Angular2/4 http.get嵌套访问“这个”

Question

我有这样的一段代码

let headers = new Headers({ 'Authorization': `${this.user.Token}` }); 
     let options = new RequestOptions({ headers: headers }); 
     this.http.get(environment.apiRoot + 'Customers/Customer/Search/' + term + '/' + value, options) 
      .map((response) => { 
       var Data = response.json().Data; 
       return Data; 
      }).subscribe(Data => { 
       this.data.customer.emailAddress = Data.EmailAddress; 
       this.data.customer.phoneNumber = Data.PhoneNumber; 
       this.data.customer.firstName = Data.FirstName; 
       this.data.customer.lastName = Data.LastName; 
       this.data.customer.streetAddress = Data.StreetAddress; 
       this.data.customer.city = Data.City; 
       this.data.customer.state = Data.State; 
       this.data.customer.zipCode = Data.ZipCode; 
       this.data.customer.idNumber = Data.IDNumber; 
       this.data.customer.ID = Data.ID; 
       this.data.customer.comment = Data.Comment; 

       // //Check if customer has exsiting orders 
       this.http.request(environment.apiRoot + 'Orders/Order/Customer/' + Data.ID, options) 
        .subscribe(odResponse => { 
         var Data = odResponse.json().Data; 
         this.data.orders = Data; 
         this.existingOrders = Data.length > 0; 
        }, error => { 
         this.alertService.error('Encountered an error while trying to get customer order data'); 
        }); 
      }, error => { 
       this.alertService.error('Encountered an error while trying to get customer data'); 
      }); 

我遇到的问题是，当第一个“GET”完成了“this.data.customer “即使在调试器中，”this“显示为订阅而不是我的组件，那么当第二个”GET“执行”this“时，订阅并且说”this.data.order“是未定义的，所以是“this.data”

所以我想问题是我如何得到“this”在我的订阅是组件而不是订阅。

Answer 1

正如哈利所说，最好使用switchMap并在订阅中进行一次订阅呼叫而不是呼叫。在问候的解决方案，试试这个

let headers = new Headers({ 'Authorization': `${this.user.Token}` }); 
let options = new RequestOptions({ headers: headers }); 

this.http.get(environment.apiRoot + 'Customers/Customer/Search/' + term + '/' + value, options) 
     .map((response) => { // This extracts the data you require 
      var Data = response.json().Data; 

      return Data; 
     }).switchMap(Data => { // This returns the result of the second observable in 
      return this.http.request(environment.apiRoot + 'Orders/Order/Customer/' + Data.ID, options) 
          .map(odResponse => { // We have the response. Extract the json, and return an array with the first element as the old data, and the second element as the new data. 
           var _Data = odResponse.json().Data; 
           return [ Data, _Data ]; 
          }); 
     }).subscribe(data => { 
      let firstSet = data[0]; 
      let secondSet = data[1]; 
      // Now do your assignment 
      this.data.customer.emailAddress = firstSet.EmailAddress; 
      this.data.customer.phoneNumber = firstSet.PhoneNumber; 
      ... 
      ... 
     }); 

我用这个方法，因为它似乎你需要第一次调用（标识）返回的数据，以便能够使第二个呼叫。如果不是这样的话，我会建议使用Observable.forkJoin。 This是RxJS V4中forkJoin的文档，但它仍适用于V5。