How can I manually set an Angular form field as invalid?

🔑💻💡 How to Manually Set an Angular Form Field as Invalid 🚫👨‍💻

Are you working on a login form and struggling to mark the email and password fields as invalid when the user enters incorrect credentials? Don't worry, we've got you covered! In this blog post, we'll walk you through the steps to manually set an Angular form field as invalid. Let's dive in! 🏊‍♀️💦

🔎 Understanding the Problem: The goal is to mark both the email and password fields as invalid and display a message when the login fails. The challenge lies in triggering the invalid state of the form fields from an observable callback.

💡 Easy Solutions: 1️⃣ Method 1: Using the "invalid" Property In your login method, you can set the "invalid" property of the form field controls to true. Here's an example:

@ViewChild('loginForm') loginForm: HTMLFormElement;

private login(formData: any): void {
  this.authService.login(formData).subscribe(res => {
    alert("Congrats, you have logged in. We don't have anywhere to send you right now though, but congrats regardless!");
  }, error => {
    this.loginFailed = true; // Display error message
    this.loginForm.controls.email.invalid = true; // Set email field as invalid
    this.loginForm.controls.password.invalid = true; // Set password field as invalid
  });
}

2️⃣ Method 2: Updating the "valid" State Additionally, you may also try setting the "valid" flag of the email and password fields to false. While this solution may not trigger the visual invalid state, it can still be useful for form validation and submission handling.

3️⃣ Method 3: Setting the "invalid" State of the Form If you want to mark the entire form as invalid, you can set the "invalid" property of the form itself to true. However, keep in mind that this approach won't visually highlight the individual fields as invalid.

👨‍💻 Examples and Explanations: In the provided code snippet, you can see the template of the login form. Notice the "md-input-container" and "input" elements for the email and password fields, respectively.

To manually set the email and password fields as invalid, use the "invalid" property of the form field controls within the login method. By setting them to true, you'll trigger the invalid state and display the error message accordingly.

🚦 Troubleshooting: If you've tried the above solutions and the inputs are still not displaying their invalid state, there might be other factors affecting this behavior. Make sure to check for any custom styles or CSS classes that override the default Angular form field validation styles.

📢 Call-to-Action: Now that you know how to manually set an Angular form field as invalid, go ahead and implement it in your project. If you have any questions or issues, feel free to reach out to us or leave a comment below. Happy coding! 💻🎉

#angular #form-validation #invalid-state #programming #techblog