Data binding checkboxes in svelte - forms

Question

in a svelte/sapper form I want to send data to a user model
<input type="text" bind:value={user.label}>
..works as expected. But how to send user.offer_ids
let offer_ids = [];
{#each offers as offer}
<label>
<input type=checkbox bind:group={offer_ids} value="{offer.id}">{offer.label}
</label>
{/each}
I can't find any svelte sample how to do this job, which I think is basic in forms.. Thanks for help
May be it was unclear..I want to send data to Json:
<form>
<input type="text" bind:value={user.label}> //gives data to 'user'
{#each offers as offer}
<label>
<input type=checkbox bind:group={offer_ids} value="{offer.id}">{offer.label}
</label>
{/each}
//how to get all selected ids to 'user'
</form>
Hope this is more clear now.

Answer 1

With checkboxes, we bind to checked instead of value:
<script>
let name = 'world';
let flag = false
</script>
<style>
.highlighted {
color: red
}
</style>
<h1 class:highlighted={flag}>Hello {name}!</h1>
<label for="checkbox">Highlight header</label>
<input id="checkbox" type='checkbox' bind:checked={flag}/>
Edit
The offer model should have a selected or checked state. Then you can bind the checkbox to that:
<script>
let name = 'world';
let offers = [
{id: 1, name: 'One', checked: false},
{id: 2, name: 'Two', checked: false},
{id: 3, name: 'Three', checked: false},
]
</script>
{#each offers as offer, index (offer.id)}
<label for={'checkbox'+offer.id}>{offer.name}</label>
<input id={'checkbox'+offer.id} bind:checked={offer.checked} type='checkbox'/>
{/each}
<div>
{offers.filter(offer => offer.checked).map(offer => offer.name)}
</div>
Here, we display three checkboxes and the text below prints the names of the selected offers on the screen.
REPL: https://svelte.dev/repl/461fea432dc54ed0a744afc4e05bf34b?version=3.22.3

Answer 2

so my solution now:
let offer_ids = [];
<form>
{#each offers as offer, i (offer.id)}
<label>
<input type=checkbox bind:group={offer_ids} value="{offer.id}">{offer.label}
</label><br/>
{/each}
</form>
enter code here
and in the function...
async function publish() {
user.offer_ids = offer_ids
const response = await (api.post('users', {user}));