State and Error Management in Angular Forms

  Managing form states and errors improves user experience and ensures data integrity.


Detailed Synopsis:


  • 1. Form States:

      Form states are accessed using theform.get('name')method, which returns a form control. This control has properties that indicate the field's state, such asinvalid, valid, touched, dirty, and pending.

    • invalid indicates if the field does not meet the defined validations.
    • valid indicates the opposite.
    • touched indicates if the user has interacted with the field.
    • dirty indicates if the field's value has changed since its initialization.
    • pending indicates if an asynchronous validation is in progress.
      
      Example:


  • 2. Error Handling:

      Form errors are stored in theerrors property of the form control. This property is an object that contains specific errors for each failed validation.
      To access a specific error, use the syntax form.get('name').errors?.errorName. The?. (optional chaining) operator ensures that no error occurs if errors is null or undefined.
      Examples of common errors: required, minlength, maxlength, pattern, email, etc.
      Example:

      Additionally, you can check for general errors with form.get('name').errors, which will return an object with all present errors, or null if there are no errors.


Purpose:


  • Improve user experience.
  • Ensure data integrity.
  • Provide user feedback.

Exercises


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How do you access the states of a form in Angular?