Angular2 - 多个依赖的顺序http api调用

不确定我是否完全理解你的问题，但这就是我所做的：

Not sure if I totally understand your question, but here is what I do:

我进行第一次http调用，然后当订阅fires，它调用completeLogin。然后我可以使用自己的完整函数触发另一个http调用并重复链接。

I make the first http call, then when the subscribe fires, it calls completeLogin. I could then fire another http call with its own complete function and repeat the chain.

这是组件代码。用户已填写登录信息并按下登录信息：

Here is the component code. The user has filled in the login information and pressed login:

onSubmit() {
   console.log(' in on submit');
   this.localUser.email = this.loginForm.controls["email"].value;
   this.localUser.password = this.loginForm.controls["password"].value;
   this.loginMessage = "";
   this.checkUserValidation();
}

checkUserValidation() { 
   this.loginService.getLoggedIn()
      .subscribe(loggedIn => {
         console.log("in logged in user validation")
         if(loggedIn.error != null || loggedIn.error != undefined || loggedIn.error != "") {
            this.loginMessage = loggedIn.error;
         }
      });

      this.loginService.validateUser(this.localUser);
}

这会调用loginservice ValidateUser方法

This calls the loginservice ValidateUser method

validateUser(localUser: LocalUser) {
   this.errorMessage = "";
   this.email.email = localUser.email;
   var parm = "validate~~~" + localUser.email + "/"
   var creds = JSON.stringify(this.email);
   var headers = new Headers();
   headers.append("content-type", this.constants.jsonContentType);

   console.log("making call to validate");
   this.http.post(this.constants.taskLocalUrl + parm, { headers: headers })
      .map((response: Response) => {
         console.log("json = " + response.json());
         var res = response.json();
         var result = <AdminResponseObject>response.json();
         console.log(" result: " + result);
         return result;
      })
      .subscribe(
         aro => {
            this.aro = aro
         },
         error => {
            console.log("in error");
            var errorObject = JSON.parse(error._body);
            this.errorMessage = errorObject.error_description;
            console.log(this.errorMessage);
         },
         () => this.completeValidateUser(localUser));
            console.log("done with post");
     }

completeValidateUser(localUser: LocalUser) {
   if (this.aro != undefined) {
      if (this.aro.errorMessage != null && this.aro.errorMessage != "") {
         console.log("aro err " + this.aro.errorMessage);
         this.setLoggedIn({ email: localUser.email, password: localUser.password, error: this.aro.errorMessage });
      } else {
         console.log("log in user");
         this.loginUser(localUser);
      }
   } else {
      this.router.navigate(['/verify']);
   }

}

在我的登录服务中，我调用授权服务，该服务返回一个可观察的令牌。

In my login service I make a call to the authorization service which returns an observable of token.

loginUser(localUser: LocalUser) {
   this.auth.loginUser(localUser)
   .subscribe(
      token => {
         console.log('token = ' + token)
         this.token = token
      },
      error => {
         var errorObject = JSON.parse(error._body);
         this.errorMessage = errorObject.error_description;
         console.log(this.errorMessage);
         this.setLoggedIn({ email: "", password: "", error: this.errorMessage });
      },
      () => this.completeLogin(localUser));
}

在授权服务中：

loginUser(localUser: LocalUser): Observable<Token> {
   var email = localUser.email;
   var password = localUser.password;

    var headers = new Headers();
    headers.append("content-type", this.constants.formEncodedContentType);

    var creds:string = this.constants.grantString + email + this.constants.passwordString + password;
    return this.http.post(this.constants.tokenLocalUrl, creds, { headers: headers })
         .map(res => res.json())
}

此代码中的重点是，在响应时，首先调用登录服务的validateUser方法，基于返回信息，如果有效，我在登录服务上调用loginUser方法。只要你需要，这条链就可以继续。您可以设置类级变量来保存链中每个方法所需的信息，以便决定下一步该做什么。

The point here in this code, is to first call the validateUser method of the login service, upon response, based on the return information, if its valid, I call the loginUser method on the login service. This chain could continue as long as you need it to. You can set class level variables to hold the information that you need in each method of the chain to make decisions on what to do next.

另请注意，您可以订阅在服务中返回并在那里处理它，它不必返回组件。

Notice also that you can subscribe to the return in the service and process it there, it doesn't have to return to the component.

好的，接下来：

public getShows():any {
   this._ShowsHttpService
      .getShows()
      .subscribe(
         w => this.shows = w,
         error => this.errorMessage = error,
         () => this.completeGetShows());
}

completeGetShow() {

   //any logic here to deal with previous get;

   this.http.get#2()
      .subscribe(
         w => this.??? = w),
         error => this.error = error,
         () => this.completeGet#2);
}

completeGet#2() {

   //any logic here to deal with previous get;

   this.http.get#3()
      .subscribe(
         w => this.??? = w),
         error => this.error = error,
         () => this.completeGet#3);
}

completeGet#3() {

   //any logic here to deal with previous get;

   //another http: call like above to infinity....
}