Ensure the email request queuing system is efficient and does not degrade application performance.
• Security Concerns: Address security considerations such as data sanitization, input validation, and protection against injection attacks.

Documentation

• API Documentation: Provide comprehensive API documentation for the endpoint, including request and response formats.
• Technical Notes: Include any additional technical notes or considerations for implementing the endpoint.

Testing Requirements

• Unit Tests: Implement unit tests to verify the functionality of the endpoint.
• Integration Tests: Develop integration tests to ensure the endpoint works correctly with other system components.

Dependencies and Impact

• Dependencies: Identify any dependencies on other tasks or systems, such as the database queue implementation.
• Impact Analysis: Assess the potential impact on other features or components of the application.

Requirements

• Implement an API endpoint for sending emails using templates.
• Handle variable substitution for placeholders in the email templates.
• Store email sending requests in a database queue.
• Handle unexpected errors and return the appropriate status codes.
• Ensure endpoints are correctly versioned.

Expected Outcome

• Users should be able to send requests to the backend to enqueue emails using templates.
• Users should receive appropriate status codes and responses based on the outcome of the requests.
• Emails should be queued for sending without blocking the main application flow.

Endpoints

[POST] /api/v1/send-email

• Description: Enqueues an email request using a specified template.
• Request Body:

  {
  "template_id": 1,
  "recipient": "john.doe@example.com",
  "variables": {
    "name": "John Doe",
    "product": "Wireless Headphones",
    "order_number": 12345
  }
  }
  **Success Response:**
  *Status Code: `202 Accepted`*
  *Body:*
  ```json
  {
  "message": "Email sending request accepted and is being processed in the background."
  }

  Error Responses: Status Code: 500 Internal Server Error Body:

  {
  "error": "Internal server error."
  }

status Code: 404 Not Found Body:

{
  "error": "Template not found."
}

Status Code: 405 Method Not Allowed Body:

{
  "error": "This method is not allowed."
}

Status Code: 400 Bad Request Body:

{
  "error": "An invalid request was sent."
}

Testing

Test Scenarios

1. Successful Email Sending Request

   • Ensure that the endpoint accepts a request to send an email using a template.
   • Verify that the response indicates the request is being processed in the background.
   • Confirm that the status code is 202 Accepted.

2. Template Not Found

   • Simulate a scenario where the specified email template ID does not exist.
   • Confirm that the response body contains an appropriate error message.
   • Confirm that the status code is 404 Not Found.

3. Internal Server Error

   • Simulate an internal server error to raise an exception.
   • Verify that the endpoint returns a 500 Internal Server Error status code.
   • Confirm that the response body contains an appropriate error message.

4. Invalid Method

   • Send a request using an invalid HTTP method (e.g., GET) to the endpoint.
   • Verify that the endpoint returns a 405 Method Not Allowed status code.
   • Confirm that the response body contains an appropriate error message.

5. Bad Request

   • Send a request with invalid data (e.g., missing required fields) to the endpoint.
   • Verify that the endpoint returns a 400 Bad Request status code.
   • Confirm that the response body contains an appropriate error message.

LINKS

link to the issue that implement the sending of the email in the background using Celery and RabbitMq https://github.com/hngprojects/hng_boilerplate_nestjs/issues/254#issue-2418183784

[markessien]

Appears VERY duplicated

[PcNerd9]

you commented on the previous issue created for this feature that the issue should be divided into two:

1. The email is placed in a db queue for sending
2. The email is retrieved from queue and dispatched. So that's issue was closed and i created two new issues to fit this requirements. One of the issues is this issue. I had gone through all the issues that's been created and accepted before creating this issue to avoid duplicate. In short, this issue is not a duplicate sir

[highb33kay]

Can you link both issues and I will review asap

[PcNerd9]

https://github.com/hngprojects/hng_boilerplate_nestjs/issues/254#issue-2418183784

link to the issue that implement the sending of the email in the background using Celery and RabbitMq

[highb33kay]

I have seen both. Can you explain the difference because I dont see it? @PcNerd9

[PcNerd9]

The simple explanation of the first issue:

• It retrieve the email template from the db
• Parse the email template by doing variable substitution
• Save the email request in the db queue

Simple explanation of the second issue:

• Write Celery Code that actually sends the email using a particular email service
• Celery fetches the request from the db queue using rabbitMQ
• Celery process the request in the background

Below is the link of the original issue where mark commented on saying that i should split into two tickets. https://github.com/hngprojects/hng_boilerplate_nestjs/issues/242#issue-2417496562 Hope this answer your question sir @highb33kay