mergeByKey
KIT · function · 运行时值
Merge duplicates without moving their first position; selection policy remains host-owned.
The first occurrence of a key fixes the output position; select decides which item that position finally holds, so callers can prefer the newest or the most complete duplicate.
导入
ts
import { mergeByKey } from '@jangts/agent-core/kits/aggregation';js
import { mergeByKey } from '@jangts/agent-core/kits/aggregation';其他公开入口：@jangts/agent-core/types、@jangts/agent-core/kits/aggregation、@jangts/agent-core/kits。
定义
泛型参数
| 类型参数 | 约束 | 默认类型 |
|---|---|---|
Item | — | — |
Key | — | — |
调用
ts
mergeByKey<Item, Key>(items: Iterable<Item>, key: (item: Item) => Key, select: (item: Item, previous: Item | undefined) => Item): Item[]Merge duplicates without moving their first position; selection policy remains host-owned.
The first occurrence of a key fixes the output position; select decides which item that position finally holds, so callers can prefer the newest or the most complete duplicate.
| 类型参数 | 约束 | 默认类型 |
|---|---|---|
Item | — | — |
Key | — | — |
| 参数 | 类型 | 传递 | 说明 |
|---|---|---|---|
items | Iterable<Item> | 必需 | — |
key | (item: Item) => Key | 必需 | — |
select | (item: Item, previous: Item | undefined) => Item | 必需 | — |
返回： Item[]。
使用示例
- Aggregation：查询汇总与稳定合并：顺序读取 App 数据，将重复项如何合并留在同一份配置中。
顺序汇总两次读取
入门 · Node.js
ts
import { Aggregation } from '@jangts/agent-core/kits/aggregation';
const pages = new Map([[1, [{ id: 'a', title: '第一页' }]], [2, [{ id: 'a', title: '重复项' }, { id: 'b', title: '第二页' }]]]);
const query = Aggregation.defineQueryAggregation({ execute: (page: number) => pages.get(page) ?? [] });
console.log(query.collect([1, 2], undefined));js
import { Aggregation } from '@jangts/agent-core/kits/aggregation';
const pages = new Map([[1, [{ id: 'a', title: '第一页' }]], [2, [{ id: 'a', title: '重复项' }, { id: 'b', title: '第二页' }]]]);
const query = Aggregation.defineQueryAggregation({ execute: (page) => pages.get(page) ?? [] });
console.log(query.collect([1, 2], undefined));同一 collect 增加主键与保留策略
配置 · Node.js
ts
import { Aggregation } from '@jangts/agent-core/kits/aggregation';
type Row = { id: string; title: string };
const pages = new Map<number, Row[]>([[1, [{ id: 'a', title: '第一页' }]], [2, [{ id: 'a', title: '重复项' }, { id: 'b', title: '第二页' }]]]);
const query = Aggregation.defineQueryAggregation({
execute: (page: number) => pages.get(page) ?? [],
key: (row: Row) => row.id,
merge: (row: Row, previous: Row | undefined) => previous ?? row,
});
console.log(query.collect([1, 2], undefined));
console.log(Aggregation.mergeByKey([...pages.values()].flat(), row => row.id, (row, previous) => previous ?? row));js
import { Aggregation } from '@jangts/agent-core/kits/aggregation';
const pages = new Map([[1, [{ id: 'a', title: '第一页' }]], [2, [{ id: 'a', title: '重复项' }, { id: 'b', title: '第二页' }]]]);
const query = Aggregation.defineQueryAggregation({
execute: (page) => pages.get(page) ?? [],
key: (row) => row.id,
merge: (row, previous) => previous ?? row,
});
console.log(query.collect([1, 2], undefined));
console.log(Aggregation.mergeByKey([...pages.values()].flat(), row => row.id, (row, previous) => previous ?? row));