小编Koe*_*uck的帖子

我正在我的Angular 2应用程序中构建一个搜索框,尝试在点击"Enter"时提交值(表单不包含按钮).

模板

<input type="text" id="search" class="form-control search-input" name="search" placeholder="Search..." [(ngModel)]="query" (ngSubmit)="this.onSubmit(query)">

使用简单的onSubmit函数进行测试......

export class HeaderComponent implements OnInit {
  constructor() {}

  onSubmit(value: string): void {
    alert('Submitted value: ' + value);
  }
}

在这种情况下,ngSubmit似乎不起作用.那么解决这个问题的'Angular 2方式'是什么？(最好没有像隐藏按钮这样的黑客)

我正在构建一个Angular 2应用程序,它有一个侧导航栏,用于宽度超过500的屏幕,以及一个底部导航栏,用于宽度小于500的屏幕.现在我试图为侧栏指定20%的宽度,80 %到应用内容.

我遇到的问题是路由器插座内容(即实际的应用程序)占用了页面的整个宽度而不是80%.它似乎忽略了我试图给它的任何造型.我们不应该直接设置路由器插座的样式吗？或者也许有一种更好的方式让我俯瞰？

app.component.ts

import { Component, HostListener } from '@angular/core';

@Component({
  selector: 'my-app',
  template: `
    <div class="container-fluid">
      <nav *ngIf="this.window.innerWidth > 500"></nav>
      <router-outlet style="width:80%;float:right;"></router-outlet>
      <nav *ngIf="this.window.innerWidth < 500"></nav>
  `,
  styleUrls: ['app/app.component.css']
})
export class AppComponent {
  window = [];

  ngOnInit(): void {
    this.window.innerWidth = window.innerWidth;
  }

  @HostListener('window:resize', ['$event'])
  onResize(event) {
    this.window.innerWidth = event.target.innerWidth;
    console.log(this.window.innerWidth);
  }
}

考虑Python中的以下实例行为.

def change(elements):
    elements[0] = 888
    elements = [-3, -1, -2, -3, -4]
    print(elements[0])

numbers = [1, 4, 5]

print(numbers[0])
change(numbers)
print(numbers[0])
print(numbers)

下面的Python代码段打印出来

1
-3, 
888 
[888,4,5]

不应该打印

1, 
-3, 
-3, 
[-3,-1,-2,-3,-4]

为什么列表中的元素会被成功覆盖,而不是整个列表对象？

I have a huge bucket of S3files that I want to put on HDFS. Given the amount of files involved my preferred solution is to use 'distributed copy'. However for some reason I can't get hadoop distcp to take my Amazon S3 credentials. The command I use is:

hadoop distcp -update s3a://[bucket]/[folder]/[filename] hdfs:///some/path/ -D fs.s3a.awsAccessKeyId=[keyid] -D fs.s3a.awsSecretAccessKey=[secretkey] -D fs.s3a.fast.upload=true

However that acts the same as if the '-D' arguments aren't there.

ERROR tools.DistCp: Exception encountered
java.io.InterruptedIOException: doesBucketExist on [bucket]: com.amazonaws.AmazonClientException: …

为什么 IntelliJ 抱怨它无法解析以下代码片段中的符号“字段”？

  val condition: String = "aa"

  if (condition == "aa") {
    val fields: Int = 2
  } else if (condition == "bb") {
    val fields: Int = 3
  } else if (condition == "cc") {
    val fields: Int = 4
  }

  var g = 1
  while (g < fields) { 
     //do something
     g = g + 1
  }

以下代码段在'fields.size'处失败:"值大小不是Any的成员".为什么"字段"不是"列表"类型(正如我所料)？

val condition = "a"
val fields =
    if (condition == "a") {
      List(1,2)
    } else if (condition == "b") {
      List(1,2,3)
    } else if (condition == "c") {
      List(1,2,3,4)
    }

  var g = 1
  while (g < fields.size) {
    //do something
    g = g + 1
  }