Necessary CSS selector input equivalent in Reactive Forms

Question

Necessary CSS selector input equivalent in Reactive Forms

Is there a similar CSS method like input:required {CSS} to style all the reactive form fields in Angular that are set as required using Validators.required in their formControl? Or is there another approach to achieve this with CSS?

angular css angular-reactive-forms

Answer 1

Answer №1

UPDATE 2 (working)

Unfortunately, Angular does not offer a direct solution for retrieving the validators of a FormControl. This means that developers often have to resort to somewhat unconventional methods to achieve this.

Currently, one common workaround involves iterating through the FormControls, executing the validators on an empty control:

const validator = abstractControl.validator({}as AbstractControl);
            if (validator && validator.required) {
                return true;
            }

This method checks if the required validator is present. While it does function as intended, it executes all synchronous validators. Additionally, it allows developers to access the nativeElements of the form controls and compare them using formControlName.

To demonstrate this approach, I have created a StackBlitz example: https://stackblitz.com/edit/angular-hifypw?file=src%2Fapp%2Fapp.component.ts

In this demonstration, any required FormControl will be visually highlighted with a red background. Using template variables like theForm, developers can access the Element containing the FormGroup and select each child element of type input. They can then iterate over these elements to check for the presence of the required validator by comparing them based on formControlName.

 const controls =  this.getValidators(this.frmMain.controls);
      this.elements.forEach(x => {
            x.nativeElement.querySelectorAll('input').forEach(i => {

              const c = controls[i.attributes['formcontrolname'].value];

              if(i.attributes['formcontrolname'] && c && c.required && !i.classList.contains('test')) {
                i.classList.add('test');
              }

            });
    })

While this workaround proves effective, it may seem overly complex for such a simple task. Furthermore, this approach currently only functions within the same component and may not be compatible with Ahead-of-Time (AOT) compilation.

Although functional, I believe utilizing a custom directive or a straightforward CSS class would be more efficient in addressing this issue.

UPDATE

At the moment, the only viable solution appears to involve manually creating a class called .required and adding it to affected elements.

Alternatively, a combination of @ViewChildren and FormControl might provide a solution, albeit with some level of complexity.

BELOW ONLY WORKS FOR TEMPLATE DRIVEN FORMS

An alternate approach could involve using selectors like input[type=text][required] for styling purposes.

However, implementing such a broad selector could potentially lead to complications later in the project, resulting in convoluted CSS rules to manage this issue. Creating a specific CSS class like .form-control[required], similar to frameworks like Bootstrap, may offer a more elegant solution.

Considerations must also be made for styling radio buttons and checkboxes, which require unique treatment compared to text fields and select boxes. For instance, certain styling properties may not apply uniformly across different input types.

For a more streamlined approach, developers could simply create a generic css class like .required to maintain separation from Angular-specific implementations.

Answer 2

UPDATE 2 (working)

Unfortunately, Angular does not offer a direct solution for retrieving the validators of a FormControl. This means that developers often have to resort to somewhat unconventional methods to achieve this.

Currently, one common workaround involves iterating through the FormControls, executing the validators on an empty control:

const validator = abstractControl.validator({}as AbstractControl);
            if (validator && validator.required) {
                return true;
            }

This method checks if the required validator is present. While it does function as intended, it executes all synchronous validators. Additionally, it allows developers to access the nativeElements of the form controls and compare them using formControlName.

To demonstrate this approach, I have created a StackBlitz example: https://stackblitz.com/edit/angular-hifypw?file=src%2Fapp%2Fapp.component.ts

In this demonstration, any required FormControl will be visually highlighted with a red background. Using template variables like theForm, developers can access the Element containing the FormGroup and select each child element of type input. They can then iterate over these elements to check for the presence of the required validator by comparing them based on formControlName.

 const controls =  this.getValidators(this.frmMain.controls);
      this.elements.forEach(x => {
            x.nativeElement.querySelectorAll('input').forEach(i => {

              const c = controls[i.attributes['formcontrolname'].value];

              if(i.attributes['formcontrolname'] && c && c.required && !i.classList.contains('test')) {
                i.classList.add('test');
              }

            });
    })

While this workaround proves effective, it may seem overly complex for such a simple task. Furthermore, this approach currently only functions within the same component and may not be compatible with Ahead-of-Time (AOT) compilation.

Although functional, I believe utilizing a custom directive or a straightforward CSS class would be more efficient in addressing this issue.

UPDATE

At the moment, the only viable solution appears to involve manually creating a class called .required and adding it to affected elements.

Alternatively, a combination of @ViewChildren and FormControl might provide a solution, albeit with some level of complexity.

BELOW ONLY WORKS FOR TEMPLATE DRIVEN FORMS

An alternate approach could involve using selectors like input[type=text][required] for styling purposes.

However, implementing such a broad selector could potentially lead to complications later in the project, resulting in convoluted CSS rules to manage this issue. Creating a specific CSS class like .form-control[required], similar to frameworks like Bootstrap, may offer a more elegant solution.

Considerations must also be made for styling radio buttons and checkboxes, which require unique treatment compared to text fields and select boxes. For instance, certain styling properties may not apply uniformly across different input types.

For a more streamlined approach, developers could simply create a generic css class like .required to maintain separation from Angular-specific implementations.

Necessary CSS selector input equivalent in Reactive Forms

Answer №1

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