如何在Observable.bindCallback方法中使用RXJS选择器函数? [英] How do I use the RXJS selector function in the Observable.bindCallback method?

问题描述

我相信在使用Observable.bindCallback方法时，要使两个参数正确地映射回回调，您必须使用选择器"功能，但是我找不到解释该操作方法的文档.我可能对选择器功能的功能有误解，但仍应记录在案.

I believe that to get two params properly mapped back to the callback when using Observable.bindCallback method you have to use the "selector" function, but I cannot find documentation that explains how to do this. I may have a misunderstanding of what the selector function does, but it still should be documented.

http://reactivex.io/rxjs/class/es6/Observable.js〜Observable.html#static-method-bindCallback

function testLogin(username, password, callback){
    // ...
    callback(param1, param2);
}

function selectorFunction(???) {
    // ???
}

function onTestLoginComplete(param1, param2) {
     // ...
}

var observableFactory = Observable.bindCallback(testLogin, selectorFunction);
var observable = observableFactory('username', 'password');
observable.subscribe( (param1, param2) => onTestLoginComplete(param1, param2) );

推荐答案

subscribe函数只能接受单个参数.因此，selector函数是关于将多参数回调转换为单个元素.通常，这意味着您将把参数打包到一个对象中，然后可以在以后对其进行解构:

The subscribe function can only ever take a single argument. So the selector function is about converting a multiargument callback into a single element. In general this means that you will pack the arguments into an object, and you can destructure it later on:

function testLogin(username, password, callback){
    // ...
    callback(param1, param2);
}

//Convert this into a new object
function selectorFunction(param1, param2) {
    return {param1, param2};
}

function onTestLoginComplete(param1, param2) {
     // ...
}

var observableFactory = Observable.bindCallback(testLogin, selectorFunction);
var observable = observableFactory('username', 'password');
//De-structure the argument when it is passed to subscribe.
observable.subscribe( ({param1, param2}) => onTestLoginComplete(param1, param2) );

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