Tips for composing content on a sanitized input?

Question

Tips for composing content on a sanitized input?

In my small application, I have a feature where a question is displayed with certain words hidden and needs to be filled in by the user. The format of the question looks like this:

 The {0} {1} {2} his {3} off

To achieve this functionality, I wrote the following code:

HTML section

<div *ngFor="let question of questionsArray">
     ---- some content here ----
    <div [innerHTML]="createQuestion(question)"></div>
     ---- some content here ----
</div>

Typescript function:

createQuestion(question: string): SafeHtml {
    let innerHtml = '';
    let words = question.split(' ');

    for (let index = 0; index < words.length; index++) {
        const element = words[index];
        if (element.indexOf('{') >= 0) {
            innerHtml += '<input type="text" name="test"></input>';
        } else {
            innerHtml += element;
        }
    }

    return this.sanitizer.bypassSecurityTrustHtml(innerHtml);
}

I have also included the DomSanitizer in the constructor as shown below:

 constructor(private sanitizer: DomSanitizer) {}

Although the inputs are being rendered correctly, I am facing an issue where I am unable to type anything in the input field. I suspect that the bypassSecurityHtml method might not be working correctly without using a Pipe as suggested here. Since the dynamic creation of inputs based on each question prevents me from using it within a pipe, I am seeking assistance on how to resolve this issue...

If anyone could provide some guidance, it would be greatly appreciated.

angular typescript html-sanitizing

Answer 1

Answer №1

One issue with DOM strings is that Angular does not recognize them as part of the template for view binding, despite being rendered by the browser. To address this problem, a solution is to utilize an array to define how the template should be rendered, as demonstrated below:

createQuestion(question: string) {
const template = question.match(/[A-Za-z]+|{\d}/g)
                  .map(match => match[0] === '{' ? { type: 'input', value: ''}
                  : { type: 'string', value: match })

return template;
}

The createQuestion function takes a template string and breaks it down into segments using a regular expression method. Each segment is then transformed into a uniform object structure - placeholders for input are converted to { type: 'input', value: '' }, while text segments become

{ type: 'text', value: 'text value here' }

. This allows for conditional rendering of either text or input using *ngIf directives later on.

For instance, for the provided exemplary string, the following template is generated:

template = [
  { type: 'text', value: 'The' },
  { type: 'input', value: '' }
  { type: 'input', value: '' }
  { type: 'input', value: '' }
  { type: 'text', value: 'his' }
  { type: 'input', value: '' }
  { type: 'text', value: 'off' }
]

This template can then be utilized to create an angular template with bound values:

<div *ngFor="let template of questionsArray.map(q => createQuestion(q))">
     ---- some stuff ----
    <div *ngFor="let section of template">
    <input *ngIf="section.type === 'input'" ([ngModel])="section.value" />
    <span *ngIf="section.type === 'text'">{{ section.value }}</span>
    </div>
     ---- some stuff ----
</div>

The outer *ngFor loop iterates through all the transformed templates derived from different questions using .map(q => createQuestion(q)). The inner *ngFor loop cycles through each section of the template and displays either a span or an input based on the type property of each section. If the type is text, a span is displayed. If the type is input, an input field is displayed with ngModel linking to the value property.

Answer 2

One issue with DOM strings is that Angular does not recognize them as part of the template for view binding, despite being rendered by the browser. To address this problem, a solution is to utilize an array to define how the template should be rendered, as demonstrated below:

createQuestion(question: string) {
const template = question.match(/[A-Za-z]+|{\d}/g)
                  .map(match => match[0] === '{' ? { type: 'input', value: ''}
                  : { type: 'string', value: match })

return template;
}

The createQuestion function takes a template string and breaks it down into segments using a regular expression method. Each segment is then transformed into a uniform object structure - placeholders for input are converted to { type: 'input', value: '' }, while text segments become

{ type: 'text', value: 'text value here' }

. This allows for conditional rendering of either text or input using *ngIf directives later on.

For instance, for the provided exemplary string, the following template is generated:

template = [
  { type: 'text', value: 'The' },
  { type: 'input', value: '' }
  { type: 'input', value: '' }
  { type: 'input', value: '' }
  { type: 'text', value: 'his' }
  { type: 'input', value: '' }
  { type: 'text', value: 'off' }
]

This template can then be utilized to create an angular template with bound values:

<div *ngFor="let template of questionsArray.map(q => createQuestion(q))">
     ---- some stuff ----
    <div *ngFor="let section of template">
    <input *ngIf="section.type === 'input'" ([ngModel])="section.value" />
    <span *ngIf="section.type === 'text'">{{ section.value }}</span>
    </div>
     ---- some stuff ----
</div>

The outer *ngFor loop iterates through all the transformed templates derived from different questions using .map(q => createQuestion(q)). The inner *ngFor loop cycles through each section of the template and displays either a span or an input based on the type property of each section. If the type is text, a span is displayed. If the type is input, an input field is displayed with ngModel linking to the value property.

Answer 3

Answer №2

Using Angular in this way is not recommended.

Angular is designed to manage the DOM manipulation for you, so it's best to let the framework handle that task.

If you're facing an issue, consider using a pipe on your original string instead of directly modifying it.

Check out this live demo on Angular to see it in action

Answer 4

Using Angular in this way is not recommended.

Angular is designed to manage the DOM manipulation for you, so it's best to let the framework handle that task.

If you're facing an issue, consider using a pipe on your original string instead of directly modifying it.

Check out this live demo on Angular to see it in action

Answer 5

Answer №3

After reviewing the purpose of @Avin Kavish, I have discovered a straightforward solution:

Typescript segment

createQuestion(question: QuestionDto): Array<string> {
    let words = question.correctAnswer.split(' ');
    return words;
}

This function returns an array of strings with each element separated. The output looks like this:

["The", "{0}", "{1}", "{2}", "his", "{3}", "off"]

HTML section For the user interface, I examine the content array to determine whether to display an input field or the text.

<div *ngFor="let question of questionsArray">
    <div *ngFor="let word of createQuestion(question); index as i">
       <input *ngIf="word.includes('{'); else elseBlock"
           id="word-{{i}}"
           class="form-control"
           type="text" />
           <ng-template #elseBlock>{{ word }}</ng-template>
    </div> 
 </div>

Answer 6

After reviewing the purpose of @Avin Kavish, I have discovered a straightforward solution:

Typescript segment

createQuestion(question: QuestionDto): Array<string> {
    let words = question.correctAnswer.split(' ');
    return words;
}

This function returns an array of strings with each element separated. The output looks like this:

["The", "{0}", "{1}", "{2}", "his", "{3}", "off"]

HTML section For the user interface, I examine the content array to determine whether to display an input field or the text.

<div *ngFor="let question of questionsArray">
    <div *ngFor="let word of createQuestion(question); index as i">
       <input *ngIf="word.includes('{'); else elseBlock"
           id="word-{{i}}"
           class="form-control"
           type="text" />
           <ng-template #elseBlock>{{ word }}</ng-template>
    </div> 
 </div>

Tips for composing content on a sanitized input?

Answer №1

Answer №2

Answer №3

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