Question

我有一些布尔变量，可以是true或false，基于该值，我必须在HTML中显示一些元素，如下所示：

<p *ngif=isOwner>Test</p>

问题是我必须要隐藏元素值是false但显示元素值是true：

this.storage.get('User').then((val) => {
    this.isOwner = val.Owner.IsOwner;
});

在Angular 2中这样做的正确方法是什么，只是在HTML中，值总是存在，并且会是真还是假？

Answer 1

只需反转条件的布尔值：

See live stackblitz

%matplotlib inline
import pandas as pd
import numpy as np
import matplotlib
import matplotlib.pyplot as plt
from IPython.display import display
matplotlib.style.use('ggplot')

file = r'C:\Users\G01024822\Desktop\products.xlsx'
sheet = r'store_data'
data = pd.read_excel(file,sheetname=sheet,na_values='')
quarters = ['2018 Q1','2018 Q2','2018 Q3','2018 Q4','2019 Q1','2019 Q2','2019 Q3','2019 Q4','2020 Q1','2020 Q2','2020 Q3','2020 Q4']
categories = ['Windows','Office','Adobe']
stores = data['store'].unique().tolist()

mydata = {}
plandata = {}

for store in stores:
    transaction = data[data['Store']==store]

    for category in categories:
        frame = transaction[transaction['Category']==category]
        cycle = {}
        if frame.shape[0] != 0:
            for quarter in quarters:
                temp = frame[frame['License_ends']==quarter]
                out_of_licence = temp['Item'].count()
                cycle[quarter] = out_of_licence



        else:
            pass

        mydata[category] = cycle
        df = pd.DataFrame.from_dict(mydata,orient='index')

df

HTML

export class AppComponent  {
  public isOwner: boolean = true;
  toggleIsOwner() {
    this.isOwner = !this.isOwner; 
  }
}

<button (click)="toggleIsOwner()">show/hide</button> <p *ngIf="isOwner">Hello World!</p>是一个布尔值。 *ngIf的工作方式是，当表达式为true时，元素将插入DOM中，当表达式为false时，元素将从DOM中删除。

根据值Angular 2

1 个答案: