Crate entity_derive

Expand description

entity-derive

One macro to rule them all

Generate DTOs, repositories, mappers, and SQL from a single entity definition

§The Problem

Building a typical CRUD application requires writing the same boilerplate over and over: entity struct, create DTO, update DTO, response DTO, row struct, repository trait, SQL implementation, and 6+ From implementations.

That’s 200+ lines of boilerplate for a single entity.

§The Solution

#[derive(Entity)]
#[entity(table = "users")]
pub struct User {
    #[id]
    pub id: Uuid,

    #[field(create, update, response)]
    pub name: String,

    #[field(create, update, response)]
    pub email: String,

    #[field(skip)]
    pub password_hash: String,

    #[field(response)]
    #[auto]
    pub created_at: DateTime<Utc>,
}

Done. The macro generates everything else.

§Installation

[dependencies]
entity-derive = { version = "0.13", features = ["postgres", "api"] }

§Feature flags

Feature	Default	What it does
`postgres`	✓	Generate `sqlx::PgPool`-backed repository implementations
`events`	✓	Generate `{Entity}Event` enum (`Created` / `Updated` / `Deleted` variants)
`commands`	✓	CQRS command pattern: command structs + dispatcher (`#[entity(commands)]`, `#[command(...)]`)
`hooks`	✓	`{Entity}Hooks` trait with before/after lifecycle methods
`transactions`	✓	`{Entity}TransactionRepo` adapter + transaction builder helpers (`#[entity(transactions)]`)
`aggregate_root`	✓	`New{Entity}` constructor type and transactional `save()` (`#[entity(aggregate_root)]`)
`migrations`	✓	Compile-time `MIGRATION_UP` / `MIGRATION_DOWN` SQL constants (`#[entity(migrations)]`)
`projections`	✓	Projection structs and `find_by_id_<projection>` lookups (`#[projection(...)]`)
`clickhouse`		Generate ClickHouse-backed repositories (planned)
`mongodb`		Generate MongoDB-backed repositories (planned)
`streams`		`{Entity}Subscriber` using Postgres `LISTEN`/`NOTIFY` (pulls in `events`)
`outbox`		Transactional-outbox enqueue in generated writes + `OutboxDrainer` runtime (pulls in `events`)
`api`		Generate HTTP handlers (`axum`) and `utoipa` OpenAPI schemas
`validate`		Wire up `validator::Validate` on generated DTOs
`tracing`		Wrap every generated async method in `#[tracing::instrument]` carrying `entity` + `op` span fields

Default features cover the full entity-attribute surface so existing projects work without changes. For lean builds, opt out of what you don’t need:

[dependencies]
# Just repositories — no events, hooks, commands, etc.
entity-derive = { version = "0.13", default-features = false, features = ["postgres"] }

If you use an entity attribute whose feature is disabled (e.g. #[entity(commands)] without features = ["commands"]), the macro emits a compile_error! at the attribute pointing to the missing feature.

Enable extras alongside the defaults:

[dependencies]
entity-derive = { version = "0.13", features = ["postgres", "api", "tracing", "streams"] }
tracing = "0.1"
tracing-subscriber = "0.3"

§Features

Feature	Description
Zero Runtime Cost	All code generation at compile time
Type Safe	Change a field once, everything updates
Auto HTTP Handlers	`api(handlers)` generates CRUD endpoints + router
`OpenAPI` Docs	Auto-generated Swagger/OpenAPI documentation
Query Filtering	Type-safe `#[filter]`, `#[filter(like)]`, `#[filter(range)]`
Relations	`#[belongs_to]` and `#[has_many]`
Ownership Scoping	`#[owner]` generates `find_by_id_scoped` / `list_by_owner` / `update_scoped` / `delete_scoped`
Upsert	`upsert(conflict = "…")` generates `INSERT ... ON CONFLICT DO UPDATE / DO NOTHING`
Aggregate Roots	`#[entity(aggregate_root)]` with `New{T}` DTOs and transactional `save`
Transactions	Multi-entity atomic operations
Lifecycle Events	`Created`, `Updated`, `Deleted` events
Real-Time Streams	Postgres LISTEN/NOTIFY integration
Transactional Outbox	`events(outbox)` — durable at-least-once event delivery with retry/backoff
Lifecycle Hook Traits	`{Entity}Hooks` trait emitted with `before_create` / `after_update` / etc.; invocation is currently manual at your service layer (tracking auto-invocation: #127)
CQRS Commands	Business-oriented command pattern
Soft Delete	`deleted_at` timestamp support
Structured Logging	Opt-in `tracing` feature wraps every generated async method in `#[tracing::instrument]` with `entity` + `op` fields

§Documentation

Topic	Languages
Getting Started
Attributes	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Examples	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Features
Filtering	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Relations	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Events	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Streams	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Hooks	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Commands	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Advanced
Custom SQL	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Web Frameworks	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳
Best Practices	🇬🇧 🇷🇺 🇰🇷 🇪🇸 🇨🇳

§Quick Reference

§Entity Attributes

#[entity(
    table = "users",           // Required: table name
    schema = "public",         // Optional: schema (default: omitted)
    dialect = "postgres",      // Optional: database dialect
    aggregate_root,            // Optional: New{T} DTOs + transactional save
    soft_delete,               // Optional: use deleted_at instead of DELETE
    upsert(                    // Optional: INSERT ... ON CONFLICT method
        conflict = "email",    // #[column(unique)] field(s) or unique_index columns
        action = "update",     // "update" (default) or "nothing"
    ),
    events,                    // Optional: generate lifecycle events
    events(outbox),            // Optional: + durable transactional outbox
    streams,                   // Optional: real-time Postgres NOTIFY
    hooks,                     // Optional: before/after lifecycle hooks
    commands,                  // Optional: CQRS command pattern
    transactions,              // Optional: multi-entity transaction support
    api(                       // Optional: generate HTTP handlers + OpenAPI
        tag = "Users",
        handlers,              // All CRUD, or handlers(get, list, create)
        security = "bearer",   // cookie, bearer, api_key, or none
        guard = "RequireAuth", // FromRequestParts extractor enforced in handlers
        guard(list = "none"),  // per-op override: create/get/update/delete/list/commands
        title = "My API",
        api_version = "1.0.0",
    ),
)]

§Field Attributes

#[id]                          // Primary key (auto-generated UUID)
#[auto]                        // Auto-generated (timestamps)
#[owner]                       // Ownership column: adds *_scoped methods
#[field(create)]               // Include in CreateRequest
#[field(update)]               // Include in UpdateRequest
#[field(response)]             // Include in Response
#[field(skip)]                 // Exclude from all DTOs
#[filter]                      // Exact match filter
#[filter(like)]                // ILIKE pattern filter
#[filter(range)]               // Range filter (from/to)
#[belongs_to(Entity)]          // Foreign key relation
#[has_many(Entity)]            // One-to-many relation
#[projection(Name: fields)]    // Partial view

§Transactional Outbox

LISTEN/NOTIFY (streams) is fire-and-forget: events are lost if no subscriber is listening. events(outbox) makes delivery durable — every generated write inserts the serialized event into the entity_outbox table in the same transaction as the DML, and a drainer delivers rows with retry and exponential backoff:

#[derive(Entity, Serialize, Deserialize)]
#[entity(table = "orders", events(outbox), migrations)]
pub struct Order { /* ... */ }

sqlx::query(Order::MIGRATION_OUTBOX).execute(&pool).await?;

struct Notifier;

#[async_trait::async_trait]
impl entity_core::outbox::OutboxHandler for Notifier {
    type Error = anyhow::Error;
    async fn handle(&self, row: &OutboxRow) -> Result<(), Self::Error> {
        deliver(&row.entity, &row.payload).await
    }
}

entity_core::outbox::OutboxDrainer::new(pool, Notifier).run().await;

Rows are claimed with FOR UPDATE SKIP LOCKED (multiple drainers cooperate), retried with exponential backoff and parked after max_attempts for manual inspection. Delivery is at-least-once — handlers must be idempotent. Composes with streams: NOTIFY wakes subscribers instantly, the outbox guarantees nothing is lost. Requires the outbox feature and serde_json in your crate.

§Ownership Scoping

Mark the column carrying the owning principal’s id with #[owner] and the repository gains row-level scoped methods — “only this user’s rows” without hand-written predicates:

#[derive(Entity)]
#[entity(table = "orders")]
pub struct Order {
    #[id]
    pub id: Uuid,
    #[owner]
    pub user_id: Uuid,
    #[field(create, update, response)]
    pub note: String,
}

let mine: Vec<Order> = pool.list_by_owner(user_id, 20, 0).await?;
let order = pool.find_by_id_scoped(id, user_id).await?;          // None if not theirs
let updated = pool.update_scoped(id, user_id, patch).await?;     // None if not theirs
let removed = pool.delete_scoped(id, user_id).await?;            // false if not theirs

Scoped reads and writes never reveal whether a row exists for another owner, and all of them respect soft_delete.

§Handler Guards

security = "..." only documents authentication in the OpenAPI spec. To actually enforce it, pass a guard — any type implementing axum’s FromRequestParts. It is injected as a leading argument of every generated handler, so a failed extraction rejects the request before the handler body runs:

pub struct RequireAuth;

impl<S: Send + Sync> FromRequestParts<S> for RequireAuth {
    type Rejection = StatusCode;
    async fn from_request_parts(parts: &mut Parts, _: &S) -> Result<Self, Self::Rejection> {
        parts.headers.contains_key("authorization")
            .then_some(Self)
            .ok_or(StatusCode::UNAUTHORIZED)
    }
}

#[derive(Entity)]
#[entity(table = "users", api(tag = "Users", handlers, guard = "RequireAuth", guard(list = "none")))]
pub struct User { /* ... */ }

Per-operation overrides accept create, get, update, delete, list and commands; the literal "none" disables the guard for that operation. Commands listed in public = [...] never receive a guard.

§Postgres Enums

Derive ValueObject on a status-style enum and reference it from entities with #[column(pg_enum = "...")]:

#[derive(ValueObject, Debug, Clone, Serialize, Deserialize)]
#[value_object(pg_type = "order_status", sqlx)]
pub enum OrderStatus { Pending, Shipped, Delivered }

#[derive(Entity)]
#[entity(table = "orders", migrations)]
pub struct Order {
    #[id]
    pub id: Uuid,
    #[field(create, update, response)]
    #[column(pg_enum = "order_status")]
    pub status: OrderStatus,
}

for ddl in Order::MIGRATION_TYPES {
    sqlx::query(ddl).execute(&pool).await?;
}
sqlx::query(Order::MIGRATION_UP).execute(&pool).await?;

ValueObject generates PG_TYPE and idempotent PG_CREATE_TYPE constants; the opt-in sqlx flag additionally emits sqlx::Type / Encode / Decode impls so the enum binds and decodes without hand-written glue (omit it if you already derive sqlx::Type yourself).
#[column(pg_enum = "...")] sets the DDL column type and registers the enum’s DDL in {Entity}::MIGRATION_TYPES — run those before MIGRATION_UP.
The declared name is checked against the enum’s pg_type at compile time; a typo fails the build.

§Upsert

Declare a conflict target with a uniqueness guarantee (#[id], #[column(unique)] or unique_index(...)) and the repository gains an upsert method backed by INSERT ... ON CONFLICT:

#[derive(Entity)]
#[entity(table = "users", upsert(conflict = "email"))]
pub struct User {
    #[id]
    pub id: Uuid,
    #[field(create, response)]
    #[column(unique)]
    pub email: String,
    #[field(create, update, response)]
    pub name: String,
}

let user = pool.upsert(CreateUserRequest { email, name }).await?;

action = "update" (default) overwrites all non-conflict columns with the incoming values (DO UPDATE SET col = EXCLUDED.col) and returns the persisted row. action = "nothing" keeps the existing row (DO NOTHING) and returns Option<Entity> — None when a conflicting row already existed. Requires returning = "full" (the default). With streams enabled, upsert publishes a Created notification for every row it returns.

§Transactions

Mark each participating entity with #[entity(table = "…", transactions)] and drive a multi-entity transaction through Transaction::run. The closure receives &mut TransactionContext; run commits on Ok and rolls back on Err (or any panic) automatically:

use entity_core::transaction::Transaction;

Transaction::new(&pool)
    .run(async |ctx| {
        let user = ctx.users().create(create_user).await?;
        ctx.orders().create(order_for(user.id)).await?;
        Ok::<_, sqlx::Error>(user)
    })
    .await?;

Need conditional commit/rollback inside the closure? Use run_with_commit — it takes TransactionContext by value so the closure can call ctx.commit().await (or ctx.rollback().await) itself.

§Tracing

Opt-in with the tracing feature. Every generated async method (create, find_by_id, update, delete, list, find_by_<field>, projections, transaction adapters, stream subscribers) is wrapped in #[tracing::instrument(skip_all, fields(entity, op), err(Debug))].

entity-derive = { version = "0.13", features = ["postgres", "tracing"] }
tracing = "0.1"
tracing-subscriber = { version = "0.3", features = ["env-filter"] }

With a subscriber initialized, a failed User::create surfaces as:

ERROR entity.User.create: error=database error: duplicate key value violates unique constraint
  in entity.User.create with entity="User" op="create"

When the feature is off, generated code is byte-for-byte identical to a build without the attribute — zero runtime cost.

§Code Coverage

§entity-derive

One crate, all features. Re-exports:

Entity derive macro from entity-derive-impl
All types from entity-core (Pagination, SortDirection, Repository)

§Quick Start

use entity_derive::{Entity, Pagination};

#[derive(Entity)]
#[entity(table = "users")]
pub struct User {
    #[id]
    pub id: Uuid,
    #[field(create, update, response)]
    pub name: String,
}

// Use pagination
let page = Pagination::page(0, 25);

Modules§

outboxoutbox: Transactional-outbox drainer runtime.
policy: Policy/authorization types for entity-derive.
prelude: Convenient re-exports for common usage.
streamstreams: Streaming types for real-time entity updates.
transaction: Transaction support for entity-derive.

Structs§

Pagination: Pagination parameters for list operations.

Enums§

CommandKind: Kind of business command.
EventKind: Kind of lifecycle event.
SortDirection: Sort direction for ordered queries.

Traits§

EntityCommand: Base trait for entity commands.
EntityEvent: Base trait for entity lifecycle events.
Repository: Base repository trait.

Functions§

const_str_eq: Compare two strings in const context.

Attribute Macros§

async_trait

Derive Macros§

Entity: Derive macro for generating complete domain boilerplate from a single entity definition.
ValueObject: Derive macro for generating PostgreSQL enum boilerplate.