如何等待多個請求

我試圖找出等待多個請求并在完成后做某事的最佳方法是什么，請記住，兩個請求同時請求午餐，他們不應該互相等待。

  // table filling
  public SUB_getActSearch: Subscription;


  // table filling 2
  public SUB_getDeclarationSearch: Subscription;

  public fillTable(): void {
    const searchOBJ = {
      CreateDateFrom: this.currentDate,
      CreateDateTo: this.currentDate,
      ActNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      vinCode: this.vinCode == undefined ? '' : this.vinCode,
      GovNumber: this.GovNumber == undefined ? '' : this.GovNumber,
      IsFromDashboard: true
    };
    const searchOBJ2 = {
      ActNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      vinCode: this.vinCode == undefined ? '' : this.vinCode,
      GovNumber: this.GovNumber == undefined ? '' : this.GovNumber,
    };
    if ((this.ActNumber && this.ActNumber != undefined && this.ActNumber != null) || (this.vinCode && this.vinCode != undefined && this.vinCode != null) || (this.GovNumber && this.GovNumber != undefined && this.GovNumber != null)) {
      this.SUB_getActSearch = this.searchService.getActSearch({ ...searchOBJ2, PageSize: this.pageSize, PageNumber: this.currentPage }).subscribe((res) => {
        this.Act_Data = [];
        let headerPagin = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLength = headerPagin.totalCount;
        this.currentPage = headerPagin.currentPage;
        this.pageSize = headerPagin.pageSize;
        res.body.map((param) => {
          this.Act_Data.push(param);
        });
        this.ActDataSource = new MatTableDataSource<Element>(this.Act_Data);
        // console.log('Your form data : ', this.ActDataSource);
      });
    } else {
      this.SUB_getActSearch = this.searchService.getActSearch({ ...searchOBJ, PageSize: this.pageSize, PageNumber: this.currentPage }).subscribe((res) => {
        this.Act_Data = [];
        let headerPagin = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLength = headerPagin.totalCount;
        this.currentPage = headerPagin.currentPage;
        this.pageSize = headerPagin.pageSize;
        res.body.map((param) => {
          this.Act_Data.push(param);
        });
        this.ActDataSource = new MatTableDataSource<Element>(this.Act_Data);
        // console.log('Your form data : ', this.ActDataSource);
      });
    }
  }


  public fillTable2(): void {
    const searchOBJ = {
      DeclarationCreateDateFrom: this.currentDate.substring(0, 10),
      DeclarationCreateDateTo: this.currentDate,
      DeclarationNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      VinCode: this.vinCode == undefined ? '' : this.vinCode,
      TransitNumber: this.GovNumber == undefined ? '' : this.GovNumber,
    };
    const searchOBJ2 = {
      DeclarationNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      VinCode: this.vinCode == undefined ? '' : this.vinCode,
      TransitNumber: this.GovNumber == undefined ? '' : this.GovNumber,
    };
    if ((this.ActNumber && this.ActNumber != undefined && this.ActNumber != null) || (this.vinCode && this.vinCode != undefined && this.vinCode != null) || (this.GovNumber && this.GovNumber != undefined && this.GovNumber != null)) {
      this.SUB_getDeclarationSearch = this.declarationsService.getDeclarations({ ...searchOBJ, IsFromDashboard: true, PageSize: this.pageSizeDecl, PageNumber: this.currentPageDecl }).subscribe((res) => {
        this.Declaration_Data = [];
        let headerPaginDecl = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLengthDecl = headerPaginDecl.totalCount;
        this.currentPageDecl = headerPaginDecl.currentPage;
        this.pageSizeDecl = headerPaginDecl.pageSize;
        res.body.map((param) => {
          this.Declaration_Data.push(param);
        });
        this.DeclarationDataSource = new MatTableDataSource<Element>(this.Declaration_Data);
        // console.log('Your form data : ', this.DeclarationDataSource);
      });
    } else {
      this.SUB_getDeclarationSearch = this.declarationsService.getDeclarations({ ...searchOBJ, IsFromDashboard: true, PageSize: this.pageSizeDecl, PageNumber: this.currentPageDecl }).subscribe((res) => {
        this.Declaration_Data = [];
        let headerPaginDecl = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLengthDecl = headerPaginDecl.totalCount;
        this.currentPageDecl = headerPaginDecl.currentPage;
        this.pageSizeDecl = headerPaginDecl.pageSize;
        res.body.map((param) => {
          this.Declaration_Data.push(param);
        });
        this.DeclarationDataSource = new MatTableDataSource<Element>(this.Declaration_Data);
        // console.log('Your form data : ', this.DeclarationDataSource);
      });
    }
  }

在ngoninit 中呼叫了兩種方法：fillTable() 和fillTable2()。

我嘗試使用以下方法來收聽訂閱并等待他們

  public testingforkJoin(): void {
    forkJoin([this.SUB_getActSearch, this.SUB_getDeclarationSearch]
    ).subscribe(val => 
console.log("xxxxx", val));
// call some method here as soon as both are done
  }

但事實證明 forkJoin 不能監聽訂閱，有沒有其他類似于 forkjoin 的訂閱方式？

有兩種方法包括 HTTP 請求，我想等待兩個網路請求完成并在完成后立即執行某些操作。

uj5u.com熱心網友回復：

我通常會宣告一些布爾變數來解決此類異步問題。在你的情況下，它看起來像：

isSearch: boolean; isDeclarationSearch: boolean;

然后我將每個變數初始化為 false，在每個變數的末尾我將值更改為 true，然后我創建了當兩個值都為 true 時作業的新函式。

uj5u.com熱心網友回復：

forkJoin 的重點是你會訂閱它，而不是單獨訂閱，它會在訂閱中一次回傳所有結果

let call: [] = [];

call.push(this.declarationsService.getDeclarations1()); call.push(this.declarationsService.getDeclarations2()); call.push(this.declarationsService.getDeclarations3());

forkJoin(call).subscribe((res) => {  }); 

或者

 forkJoin({
 'prop1' :this.declarationsService.getDeclarations1()
 'prop2' : this.declarationsService.getDeclarations2()
}).subscribe((result) => { result.prop1; result.prop2   }); 

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