Q1. What is a Mongoose schema?
A schema defines the structure of documents within a collection, including field names, data types, default values, validations, and options. Example:
const userSchema = new mongoose.Schema({
name: { type: String, required: true },
age: { type: Number, min: 0 },
email: { type: String, unique: true },
createdAt: { type: Date, default: Date.now }
});
Q2. What are schema types in Mongoose?
Common schema types: String, Number, Date, Boolean, Buffer, ObjectId, Array, Map, Mixed, Decimal128. You can also nest schemas:
address: {
street: String,
city: String,
zip: Number
}
Q3. How do you define indexes in Mongoose schemas?
Indexes can be defined in the schema:
userSchema.index({ email: 1 }, { unique: true });
userSchema.index({ age: -1, name: 1 });
new mongoose.Schema({...}, { autoIndex: true });
Q4. What is the difference between schema and model?
A schema defines the structure, validation, and middleware. A model is a compiled version of the schema that provides an interface to interact with a specific collection. You create a model from a schema:
const User = mongoose.model('User', userSchema);
Q5. How do you use virtual properties in Mongoose?
Virtuals are document properties that are not stored in MongoDB. They are computed from other fields:
userSchema.virtual('fullName').get(function() {
return this.firstName + ' ' + this.lastName;
});