What does REF mean in Mongoose?

What does REF mean in Mongoose?

ref basically means that mongoose would store the ObjectId values and when you call populate using those ObjectIds would fetch and fill the documents for you. So in this case: stories: [{ type: Schema. Types. ObjectId, ref: ‘Story’ }]

Is Mongoose ObjectId unique?

yes, the unique: true index guarantees it “in this one collection” – the algorithm “almost” guarantees it universally.

What does find by id return Mongoose?

Mongoose | findById() Function The findById() function is used to find a single document by its _id field. The _id field is cast based on the Schema before sending the command.

What is object ID in Mongoose?

An ObjectID is a 12-byte Field Of BSON type. The first 4 bytes representing the Unix Timestamp of the document. The next 3 bytes are the machine Id on which the MongoDB server is running. The next 2 bytes are of process id. The last Field is 3 bytes used for increment the objectid.

What is populate mongoose?

populate() function in mongoose is used for populating the data inside the reference. In your example StorySchema is having _creator field which will reference to the _id field which is basically the ObjectId of the mongodb document. populate() function can accept a string or an object as an input.

What is __ V in MongoDB?

Posted On: Jun 24, 2021. In Mongoose the “_v” field is the versionKey is a property set on each document when first created by Mongoose. This is a document inserted through the mongo shell in a collection and this key-value contains the internal revision of the document.

How do I find the object ID in MongoDB?

MongoDB provides a function with the name findById() which is used to retrieve the document matching the ‘id’ as specified by the user. In order to use findById in MongoDB, find() function is used. If no document is found matching the specified ‘id’, it returns null.

How does Mongoose fetch data?

How to Fetch Data From mongodb in Node js and Display in HTML (ejs)

1. Step 1 – Create Node Express js App.
2. Step 2 – Install express flash ejs body-parser mongoose dependencies.
3. Step 3 – Connect App to MongoDB.
4. Step 4 – Create Model.
5. Step 5 – Create Routes.
6. Step 6 – Create HTML Table and Display List.

What is a valid object ID?

ObjectId values are 12 bytes in length, consisting of: a 4-byte timestamp value, representing the ObjectId’s creation, measured in seconds since the Unix epoch. a 5-byte random value generated once per process. This random value is unique to the machine and process.

How does Mongoose populate work?

Mongoose Populate() Method. In MongoDB, Population is the process of replacing the specified path in the document of one collection with the actual document from the other collection.

What is Mongoose schema?

A Mongoose schema defines the structure of the document, default values, validators, etc., whereas a Mongoose model provides an interface to the database for creating, querying, updating, deleting records, etc.

What is __ V 0 in Mongoose?

The __v field is called the version key. It describes the internal revision of a document. This __v field is used to track the revisions of a document. By default, its value is zero.

What is object ID in mongoose?

What is a Mongoose query?

The Mongoose Query class provides a chaining interface for finding, updating, and deleting documents.