Implementing a Dynamic Form Group in Angular

This challenge focuses on building a reusable Angular component that dynamically generates a form group based on a provided configuration. Form groups are fundamental to Angular forms, allowing for structured data management and validation. Successfully completing this challenge will demonstrate your understanding of Angular forms, component design, and data binding.

Problem Description

You are tasked with creating an Angular component called DynamicFormGroupComponent. This component will accept an array of form control configurations as input and render a corresponding form group. Each configuration object will define the control's type (e.g., 'text', 'number', 'select'), name, label, and any validation rules. The component should dynamically create the form controls, apply the specified validations, and bind them to a form group. The component should also emit an event containing the form group's value when the form changes.

Key Requirements:

• Dynamic Control Creation: The component must dynamically create form controls based on the input configuration.
• Validation: The component must apply any specified validation rules to the form controls. For simplicity, assume validations are provided as an array of strings (e.g., ['required', 'minlength:5']).
• Data Binding: The component must bind the form controls to a form group and display the labels appropriately.
• Value Emission: The component must emit an event (formValues) containing the current value of the form group whenever the form changes.
• Reusability: The component should be designed to be reusable with different configurations.

Expected Behavior:

The component should render a form with the controls defined in the configuration. Each control should have a label and be appropriately styled. When a user interacts with the form, the formValues event should be emitted with the current form data. Validation errors should be displayed appropriately (though detailed error display is not required for this challenge - simply ensure the validations are applied).

Edge Cases to Consider:

• Empty configuration array: The component should render an empty form.
• Invalid control types: Handle unknown control types gracefully (e.g., by rendering a default text input or logging an error).
• Missing configuration properties: Handle missing properties (e.g., missing label) gracefully.
• Complex validation rules: While detailed error display isn't required, ensure the validations are applied correctly.

Examples

Example 1:

Input:
[
  {
    type: 'text',
    name: 'firstName',
    label: 'First Name',
    validation: ['required']
  },
  {
    type: 'email',
    name: 'email',
    label: 'Email',
    validation: ['required', 'email']
  }
]
Output:
A form with two fields: "First Name" (text input, required) and "Email" (email input, required).  Emits the form values as an object when the form changes.
Explanation: The component dynamically creates a text input for 'firstName' and an email input for 'email', applying the specified validations.

Example 2:

Input:
[
  {
    type: 'number',
    name: 'age',
    label: 'Age',
    validation: ['required', 'min:18']
  }
]
Output:
A form with a single field: "Age" (number input, required, minimum value of 18).  Emits the form values as an object when the form changes.
Explanation: The component creates a number input for 'age' and applies the required and min validations.

Example 3: (Edge Case - Empty Configuration)

Input: []
Output:
An empty form.
Explanation: The component handles the case where the configuration array is empty.

Constraints

• Angular Version: Angular 14 or higher.
• Reactive Forms: Must use Angular's Reactive Forms approach.
• Control Types: Support at least 'text', 'email', and 'number' control types. Other types can be handled as a default text input.
• Validation: Support 'required', 'email', 'minlength', and 'min' validations.
• Performance: The component should be reasonably performant even with a large number of controls (e.g., up to 20). Avoid unnecessary DOM manipulations.
• Output: The formValues event should emit an object where keys are the control names and values are the corresponding control values.

Notes

• Consider using FormBuilder to create the form group and controls.
• Use Validators from @angular/forms to implement the validations.
• Use ngOnChanges to react to changes in the input configuration.
• Think about how to handle different control types and their specific input types (e.g., type="email" for email inputs).
• Focus on the core functionality of dynamically creating and validating the form controls. Detailed styling and error display are not the primary focus of this challenge.
• The component should be a standalone component. No need to integrate it into a larger application.