# Backend Dev Rules (HTTP API + Model)

This file condenses `backend/docs/dev/http_api.md` + `backend/docs/dev/model.md` into a checklist/rule format for LLMs.

---

## 0) Golden rules (DO / DO NOT)

- DO follow existing module layout under `backend/app/http/<module>/`.
- DO keep controller methods thin: parse/bind → call `services.*` → return result/error.
- DO regenerate code after changes (routes/docs/models).
- DO add `// @provider` above every controller/service `struct` declaration.
- DO keep HTTP middlewares in `backend/app/middlewares/` only.
- DO keep all `const` declarations in `backend/pkg/consts/` only (do not declare constants elsewhere).
- DO NOT manually edit generated files:
- `backend/app/http/**/routes.gen.go`
- `backend/app/http/**/provider.gen.go`
- `backend/docs/docs.go`
- DO NOT manually write provider declarations (only `atomctl gen provider`).
- DO NOT manually write route declarations (only `atomctl gen route`).
- DO keep Swagger annotations consistent with actual Fiber route paths (including `:param`).
- MUST: route path parameter placeholders MUST be `camelCase` (e.g. `:tenantCode`), never `snake_case` (e.g. `:tenant_code`).
- MUST: when creating/generating Go `struct` definitions (DTOs/requests/responses/etc.), add detailed per-field comments describing meaning, usage scenario, and validation/usage rules (do not rely on “self-explanatory” names).
- MUST: business code comments MUST be written in Chinese (中文注释), to keep review/maintenance consistent across the team.
- MUST: in `backend/app/services`, add Chinese comments at key steps to explain business intent and invariants (e.g., 事务边界、幂等语义、余额冻结/扣减/回滚、权限/前置条件校验点), avoid “what the code does” boilerplate.

---

## 1) Add a new HTTP API endpoint

### 1.1 Where code lives

- Controllers: `backend/app/http/<module>/*.go`
- Example module: `backend/app/http/super/tenant.go`, `backend/app/http/super/user.go`
- DTOs: `backend/app/http/<module>/dto/*`
- HTTP middlewares: `backend/app/middlewares/*`
- Routes (generated): `backend/app/http/<module>/routes.gen.go`
- Swagger output (generated): `backend/docs/swagger.yaml`, `backend/docs/swagger.json`, `backend/docs/docs.go`

### 1.2 Controller method signatures

- “Return data” endpoints: return `(<T>, error)`
- Example: `(*requests.Pager, error)` for paginated list
- “No data” endpoints: return `error`

### 1.3 Swagger annotations (minimum set)

Place above the handler function:

- `@Summary`
- `@Tags`
- `@Accept json`
- `@Produce json`
- `@Param` (query/path/body as needed)
- `@Success` for 200 responses
- `@Router <path> [get|post|patch|delete|put]`
- `@Bind` for parameters (see below)

Common `@Success` patterns:

- Paginated list: `requests.Pager{items=dto.Item}`
- Single object: `dto.Item`
- Array: `{array} dto.Item`

### 1.4 Parameter binding (@Bind)

Format:

`@Bind <paramName> <position> [key(<key>)] [model(<field>|<type>[:<field>])]`

Positions:

- `path`, `query`, `body`, `header`, `cookie`, `local`, `file`

Notes:

- `paramName` MUST match function parameter name (case-sensitive).
- Default key name is `paramName`                                               ; override via `key(...)`.
- Scalar types: `string/int/int32/int64/float32/float64/bool`.
- Pointer types are supported (framework will handle deref for most positions).

#### Model binding (path-only)

Used to bind a model instance from a path value:

- `model(id)` (recommended)
- `model(id:int)` / `model(code:string)`
- `model(pkg.Type:field)` or `model(pkg.Type)` (default field is `id`)

Behavior:

- Generated binder queries by field and returns first row as the parameter value.
- Auto-imports field helper for query building.

### 1.5 Generate routes + providers + swagger docs

Run from `backend/`:

- Generate routes: `atomctl gen route`
- Generate providers: `atomctl gen provider`
- Generate swagger docs: `atomctl swag init`

### 1.6 Local verify

- Build/run: `make run`
- Use REST client examples: `tests/[module]/[controller].http` (extend it for new endpoints)

### 1.7 Testing

- Prefer existing test style under `backend/tests/e2e`.
- Run: `make test`

### 1.8 Module-level route group (Path + Middlewares)

If you need to define a module HTTP middleware (applies to the module route group):

1) Run `atomctl gen route` first.
2) Edit `backend/app/http/<module>/routes.manual.go`:
- Update `Path()` to return the current module route group prefix (must match the prefix used in `routes.gen.go`, e.g. `/super/v1`, `/t/:tenantCode/v1`).
- Update `Middlewares()` return value: return a list like `[]any{r.middlewares.MiddlewareFunc1, r.middlewares.MiddlewareFunc2, ...}` (no `(...)`), where each item is `r.middlewares.<MiddlewareFunc>` referencing middleware definitions in `backend/app/middlewares`.

---

## 2) Add / update a DB model

Models live in:

- `backend/database/models/*` (generated model code + optional manual extensions)

### 2.1 Migration → model generation workflow

1) Create migration:

- `atomctl migrate create alter_table` or `atomctl migrate create create_table`

2) Edit migration:

- No explicit `BEGIN/COMMIT` needed (framework handles).
- Table name should be plural (e.g. `tenants`).
- MUST: when writing migration content, every field/column MUST include a brief Chinese remark, and also include commented details for that field’s usage scenario and rules/constraints (e.g., valid range/format, default behavior, special cases).

3) Apply migration:

- `atomctl migrate up`

4) Map complex field types (JSON/ARRAY/UUID/…) via transform file:

- `backend/database/.transform.yaml` → `field_type.<table>`

5) Generate models:

- `atomctl gen model`

### 2.2 Enum strategy

- DO NOT use native DB ENUM.
- Define enums in Go under `backend/pkg/consts/<table>.go`, example:

```go
// swagger:enum UserStatus
// ENUM(pending_verify, verified, banned, )
type UserStatus string
```

- For every enum `type` defined under `backend/pkg/consts/`, you MUST also define:
  - `Description() string`: return the Chinese label for the specific enum value (used by API/FE display).
  - `XxxItems() []requests.KV`: return the KV list for FE dropdowns (typically `Key=enum string`, `Value=Description()`). Example: `func TenantStatusItems() []requests.KV` and call it via `consts.TenantStatusItems()`.
  - Prefer `string(t)` as `Key`, and use a stable default label for unknown values (e.g. `未知` / `未知状态`).
  - MUST: `Description()` and `XxxItems()` MUST be placed immediately below the enum `type` definition (same file, directly under `type Xxx string`), to keep the enum self-contained and easy to review.

- Generate enum code: `atomctl gen enum`

### 2.3 Supported field types (`gen/types/`)

`backend/database/.transform.yaml` typically imports `go.ipao.vip/gen` so you can use `types.*` in `field_type`.

Common types:

- JSON: `types.JSON`, `types.JSONMap`, `types.JSONType[T]`, `types.JSONSlice[T]`
- Array: `types.Array[T]`
- UUID: `types.UUID`, `types.BinUUID`
- Date/Time: `types.Date`, `types.Time`
- Money/XML/URL/Binary: `types.Money`, `types.XML`, `types.URL`, `types.HexBytes`
- Bit string: `types.BitString`
- Network: `types.Inet`, `types.CIDR`, `types.MACAddr`
- Ranges: `types.Int4Range`, `types.Int8Range`, `types.NumRange`, `types.TsRange`, `types.TstzRange`, `types.DateRange`
- Geometry: `types.Point`, `types.Polygon`, `types.Box`, `types.Circle`, `types.Path`
- Fulltext: `types.TSQuery`, `types.TSVector`
- Nullable: `types.Null[T]` and aliases (requires DB NULL)

Reference:

- Detailed examples: `gen/types/README.md`

### 2.4 Relationships (GORM-aligned) via `.transform.yaml`

Define in `field_relate.<table>.<FieldName>`:

- `relation`: `belongs_to` | `has_one` | `has_many` | `many_to_many`
- `table`: target table
- `pivot`: join table (many_to_many only)
- `foreign_key`, `references`
- `join_foreign_key`, `join_references` (many_to_many only)
- `json`: JSON field name in API outputs

Generator will convert snake_case columns to Go struct field names (e.g. `class_id` → `ClassID`).

### 2.5 Extending generated models

- Add manual methods/hooks by creating `backend/database/models/<table>.go`.
- Keep generated files untouched                                             ; put custom logic only in your own file(s).

---

## 3) Service layer injection (when adding services)

- Services are in `backend/app/services`.
- Data access boundary:
  - MUST: only the `services` layer may query the database via `models.*Query`, `models.Q.*`, `gorm.DB`, or raw SQL.
  - DO NOT: perform any direct database query from HTTP modules (`backend/app/http/**`) including controllers, DTO binders, or middlewares.
  - HTTP modules must call `services.*` for all read/write operations.
- After creating/updating a service provider, regenerate wiring:
- `atomctl gen service`
- `atomctl gen provider`
- Injection rule: provider injected dependencies MUST be `success`. do not add business-level fallbacks for injection objects nil check.
- Service call conventions:
- **Service-to-service (inside `services` package)**: call directly as `CamelCaseServiceStructName.Method()` (no `services.` prefix).
- **From outside (controllers/handlers/etc.)**: call via the package entrypoint `services.CamelCaseServiceStructName.Method()`.

---

## 4) Quick command summary (run in `backend/`)

- `make run` / `make build` / `make test`
- `atomctl gen route` / `atomctl gen provider` / `atomctl swag init`
- `atomctl migrate create ...` / `atomctl migrate up`
- `atomctl gen model` / `atomctl gen enum` / `atomctl gen service`
- `make init` (full refresh)

---

## 5) Service Layer Unit Testing Guidelines (Generic)

This section is framework-agnostic and applies to any Go service layer (regardless of DI container, ORM, or web framework).

### 5.1 Decide what you are testing

- **Pure unit tests**: no DB/network/filesystem; dependencies are mocked/faked; tests are fast and deterministic.
- **DB-backed tests (recommended whenever the feature touches the database)**: exercise a real database to validate SQL, constraints, transactions, and ORM behavior.
- Always state which tier the test belongs to and keep the scope consistent.

### 5.2 Design the service for testability

- Inject dependencies via constructor or fields; depend on **interfaces**, not concrete DB clients.
- Keep domain logic **pure** where possible: parse/validate/compute should be testable without IO.
- Make time/UUID/randomness deterministic by injecting `Clock`/`IDGenerator` when needed.
- If the feature requires database access, **do not mock the database**; test with an **actual database** (ideally same engine/version as production) to ensure data accuracy. Use mocks/fakes only for non-DB external dependencies when appropriate (e.g., HTTP, SMS, third-party APIs).

### 5.3 Test structure and conventions

- Prefer `*_test.go` with table-driven tests and subtests: `t.Run("case", func(t *testing.T) { ... })`.
- Prefer testing the public API from an external package (`package xxx_test`) unless you must access unexported helpers.
- Avoid “focused” tests in committed code (e.g. `FocusConvey`, `FIt`, `fit`, `it.only`, or equivalent), because they silently skip other tests.
- MUST: in service layer tests, **one test method should focus on one service method** only (e.g. `Test_Freeze` covers `Ledger.Freeze`, `Test_Unfreeze` covers `Ledger.Unfreeze`); do not bundle multiple service methods into a single `Test_*` method.
- MUST: within that single `Test_<Method>` function, cover the method’s key behavior contracts and boundary conditions via subcases (`Convey` blocks or `t.Run`) so the method’s behavior can be reviewed in one place (do NOT claim to cover “all edge cases”, but cover the important ones).
- MUST (minimum set): for each service method test, cover at least: happy path; invalid params / precondition failures; insufficient resources / permission denied (if applicable); idempotency/duplicate call behavior (if applicable); and at least one typical persistence/transaction failure branch (if it is hard to simulate reliably, move that branch coverage to a DB-backed integration/e2e test).

### 5.4 Isolation rules

- Each test must be independent and order-agnostic.
- For integration tests:
  - Use transaction rollback per test when possible; otherwise use truncate + deterministic fixtures.
  - Never depend on developer-local state; prefer ephemeral DB (container) or a dedicated test database/schema.

### 5.5 Assertions and error checks

- Always assert both **result** and **error** (and error types via `errors.Is` / `errors.As` when wrapping is used).
- Keep assertions minimal but complete: verify behavior, not implementation details.
- Use the standard library (`testing`) or a single assertion library consistently across the repo.

### 5.6 Minimal test file template (DI-bootstrapped, DB-backed)

This template matches a common pattern where tests boot a DI container and run against a real database. Replace the bootstrap (`testx.Default/Serve`, `Provide`) and cleanup (`database.Truncate`) with your project's equivalents.

```go
package services

import (
	"database/sql"
	"testing"

	"quyun/v2/app/commands/testx"
	"quyun/v2/database"
	"quyun/v2/database/models"

	. "github.com/smartystreets/goconvey/convey"
	"github.com/stretchr/testify/suite"

	"go.ipao.vip/atom/contracts"
	"go.uber.org/dig"
)

type XxxTestSuiteInjectParams struct {
	dig.In

	DB       *sql.DB
	Initials []contracts.Initial `group:"initials"`
}

type XxxTestSuite struct {
	suite.Suite
	XxxTestSuiteInjectParams
}

func Test_Xxx(t *testing.T) {
	providers := testx.Default().With(Provide)

	testx.Serve(providers, t, func(p XxxTestSuiteInjectParams) {
		suite.Run(t, &XxxTestSuite{XxxTestSuiteInjectParams: p})
	})
}

func (s *XxxTestSuite) Test_Method() {
	Convey("describe behavior here", s.T(), func() {
		ctx := s.T().Context()

		database.Truncate(ctx, s.DB, models.TableNameUser)

		got, err := User.FindByUsername(ctx, "alice")
		So(err, ShouldNotBeNil)
		So(got, ShouldBeNil)
	})
}
```
