Question 1

How to add custom validation in Svelte Formly?

Accepted Answer

Extend the validation system by creating custom rule functions and integrating them into the field configuration. The library's documentation provides guidance on implementing custom validators, though it may require additional coding effort beyond the built-in rules.

Question 2

Svelte Formly vs svelte-forms-lib: which is better for dynamic forms?

Accepted Answer

Svelte Formly excels with its declarative JSON approach for dynamic, configurable forms, reducing boilerplate. In contrast, svelte-forms-lib offers more imperative control; choose Svelte Formly for rapid prototyping and complex forms, while svelte-forms-lib suits simpler, programmatic needs.

Question 3

How to handle form submission in Svelte Formly?

Accepted Answer

Use the on:submit event listener as shown in the example to capture form data. The detail property in the event contains the submitted values, which you can process or send to an API.

Question 4

Can I use Svelte Formly with SvelteKit?

Accepted Answer

Yes, Svelte Formly is compatible with SvelteKit since it's built for Svelte. Install it via npm and use it in SvelteKit components, similar to the provided usage example with TypeScript support.

Question 5

How to style forms in Svelte Formly?

Accepted Answer

Apply CSS by setting classes in the attributes.classes property of field configurations or using global styles. The library doesn't include pre-styled components, so custom CSS is necessary for design.

Question 6

Is Svelte Formly good for multi-step forms?

Accepted Answer

Yes, it supports multi-step forms through dynamic field updates and reactive configurations. You can manage step logic by modifying the fields array based on user interactions, though this may require additional state management.

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