我如何在 angular2 中获取字符串 json

Posted 2023-02-22

【中文标题】我如何在 angular2 中获取字符串 json

【英文标题】：how can i get string json in angular2

【发布时间】：2017-09-16 13:19:33

【问题描述】：

在我的 angular2 组件中

keyword_test=;

getData() 
    this.service.getData()
        .subscribe(
            data => 
                this.keyword_test = data
                console.log(data);
                console.log(this.keyword_test);
            );

console.log(data) 和 console.log(this.keyword_test) 像这样打印正确的数据

                
                    "caption": "folder0",
                    "type": "folder",
                    "subnodes": [
                        
                            "caption": "folder1",
                            "type": "folder",
                            "subnodes": [
                                
                                    "caption": "keyword1",
                                    "type": "keyword",
                                    "search_filter_expression": "sfe1"
                                ,
                                
                                    "caption": "keyword2",
                                    "type": "keyword",
                                    "search_filter_expression": "sfe2"
                                
                            ]
                        ,
                        
                            "caption": "folder2",
                            "type": "folder",
                            "subnodes": [
                                
                                    "caption": "keyword3",
                                    "type": "keyword",
                                    "search_filter_expression": "sfe3"

                                ,
                                
                                    "caption": "keyword4",
                                    "type": "keyword",
                                    "search_filter_expression": "sfe4"

                                
                            ]
                        
                    ]
                

但在我的 ngOnInit 中

 ngOnInit() 
    this.getData();
    console.log(this.keyword_test);

尽管 this.getdata(), this.keyword_test print "Object " 我认为没有对象。 是keyword_test 初始化不正确吗？ 当我在 getData 函数中打印 console.log(typeof data) 时，结果是字符串... 服务中确实改成json了，不知道为什么。

++这是我的服务

@Injectable()
export class keywordService 
    private API_URI: string = 'MYAPIURL';

    constructor(private http: Http) 
    

    getData() 
        return this.http.get(this.API_URI, body: "")
            .map(res => res.json();
        );
    

【问题讨论】：

在keyword_test中手动输入会正常工作。

【参考方案1】：

 ngOnInit() 
    this.getData(); // this execute but data arrives with call back
    console.log(this.keyword_test); //this execute before data has arrived and thats why it is not printing the result from success call

正确的方法

this.service.getData()
   .subscribe(
       data => 
          this.keyword_test = data
          console.log(data);
          console.log(this.keyword_test);
);