feat(patients): add API to fetch previously prescribed medicines

Overview

This MR introduces a new feature to retrieve previously prescribed medicines for a patient. This helps doctors quickly reference past prescriptions, avoid duplicate medicines, and improve treatment continuity.

What does this MR do and why?

Adds functionality to fetch a patient’s previous medicines.

Motivation: Helps reduce repeated prescriptions, ensures safer medication practices, improves patient history tracking, and enables faster medicine entry during consultations.

Approach: Introduced a new API endpoint /patients/{id}/previous-medicines that returns all past medicines for a given patient using patient medical history records.

Changes Made

• Added new route /patients/{id}/previous-medicines in patient_routes.py
• Added service method get_previous_medicines(patient_id) in patient_service.py
• Added Pydantic response model PreviousMedicinesResponse
• Updated database query to fetch medicines linked to patient history
• Structured API response to include medicine name, dosage, frequency, and prescription date

Technical Details

Database:

• Added optimized query to retrieve medicines based on patient_id
• Results sorted by prescription date (descending) to show most recent medicines first

Service Layer:

• Service returns structured medicine data including:
  • Medicine name
  • Dosage
  • Frequency
  • Date prescribed

API:

• GET endpoint implementation
• Requires valid patient ID
• Returns 404 if patient not found
• Returns structured response using Pydantic models

Type of Change

• 🐛 Bug fix
• ✨ New feature
• 💥 Breaking change
• 📝 Documentation update
• ♻️ Refactor
• ⚡ Performance improvement
• 🧪 Test update
• 🔧 Configuration change
• 🚨 Security fix
• 🗑️ Deprecation

Related Issues / References

Closes #57 (closed)

Screenshots or Screen Recordings

• Added API testing screenshot
• Verified endpoint response using test data

How to Validate Locally

Previous behaviour:

• No way to retrieve previously prescribed medicines for a patient.

Steps to test:

1. Start the backend server
2. Open API docs (/docs)
3. Call: GET /patients/{id}/previous-medicines
4. Provide a valid patient ID
5. Verify response returns previously prescribed medicines

New behaviour:

• System returns list of previous medicines with structured details
• Returns empty list if no previous medicines exist
• Returns 404 if patient does not exist

Testing Done

• Unit tests added/updated
• API endpoint tests passing

Test Cases Covered:

Scenario Expected Result Status Valid patient with history Returns medicine list ✅ Valid patient without history Returns empty list ✅ Invalid patient ID Returns 404 error ✅

Test Commands Run:

pytest pytest tests/test_api_v1/test_patient_routes.py -v pytest --cov=app

Code Quality Checklist

Code Standards

• Code follows project conventions
• No debug statements left
• No unused imports
• No duplicate code
• Type hints properly defined
• Ruff checks pass

Python & FastAPI Best Practices

• Functions follow single responsibility
• Async/await used correctly
• Pydantic models used for validation
• SQLAlchemy queries optimized
• Error handling implemented

API Design

• RESTful conventions followed
• Proper HTTP status codes returned
• Input validation implemented
• Authentication enforced
• Role based access implemented
• API documentation updated

Database & Migrations

• No schema changes required
• No raw SQL used
• Data integrity maintained

Security

• No sensitive data logged
• SQL injection prevention verified
• Input sanitization handled

Error Handling

• Errors handled gracefully
• Proper error messages returned
• Errors logged appropriately

Documentation

• README updated
• .env.example updated
• API documentation updated
• CHANGELOG update pending
• Code comments added where needed

Known Limitations / Technical Debt

• Currently returns complete medicine history without filtering options
• Future improvement could include:
  • Pagination
  • Date filtering
  • Medicine search

Additional Notes

This feature improves patient consultation workflow by allowing doctors to quickly reference past prescriptions. No existing functionality was modified.

MR Acceptance Checklist

Quality & Correctness

• Code works as intended
• No existing functionality broken
• Edge cases handled

Maintainability

• Code is readable
• Additional automated tests can be added
• Follows project conventions

Acceptance Review

• Reviewed by teammate
• Product owner review pending