How to eliminate a particular validator from a form group in Angular

My goal is to eliminate the specific validator from the validator array so that I can reconfigure the controls when certain values have changed.

I am aware of the traditional solution where I would need to repeatedly set validators.

checked(event: MatCheckboxClickAction): void {
    const control = (this.form.get(
        'information',
    ) as FormGroup).controls.data1;
    if (event) {
        this.updateRequiredValidator(control);
    } else {
        control.setValidators([
            Validators.maxLength(9), Validators.minLength(2)
        ]);
        control.updateValueAndValidity();
    }
}

updateRequiredValidator(control: AbstractControl): void {
    control.setValidators([
        Validators.required,
        ...(control?.validator ? [control?.validator as ValidatorFn] : []),
    ]);
    control.updateValueAndValidity();
}

Instead of repeatedly setting validators, I simply want to remove Validators.required on the else part.

Answer №1

If you are looking for the best approach, consider implementing a "customValidator" such as "requireIf".

  requiredIf(field: string) {
    return (control: FormControl):{required:boolean}|null => {
      const form = control.parent as FormGroup;
      const check=form?form.get(field):null
      if (form && check && check.value)
        return !control.value ? { required: true } : null;

      return null;
    };
  }
//example usage:
this.form=new FormGroup({
   check:new FormControl();
   data1:new FormControl(null,this.requiredIf('check'))
})

However, keep in mind that when the 'check' field changes, you will need to use

this.form.get('data1').updateValueAndValidity()

In the stackblitz example, I utilized mat-angular and used the (change) event to trigger updateValueAndValidity.

UPDATE: Ensure to define the type of the function

requiredIf(field: string):ValidatorFn {
    return (control: AbstractControl):{required:boolean}|null => {
      ....
    }
}

Answer №2

One way to streamline the process is to develop a custom validator function that checks for all potential errors and utilizes the setError method within the AbscractControl.

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Complicated "as-label" for understanding expressions in Angular

Is it possible to set a complex label in a comprehension expression in Angular? I've searched everywhere for a solution, but I can't seem to find one. The workaround I found involves pre-populating the 'as' label attribute with the des ...

Is it possible to simultaneously employ two asynchronous functions while handling two separate .json files?

Is it possible to work with 2 .json files simultaneously? My attempt did not succeed, so I am looking for an alternative method. If you have a suggestion or know the correct syntax to make this work, please share. And most importantly, does the second .j ...

Validating form field values in JavaScript prior to submission

My website features a search box that allows users to search through a database of books. When utilizing the search feature, users are presented with the following options: Search Query (a text input field) Where to search (a select field with the option ...

Guide to integrating the Braintree API with Node.js

I am trying to implement Braintree for website payment gateway, but I encountered an issue while following the online guidelines. The code seems to be incompatible with Node.js. Am I missing something? Index.js: //send token to clients app.get("/client_t ...

What is the best way to utilize a single AngularJS 1.5 component multiple times within a single view?

While working on a project using AngularJS 1.5's new components, I encountered an issue with widget isolation. It seems that when I use the same widget multiple times, they end up sharing their controller or scope. I was under the impression that comp ...

Typescript libraries built specifically for unique custom classes

I am currently exploring the most effective method for creating a class library in Typescript and deploying it to NPM along with a definitions file. The classes within the library serve as models that are utilized by multiple RESTful services. Some of the ...

What is the best way to organize nestedGroups in the vis.js timeline?

Running into an issue with the nestedGroups in my code. Despite sorting the array before creating the items and nestedGroups, I'm encountering a problem where the first item is showing up in the last position on the timeline. Attached is a screenshot ...

Embed the variable directly within the JSON structure

My goal is to dynamically create a JavaScript object using object initializer notation, but with keys taken from a config object. Instead of the traditional method: var obj = { 'key' : 'some value' }; I envision something like this: ...

Upon attempting to add a new component, an error was encountered: Uncaught SyntaxError: Unexpected token export

I have created a React test project and added modules to my package.json as follows: { "name": "untitled", "version": "0.1.0", "private": true, "devDependencies": { "babel-preset-node5": "^12.0.1", "react-scripts": "0.9.5" }, "depe ...

Filtering data from an Ajax request in Angular using a filter function with JSON

Hi everyone, I recently started learning AngularJS and created a basic item list with search functionality and pagination. Everything was working smoothly, so I decided to move my list outside the controller and store it as a JSON file. Here's what ...

Invoke a class method once the Promise has been successfully resolved

I'm facing an issue with my simple class class A{ constructor(){ this.loadComponents().then(function(values) {callbackOnLoad();}); } callbackOnLoad(){ //do some things } loadComponents(){ ... return Promise.all([p1,p2,p3,p4,p ...

Displaying text that follows the cursor on a JavaScript mouseover event

When I hover over the pin with my cursor, the text should move along with the mouse. However, the current position of the text is off and needs to be adjusted to be next to the pin. What is a more accurate way to calculate the correct position? var toolt ...

What is the best way to retrieve an object from a loop only once the data is fully prepared?

Hey, I'm just stepping into the world of async functions and I could use some help. My goal is to return an object called name_dates, but unfortunately when I check the console it's empty. Can you take a look at my code? Here's what I have ...

Guide on storing a promise response in an external object in VUE

I am currently working on integrating the higchart network graph in vue. Everything seems to be functioning properly with static data. However, when I attempt to retrieve data using axios, it fails to work. export default { data() { return { ne ...

Error in Angular 6: Unable to access the property 'runOutsideAngular' as it is undefined

After creating a nav-bar using the CLI with the following command: ng g @angular/material:material-nav --name=version-nav I imported it into my component as follows: <app-version-nav></app-version-nav> Unfortunately, I encountered this erro ...

What is the best time to initialize .env variables in a NodeJS application?

Building a NodeJS Express REST API with TypeScript requires loading environment variables using the dotenv package. In my code, I access the .env variables in two different files: index.ts, which serves as the entry point, and in a separate file called My ...

Adjust the counter by increasing or decreasing based on the selection or deselection of tags

Currently, I am utilizing Next.js to manage a question form that consists of multiple questions with multiple answers. Users have the option to select one or multiple tags for each question. When a user selects one or more tags to answer a question, it sho ...

Having issues with AngularJS rzslider failing to dispatch updated slider value

Hello, I am currently using the rzmodule/rzslider in AngularJS. However, after changing the slider to a specific range, the ng-modal is not returning the updated value. It keeps returning the initial value of 10000 that was configured initially. $scope.sl ...

Angular: When $scope variable is modified, a blank page issue arises

In my Angular application, I have a template called viewAll.html that is displayed after clicking on a link. This template fetches data via AJAX using scope variables. However, I encountered an issue where updating these scope variables through AJAX cause ...

Tips for updating model data when integrating jQuery Data tables with ASP.NET MVC

Managing a large amount of data returned from JSON can be complex. To tackle this, I am utilizing jQuery dataTable for sorting, filtering, and pagination purposes. The functionality is working seamlessly for sorting, searching, and paginating the data. H ...