扩展Mongoose查询缓存功能：JS转TS遇类型错误求助

错误1：All declarations of 'Query' must have identical type parameters. #

Mongoose原生Query接口包含多个泛型参数，自定义扩展时必须与原接口的泛型签名完全匹配，不能仅声明单个泛型参数。

修复方式：扩展Query接口时使用完整的泛型参数列表，返回类型用this保持链式调用的泛型一致性：

declare module 'mongoose' {
  interface Query<ResultType, DocType, THelpers = {}, RawDocType = DocType, QueryOp = "find", DocTypeFields = Required<DocType>> {
    useCache?: boolean;
    hashKey?: string;
    cache(options?: { key?: unknown }): this;
  }
}

错误2：Argument of type 'IArguments' is not assignable to parameter of type '[]' #

TypeScript对arguments对象的类型检查严格，直接传递会触发类型不匹配报错。可以改用剩余参数接收exec的入参，替代arguments。

修复方式：在exec方法定义中使用剩余参数，调用原生exec时直接传递该参数数组：

Query.prototype.exec = async function (...args: Parameters<typeof exec>): Promise<any> {
  if (!this.useCache) {
    return exec.apply(this, args);
  }
  // 后续代码中统一用args代替arguments
}

错误3：Property 'mongooseCollection' does not exist on type 'Query<...>' #

mongooseCollection是Mongoose内部未对外暴露的属性，TypeScript类型定义中未包含该字段。可以通过公开的this.model.collection.name获取集合名称。

修复方式：替换原集合名称获取代码：

const key = JSON.stringify(Object.assign({}, this.getFilter(), {
  collection: this.model.collection.name,
}));

完整修复后的TypeScript代码 #

import mongoose, { Query } from 'mongoose';
import RedisClient from './redisClient';

// 扩展Mongoose Query接口，匹配完整泛型参数
declare module 'mongoose' {
  interface Query<ResultType, DocType, THelpers = {}, RawDocType = DocType, QueryOp = "find", DocTypeFields = Required<DocType>> {
    useCache?: boolean;
    hashKey?: string;
    cache(options?: { key?: unknown }): this;
  }
}

const exec = Query.prototype.exec;

// 实现cache方法，返回this保持链式调用
Query.prototype.cache = function (options = {}): this {
  this.useCache = true;
  this.hashKey = JSON.stringify(options.key || '');
  return this;
};

// 重写exec方法，使用剩余参数避免arguments类型问题
Query.prototype.exec = async function (...args: Parameters<typeof exec>): Promise<any> {
  if (!this.useCache) {
    return exec.apply(this, args);
  }

  const key = JSON.stringify(Object.assign({}, this.getFilter(), {
    collection: this.model.collection.name,
  }));

  const cachedValue = await RedisClient.getHCache(this.hashKey, key);

  if (cachedValue) {
    const doc = JSON.parse(cachedValue);
    return Array.isArray(doc)
      ? doc.map((d: any) => new this.model(d))
      : new this.model(doc);
  }

  const result = await exec.apply(this, args);
  await RedisClient.setHCache(this.hashKey, key, JSON.stringify(result));

  return result;
};

内容的提问来源于stack exchange，提问作者dayo