Angular 2 Observables implementation

Question

我正试图用反应式编程方法来包装我的逻辑。

我有两个依赖数据集可能或可能不在本地存储。不过，我需要先计算一个，然后计算第二个。

因此，像这样：

let storageCategories = this.ls.retrieve('categories'); 
if (storageCategories) { 
    // Found in localStorage 
    this.allCategories = storageCategories; 
} else { 
    // Send an HTTP API request and fetch categories 
    // After request is successful lookup for 'result' in localstorage 
    // If result not in localstorage send an HTTP API request 
} 


// RESULT LOGIC 
let storageResult = this.ls.retrieve('result'); 
if (storageResult) { 
    // Found in localStorage 
    return new BehaviorSubject<any>(this.processResultData(storageResult)); 
} else { 
    // Send an HTTP API request and fetch result 
    // If request is successful save in localstorage and return 
} 

现在的基本问题是我不想写在两个地方的结果逻辑：（1）第一if的else和（2）后的类别if

有没有办法让结果逻辑只在一个地方（除了写入一个新的函数）？

Answer 1

我从你的解释中提出plunkr here。看看它是否符合你的标准并解决你的问题。这里是总结：

private getCategories(): Observable<any>{ 
if(this.categoriesInLs){ 
    return Observable.of("categories data"); 
} else { 
    return this.searchService.getCategories(); 
} 
} 

private getResults(): Observable<any>{ 
    if(this.resultsInLs){ 
    return Observable.of("results data"); 
    } else { 
    return this.searchService.getResults(); 
    } 
} 

get(){ 
    this.getCategories() 
    .flatMap(categories => this.getResults()) 
    .subscribe(r => console.log(r)); 
}