服务的角度2值在订阅功能之外不可用 [英] Angular 2 value from service not available outside subscribe function

问题描述

在我的组件中，我具有以下保存功能:

In my component I have a save function like below:

save() {
    var result;
    //For updating task
    if (this.task.AllTaskId) {
        if (this.task.AssignedToCode == null) {
            this.task.AssignedToCode = "All";
        }
        this.task.CreatedDate = new Date();

        this.task.CreatedBy = this.empcode;
        result = this._tasksService.updateTask(this.task).subscribe(
            res => {
                this._router.navigate(['/regtask'])
            }
        )
    }
    //For Adding new task
    else {
        if (this.task.AssignedToCode == null) {
            this.task.AssignedToCode = "All";
        }
        this.task.CreatedDate = new Date();
        this._tasksService.addTask(this.task)
            .subscribe((ntask) => {
                this.emitntask.emit(ntask);
                this._router.navigate(['/regtask']);
                this.temp = ntask.allTaskId;
                console.log(this.temp);
            })
        debugger;
        console.log(this.temp);
    }

    this.compform.reset();
}

如果查看save函数的else条件，当我在.subscribe()函数中记录值temp时，它将向我显示日志中的值，但是当我尝试在.subscribe之外记录相同的值时()函数，它向我显示了一个未定义的值，如下所示:

If you look at the else condition of the save function, When I log the value temp in the .subscribe() function, it shows me the value in my log but when I try to log the same value outside the .subscribe() function, it shows me an undefined value like below:

有人可以建议我怎么做，为什么.subscribe函数中的'this.temp'对我来说不可用?

Can anyone suggest me what to do and why 'this.temp' gets unavailable while it is available to me in .subscribe function?

推荐答案

这是因为传递给 subscribe()的回调是 ASYNCHRONOUSLY .

That's because the callback you pass to subscribe() is run ASYNCHRONOUSLY.

尝试运行以下代码:

// Some observable that takes a little while to complete (could be an HTTP request).
const obs = Observable.interval(200).first();

// Some callback that you want to execute when the obs emits/completes.
const callback = (val) => console.log('callback');

// Subscribe and log to console right after subscribing.
obs.subscribe(callback);
console.log('after subscribe');

您将在控制台中看到它:

You will see this in the console:

"after subscribe"
"callback"

该回调将在 obs.subscribe()之后的代码 AFTER 之后运行.

The callback is run AFTER the code that comes right after obs.subscribe().

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