How can i update product variants? Please help me

I have developed a shopify app. The app feature is to update the product variables using product update metafiled
My demo code is bellow :

export const action = async ({ request }) => {

const { admin, session } = await authenticate.admin(request);
const prodiuctData = Object.fromEntries(await request.formData());

const product = await admin.rest.resources.Product.find({
session: session,
id: prodiuctData.productID,
});

product.variants = [
{
id: parseInt(prodiuctData.variantValue),
inventory_quantity: parseInt(prodiuctData.variantValue),
},
];

await product.save({
update: true,
});

console.log(product);

return json(null);
};

Can anyone please help me.