Struct CompositeKeyExtractor 

pub struct CompositeKeyExtractor { /* private fields */ }

复合键提取器：组合多个 extractor，结果以 : 拼接

示例

use sz_orm_sharding::routing::{CompositeKeyExtractor, FieldExtractor};

let ext = CompositeKeyExtractor::new()
    .with(FieldExtractor::new(|| "cn".to_string()))
    .with(FieldExtractor::new(|| "user:123".to_string()));
// extract 后得到 "cn:user:123"

Implementations

impl CompositeKeyExtractor

pub fn new() -> Self

创建空的复合提取器

pub fn with<E>(self, extractor: E) -> Self

where E: ShardKeyExtractor + 'static,

添加一个子提取器（链式 API）

命名为 with 而非 add，避免与 std::ops::Add::add trait 方法混淆。

pub fn len(&self) -> usize

返回子提取器数量

pub fn is_empty(&self) -> bool

是否为空

Trait Implementations

impl Debug for CompositeKeyExtractor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CompositeKeyExtractor

fn default() -> Self

Returns the “default value” for a type.

impl ShardKeyExtractor for CompositeKeyExtractor

fn extract(&self, data: &dyn Any) -> Result<String, ShardingError>

从数据中提取分片键