Backend and domain / 2025

Scheduling API

Delivery scheduling is more than storing dates: availability, permissions and conflicts in a Go API.

context: API project, public code
role: Go API development
state: Prototype; build blocked
stack: Go / Gin / GORM / PostgreSQL

what it is

The API models appointments between suppliers and employees. The repository contains JWT authentication, operation and product models, validation services and GORM queries.

the problem

Accepting a delivery requires checking entities, operating hours and overlaps in both employee and supplier schedules. An isolated availability query does not guarantee exclusivity under concurrency.

the constraints

Validation before writing: The service checks entities and hours; the repository checks conflicts before creating an appointment.
Two calendars: HasConflict queries employees and suppliers, ignoring cancelled appointments.

the architecture

Layers identifiable in the prototype code.

HTTP
internal/api
Gin, handlers and JWT/RBAC middleware.
Service
internal/service
Entities, operating hours and appointment state.
Repository
internal/repository
Conflict queries and GORM writes.
Domain
internal/models
Appointment, employee, supplier and operation.

This is a code map, not evidence of a production service. Files contain truncated sections and the clone does not build.

technical decisions

Separate transport, rules and data
why
Handlers delegate to the service; queries live in the repository. This makes each validation location explicit.
instead of
Keeping data access and rules in HTTP handlers.
the price
The separation has no tests protecting its contracts yet.
Query conflicts before inserting
why
HasConflict queries overlaps without loading the entire schedule into memory.
instead of
Enforcing exclusivity through a PostgreSQL exclusion constraint.
the price
The check precedes the write transaction. Concurrent requests can pass the same check.

limits and lessons

The clone does not build

go.sum contains invalid comments. Repository and service files also contain truncated sections and duplicate declarations. The first build error is transcribed below.

Untested rule

There are no _test.go files. The central rule needs cases for boundaries, overlap, cancellation and concurrency.

current state

The available artifact is a backend prototype and its domain model. There is no deployment, usage or performance evidence. Review on 1 October 2026 reproduced the initial build failure.

next questions

Restore files and go.sum before expanding the domain.
Test intervals and concurrency; evaluate database-level overlap exclusion.

evidence

go build ./... · 2026-10-01state

malformed go.sum:
go.sum:1: wrong number of fields 7

Clone output; absolute path omitted. No source files were repaired during this audit.

internal/repository/appointment_repository.go

hasConflict, err := r.HasConflict(appointment)
// ...
err = r.db.Transaction(func(tx *gorm.DB) error {
    if err := tx.Create(appointment).Error; err != nil {
        return err
    }
    return nil
})

Create excerpt: the conflict query precedes the transaction. These calls are an excerpt, not a complete file.

sources and review

Code reviewed on 2026-10-01

Scheduling API@1b54796

next: PsyPredict