Why findOneAndUpdate runs .then even if returned object was null? Mongoose

Question

This is my code:

User.findOneAndUpdate(
    { confirmationToken: "blablabla" },
    { confirmationToken: "", confirmed: true },
    { new: true }
    )
    .then(user => res.json({ user: user.toAuthJSON() }) )
    .catch(err => res.json({ err }));
)

When there isn't any user with such confirmationToken, findOneAndUpdate returns null but why it runs .then instead of .catch? Shloudn't it run .then when user is returned and run .catch when returned is NULL instead of user object?

Answer 1

Returning null is valid response. To protect your code from that you could:

User.findOneAndUpdate(
    { confirmationToken: "blablabla" },
    { confirmationToken: "", confirmed: true },
    { new: true }
    )
    .then(user => res.json({ user: user ? user.toAuthJSON() : user }) )
    .catch(err => res.json({ err }));
)

Or you could throw inside your .then if hitting the catch is what you really want.

As per mongoose docs on Model.findOneAndUpdate :

Finds a matching document, updates it according to the update arg, passing any options, and returns the found document (if any) to the callback.

Answer 2

当发生错误时， catch运行，例如：猫鼬验证错误或您想要更新集合中的文档而发生一些错误。