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Backend Overview

Role of the backend​

The backend is the coordination layer of the system. It is responsible for turning user actions into validated business operations.

Its responsibilities include:

  • user session and identity integration;
  • project creation and membership management;
  • requisition workflow orchestration;
  • database persistence;
  • Snipe-IT integration;
  • audit trail creation;
  • authorization enforcement.

Technology baseline​

The current technology direction uses:

  • FastAPI as the API framework;
  • SQLModel / SQLAlchemy-based persistence for database interaction;
  • PostgreSQL for application-domain persistence.

Why this backend shape is appropriate​

This project needs a backend that is:

  • API-first;
  • suitable for both web and mobile clients;
  • easy to validate and document;
  • practical for integration with external services.

FastAPI is well suited to this style because it supports strongly typed request/response definitions and automatic API documentation.

Logical backend layers​

A clean backend structure should separate:

API layer​

Responsible for request parsing, response models, and route definitions.

Service layer​

Responsible for workflow and business rules, such as:

  • validating project membership;
  • deciding if a request can move to the next status;
  • coordinating assignment and return operations.

Integration layer​

Responsible for external service communication, especially:

  • Snipe-IT API access;
  • authentication-provider interaction.

Persistence layer​

Responsible for repositories, ORM models, and transactions.

Design recommendation​

Do not place business rules directly in route handlers. Route handlers should stay thin and delegate to service logic.

Typical backend responsibilities by use case​

Use caseBackend responsibilities
Create projectvalidate input, create records, assign creator, set initial status
Submit requisitionvalidate project context, create request header and items
Approve requestauthorize technician action, update status, record history
Assign equipmentreconcile request items with available inventory assets
Return equipmentclose usage records, update state, preserve history