[英]variable in component.ts not appearing in component.html angular2
I am trying to display a variable on my component.html that I have in my component.ts file. 我试图在我的component.ts文件中显示我的component.html上的变量。 Other variables are displaying but for some weird reason the number variable is not displaying.
其他变量正在显示,但由于一些奇怪的原因,数字变量未显示。 The issues I am having is bigger than this but this will help solve the larger problem.
我遇到的问题比这更大,但这将有助于解决更大的问题。 This is a link to the other question in case you would want to take a look at it: Displaying list one by one in angular2 .
这是另一个问题的链接,以防您想要查看它: 在angular2中逐个显示列表 。
Here is the .ts file 这是.ts文件
import { Http } from '@angular/http';
import { FormGroup, FormControl, Validators, FormBuilder } from '@angular/forms';
import { ToastComponent } from '../shared/toast/toast.component';
import { DataService } from '../services/data.service';
@Component({
selector: 'app-student',
templateUrl: './student.component.html',
styleUrls: ['./student.component.css']
})
export class StudentComponent implements OnInit {
questions = [];
isLoading = true;
currentQuestionNumber = 0;
question = {};
addQuestionForm: FormGroup;
name = new FormControl('', Validators.required);
a_Answer = new FormControl('', Validators.required);
b_Answer = new FormControl('', Validators.required);
c_Answer = new FormControl('', Validators.required);
d_Answer = new FormControl('', Validators.required);
a_Freq = new FormControl('', Validators.required);
b_Freq = new FormControl('', Validators.required);
c_Freq = new FormControl('', Validators.required);
d_Freq = new FormControl('', Validators.required);
constructor(private http: Http,
private dataService: DataService,
public toast: ToastComponent,
private formBuilder: FormBuilder) { this.currentQuestionNumber = 0}
ngOnInit() {
this.getQuestions();
this.currentQuestionNumber = 0;
this.addQuestionForm = this.formBuilder.group({
name: this.name,
a_Answer: this.a_Answer,
b_Answer: this.b_Answer,
c_Answer: this.c_Answer,
d_Answer: this.d_Answer,
a_Freq: this.a_Freq,
b_Freq: this.b_Freq,
c_Freq: this.c_Freq,
d_Freq: this.d_Freq
});
}
getQuestions() {
this.dataService.getQuestions().subscribe(
data => this.questions = data,
error => console.log(error),
() => this.isLoading = false
);
}
incrementFreqA(question) {
question.a_Freq = question. a_Freq + 1;
this.dataService.editQuestion(question).subscribe(
res => {
this.question = question;
},
error => console.log(error)
);
}
incrementFreqB(question) {
question.b_Freq = question. b_Freq + 1;
this.dataService.editQuestion(question).subscribe(
res => {
this.question = question;
},
error => console.log(error)
);
}
incrementFreqC(question) {
question.c_Freq = question. c_Freq + 1;
this.dataService.editQuestion(question).subscribe(
res => {
this.question = question;
},
error => console.log(error)
);
}
incrementFreqD(question) {
question.d_Freq = question. d_Freq + 1;
this.dataService.editQuestion(question).subscribe(
res => {
this.question = question;
},
error => console.log(error)
);
}
}
This is the .html file. 这是.html文件。 All questions are displayed with the Hello World after it but with no number 0 after it.
所有问题都显示在Hello World之后,但之后没有数字0。
<div class="card" *ngIf="isLoading">
<h4 class="card-header">Loading...</h4>
<div class="card-block text-xs-center">
<i class="fa fa-circle-o-notch fa-spin fa-3x"></i>
</div>
</div>
<div class="card" *ngIf="!isLoading">
<div class="card-block text-md-center" *ngFor="let question of questions; let i=index">
<form>
<fieldset class="form-group">
<h1>{{question.name}}</h1>
<div class="btn-group btn-group-lg" role="group" aria-label="Basic example">
<button type="button" class="btn btn-secondary" (click)="incrementFreqA(question)">{{question.a_Answer}}</button>
<button type="button" class="btn btn-secondary" (click)="incrementFreqB(question)">{{question.b_Answer}}</button>
<button type="button" class="btn btn-secondary" (click)="incrementFreqC(question)">{{question.c_Answer}}</button>
<button type="button" class="btn btn-secondary" (click)="incrementFreqD(question)">{{question.d_Answer}}</button>
<p>Hello World</p>
<p>{{currentQuestionNumber}}</p>
</div>
</fieldset>
</form>
</div>
</div>
Any help of pointers would be appreciated. 任何指针的帮助将不胜感激。
In your component you are having 在您的组件中
isLoading = true;
And your HTML contains this line 你的HTML包含这一行
<div class="card" *ngIf="!isLoading">
So, !isLoading== false
and your template is not rendered in the DOM 所以,
!isLoading== false
,你的模板不会在DOM中呈现
Also, you have below function 此外,你有以下功能
getQuestions() {
this.dataService.getQuestions().subscribe(
data => this.questions = data,
error => console.log(error),
() => this.isLoading = false
);
}
Note : When your subscription completes() then only this.isLoading=false
will execute. 注意:当您的订阅完成()时,只会执行
this.isLoading=false
。 It seems that you are not unsubscribing or your subscription never ends. 您似乎没有取消订阅或订阅永远不会结束。 So this line will not execute and your DOM is not rendered
所以这一行不会执行,你的DOM也不会被渲染
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