Form implementation only allows flat objects

[ebetulo]

Onbezorgd Ontslag backend has a POSt route that requires data in a certain shape:

curl --request POST \
    "https://admin.onbezorgd-ontslag.igne.link/api/cases/9e3fcaa1-3b0c-4572-89c8-dbb003d10f4c/contact-persons" \
    --header "Authorization: Bearer {TOKEN}" \
    --header "Content-Type: application/json" \
    --header "Accept: application/json" \
    --data "{
    \"contact_persons\": [
        {
            \"id\": \"c2d28dff-2155-48df-b3bb-e3349223ee88\",
            \"first_name\": \"Jan\",
            \"infix\": \"van der\",
            \"last_name\": \"Veen\",
            \"job_title\": \"CEO\",
            \"email\": \"jan@example.com\",
            \"phone_number\": \"0612345678\"
        }
    ]
}"

There is no way to map the shape of the data returned by a form submit event before it got passed to the validator. We could either validate the flat structure and map it after validating but before posting, but we decided to allow a transform function as part of the form that runs on the data before validation. We solved it with the following code:

export const deepenFlatObject = (data: object): object => {
	return Object.entries(data).reduce((acc, [key, value]) => {
		const path = key.split(".");
		let target = acc;
		for (let i = 0; i < path.length - 1; i++) {
			const key = path[i];
			const isArray = /^\d+$/.test(path[i + 1]);
			target[key] ??= isArray ? [] : {};
			target = target[key];
		}
		// biome-ignore lint/style/noNonNullAssertion: Last item is always defined
		target[path.at(-1)!] = value;
		return acc;
		// biome-ignore lint/suspicious/noExplicitAny: We know what we're doing
	}, {} as any);
};

It would be nice if we had a standard implementation for this in the template.

[igne-wouter]

Good point.

I'm unsure if this is something we actually want to happen in forms? This is what react-zorm did for us, but that package had its issues so we moved away from it.

As for a implementation, we might want to depend on dot-object, which does this (among other things) and is a little more battle-tested.

@publicJorn What do you think?