已解决的承诺 returns 未定义，但它具有价值

Question

我遇到了一个令人沮丧的问题，我找不到它发生的原因

我有一个函数如下：

  public async PageResult(searchRecord:Search,authorization:string,pageNumber:number,databaseName:string){

    some codes .....
    return new Promise((resolve, reject) => {
      this._resultsDatastore.bulkInsert(
        databaseName,
        objects
      ).then(succ => {
        // I can see succ is printed successfully in console
        console.log(succ);
        // when I resolve it here I assume I am returning the result
        resolve(succ)
      }, err => {
        console.log(err);
        reject(err)
      })
    })
  }

所以你可以看到我解决了（成功），这样我就把成功返回给调用者函数

现在我有：

 public async loadResults(
    searchId: string,
    authorization: string
  ) {

   some code....
    const results = udsQuery.pages.map(async (pageNumber: number) => await this.PageResult(searchRecord,authorization,pageNumber,databaseName))


    let all: any=[];
    await Promise.all(results).catch(e => {
      console.log("^^^^^^^^^^^^^^^^^^^^^EEEERRRRRROR^^^^^^^^^^^^^^^^^^^^^^");
    }).then(res=>{
      console.log("suuuuuuuuuuuuuuucesssssssssssssss");
      // issue is here: below prints undefined though succ has value 
      console.log(res);
      all.push(res);
      return res;
    });

  }

所以现在我在地图中调用 PageResult 并使用 promis.all 重新爱它而不是我在 PageResult 中返回的 succ 我得到未定义请参阅上面代码中的这一部分：

  console.log("suuuuuuuuuuuuuuucesssssssssssssss");
  // issue is here: below prints undefined though succ has value 
  console.log(res);

我错过了什么吗？

Answer 1

不知怎么的，我不喜欢你写代码的方式，我试着先修改那个代码。我还看到了另一个错误，你正在执行你的 PageResult() 函数，而不是它应该由 Promise.all 块执行。

我没有测试代码，但它应该是这样的：

 public async PageResult(searchRecord:Search,authorization:string,pageNumber:number,databaseName:string){

        try
        {
            const succ =  await this._resultsDatastore.bulkInsert(
                databaseName,
                objects);
            return succ;
        }
        catch (e)
        {
            throw e;
        }
    }


    public loadResults(searchId: string, authorization: string )
    {   
        const all: any=[];
        const pormises: any=[];
        const results = udsQuery.pages.map((pageNumber: number) =>
            pormises.push(this.PageResult(searchRecord, authorization, pageNumber, databaseName)));

        return new Promise((resolve, reject) =>
        {
            Promise.all(results)
                .then(res=>
                {
                    console.log("suuuuuuuuuuuuuuucesssssssssssssss");
                    // issue is here: below prints undefined though succ has value

                    console.log(res);
                    all.push(res);

                    return resolve(all);
                })
            .catch(e =>
            {
                console.log("^^^^^^^^^^^^^^^^^^^^^EEEERRRRRROR^^^^^^^^^^^^^^^^^^^^^^");
            });
        });

    }

已解决的承诺 returns 未定义，但它具有价值

resolved promise returns undefined though it has value

node.js

promise

es6-promise