MongoDB via Mongoose JS - What is findByID?

Question

I am writing a NodeJS server with ExpressJS, PassportJS, MongoDB and MongooseJS. I just managed to get PassportJS to use user data obtained via Mongoose to authenticate.

But to make it work, I had to use a "findById" function like below.

var UserModel = db.model('User',UserSchema);

UserModel.findById(id, function (err, user) { < SOME CODE > } );

UserModel is a Mongoose model. I declare the schema, UserSchema earlier. So I suppose UserModel.findById() is a method of the Mongoose model?

Question

What does findById do and is there documentation on it? I googled around a bit but didn't find anything.

JohnnyHK · Accepted Answer · 2018-10-30T18:51:48.043

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findById is a convenience method on the model that's provided by Mongoose to find a document by its _id. The documentation for it can be found here.

Example:

// Search by ObjectId
var id = "56e6dd2eb4494ed008d595bd";
UserModel.findById(id, function (err, user) { ... } );

Functionally, it's the same as calling:

UserModel.findOne({_id: id}, function (err, user) { ... });

Note that Mongoose will cast the provided id value to the type of _id as defined in the schema (defaulting to ObjectId).

edited Oct 30 '18 at 18:51

answered Sep 18 '12 at 19:34

JohnnyHK

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what's the data type of id? is it a string or an ObjectId? – bubakazouba Jan 11 '16 at 03:09
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@bubakazouba `id` will be cast to whatever type `_id` is defined as in the schema (defaults to `ObjectId`). – JohnnyHK Apr 05 '16 at 15:02
anybody know if there is a removeById convenience method as well? – Alexander Mills Feb 24 '17 at 00:50
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@AlexanderMills There is. It is called `findByIdAndRemove` – Babalola Rotimi Jun 11 '17 at 19:56

score 9 · Answer 2 · answered May 23 '18 at 06:56

9

If the schema of id is not of type ObjectId you cannot operate with function : findbyId()

answered May 23 '18 at 06:56

Dasikely

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score 7 · Answer 3 · answered Jan 28 '14 at 23:25

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As opposed to find() which can return 1 or more documents, findById() can only return 0 or 1 document. Document(s) can be thought of as record(s).

answered Jan 28 '14 at 23:25

Bonnie Varghese

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score 4 · Answer 4 · answered Sep 11 '19 at 15:53

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I'm the maintainer of Mongoose. findById() is a built-in method on Mongoose models. findById(id) is equivalent to findOne({ _id: id }), with one caveat: findById() with 0 params is equivalent to findOne({ _id: null }).

You can read more about findById() on the Mongoose docs and this findById() tutorial.

answered Sep 11 '19 at 15:53

vkarpov15

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I am getting the following error: `{ "message": "Cast to ObjectId failed for value \"{ id: '5d9a3b073f308e32b47a5cbb' }\" at path \"_id\" for model \"Categories\"", "name": "CastError", "stringValue": "\"{ id: '5d9a3b073f308e32b47a5cbb' }\"", "kind": "ObjectId", "value": { "id": "5d9a3b073f308e32b47a5cbb" }, "path": "_id" }` – Jasim Khan Afridi Oct 06 '19 at 20:15
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Looks like you're passing in an object with an `id` property rather than a string or ObjectId instance. Try printing out `typeof val` and `val.constructor.name` to check what type you're actually passing in to `findById()` – vkarpov15 Oct 09 '19 at 16:08
I tried many combinations. Or may I say, all combinations. I do no have a property named `id`. I do no have the property of type `ObjectId`. – Jasim Khan Afridi Oct 11 '19 at 13:29
ok. found out my mistake. it was a silly one. i was passing id object as { id: 'blablabla' } instead of string... – Jasim Khan Afridi Oct 12 '19 at 22:43
@vkarpov15 Where can I find source of this `findById`? – rofrol Dec 10 '21 at 17:48

MongoDB via Mongoose JS - What is findByID?

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