Trait Observer 

pub trait Observer: Send + Sync {
    // Provided methods
    fn name(&self) -> &str { ... }
    fn before_insert(
        &self,
        _ctx: &HookContext,
        _attrs: &mut HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
    fn after_insert(
        &self,
        _ctx: &HookContext,
        _attrs: &HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
    fn before_update(
        &self,
        _ctx: &HookContext,
        _attrs: &mut HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
    fn after_update(
        &self,
        _ctx: &HookContext,
        _attrs: &HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
    fn before_delete(
        &self,
        _ctx: &HookContext,
        _attrs: &HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
    fn after_delete(
        &self,
        _ctx: &HookContext,
        _attrs: &HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
    fn after_find(
        &self,
        _ctx: &HookContext,
        _attrs: &mut HashMap<String, Value>,
    ) -> SubscriberResult<()> { ... }
}

模型观察者 trait

与 EventSubscriber 不同，Observer 默认订阅所有事件。 适合需要监控所有生命周期事件的场景（如审计日志）。

实现要点

• 所有方法默认实现为 no-op，按需 override
• 任何方法返回 Err(SubscriberError::Vetoed) 会中止 before 事件的后续执行

Provided Methods

fn name(&self) -> &str

观察者名称（用于日志与错误信息）

fn before_insert( &self, _ctx: &HookContext, _attrs: &mut HashMap<String, Value>, ) -> SubscriberResult<()>

插入前

fn after_insert( &self, _ctx: &HookContext, _attrs: &HashMap<String, Value>, ) -> SubscriberResult<()>

插入后

fn before_update( &self, _ctx: &HookContext, _attrs: &mut HashMap<String, Value>, ) -> SubscriberResult<()>

更新前

fn after_update( &self, _ctx: &HookContext, _attrs: &HashMap<String, Value>, ) -> SubscriberResult<()>

更新后

fn before_delete( &self, _ctx: &HookContext, _attrs: &HashMap<String, Value>, ) -> SubscriberResult<()>

删除前

fn after_delete( &self, _ctx: &HookContext, _attrs: &HashMap<String, Value>, ) -> SubscriberResult<()>

删除后

fn after_find( &self, _ctx: &HookContext, _attrs: &mut HashMap<String, Value>, ) -> SubscriberResult<()>

单行查询后

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors