Data Types
Basic Data Types
String
// Basic string
{ name: "John Doe" }
// String with special characters
{ description: "Product with 50% discount!" }
// Empty string
{ title: "" }
// Multiline string
{ bio: "This is a\nmultiline\nstring" }
// String with quotes
{ message: "He said \"Hello World\"" }
// String with unicode
{ text: "Café résumé naïve" }Number
// Integer
{ age: 25 }
// Double/Float
{ price: 99.99 }
// Negative number
{ temperature: -5.5 }
// Scientific notation
{ distance: 1.5e6 } // 1,500,000
// Zero
{ count: 0 }
// Large numbers
{ population: 7800000000 }Boolean
// True value
{ isActive: true }
// False value
{ isDeleted: false }
// Boolean in conditions
{ verified: true }Null
// Null value
{ middleName: null }
// Missing field (different from null)
{ name: "John" } // middleName field doesn't exist
// Explicit null assignment
{ status: null }Date
// Current date
{ createdAt: new Date() }
// Specific date
{ birthDate: new Date("1990-05-15") }
// Date with time
{ orderDate: new Date("2023-12-25T10:30:00Z") }
// Date from timestamp
{ timestamp: new Date(1640995200000) }
// Date arithmetic
{ futureDate: new Date(Date.now() + 86400000) } // TomorrowObjectId
// Auto-generated ObjectId
{ _id: ObjectId() }
// Specific ObjectId
{ userId: ObjectId("507f1f77bcf86cd799439011") }
// ObjectId from string
{ productId: ObjectId("507f1f77bcf86cd799439011") }
// ObjectId in queries
{ _id: ObjectId("507f1f77bcf86cd799439011") }Complex Data Types
Array
// Simple array
{ tags: ["javascript", "mongodb", "nodejs"] }
// Array of numbers
{ scores: [85, 92, 78, 96] }
// Array of objects
{ addresses: [
{ type: "home", street: "123 Main St", city: "New York" },
{ type: "work", street: "456 Business Ave", city: "Los Angeles" }
] }
// Mixed array
{ data: ["string", 42, true, { key: "value" }] }
// Empty array
{ items: [] }
// Nested arrays
{ matrix: [[1, 2, 3], [4, 5, 6], [7, 8, 9]] }Object/Document
// Simple object
{ profile: { firstName: "John", lastName: "Doe" } }
// Nested object
{ user: {
profile: {
firstName: "John",
lastName: "Doe",
contact: {
email: "john@example.com",
phone: "+1-555-1234"
}
}
}}
// Object with arrays
{ product: {
name: "Laptop",
specs: {
cpu: "Intel i7",
ram: "16GB",
storage: ["256GB SSD", "1TB HDD"]
}
}}
// Empty object
{ metadata: {} }Binary Data
// Binary data
{ image: BinData(0, "SGVsbG8gV29ybGQ=") }
// Binary with subtype
{ file: BinData(1, "base64encodeddata") }
// UUID as binary
{ uuid: BinData(3, "base64encodeduuid") }Special Data Types
Regular Expression
// Regex pattern
{ pattern: /john/i }
// Regex with options
{ emailPattern: /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/ }
// Regex object
{ regex: { $regex: "john", $options: "i" } }JavaScript Code
// JavaScript function
{ function: function() { return "Hello World"; } }
// JavaScript with scope
{ code: Code("function() { return this.name; }", { name: "John" }) }Timestamp
// Timestamp
{ timestamp: Timestamp(1640995200, 1) }
// Current timestamp
{ currentTime: Timestamp() }Decimal128
// High precision decimal
{ price: NumberDecimal("99.99") }
// Financial calculations
{ amount: NumberDecimal("1234.5678") }MinKey/MaxKey
// MinKey (smallest possible value)
{ minValue: MinKey }
// MaxKey (largest possible value)
{ maxValue: MaxKey }Date and Time Types
ISODate
// ISO date string
{ isoDate: ISODate("2023-12-25T10:30:00Z") }
// ISO date with timezone
{ localDate: ISODate("2023-12-25T10:30:00-05:00") }
// ISO date from string
{ eventDate: ISODate("2023-12-25") }Date Operations
// Date arithmetic
{ tomorrow: new Date(Date.now() + 24 * 60 * 60 * 1000) }
// Date comparison
{ isExpired: { $lt: ["$expiryDate", new Date()] } }
// Date formatting
{ formattedDate: { $dateToString: { format: "%Y-%m-%d", date: "$createdAt" } } }Array and Object Operations
Array Elements
// Access array element
{ firstTag: "$tags.0" }
// Array length
{ tagCount: { $size: "$tags" } }
// Array slice
{ topScores: { $slice: ["$scores", 0, 3] } }
// Array element matching
{ highScores: { $filter: { input: "$scores", cond: { $gte: ["$$this", 80] } } } }Object Fields
// Access nested field
{ firstName: "$profile.firstName" }
// Nested object access
{ email: "$profile.contact.email" }
// Object field existence
{ hasProfile: { $exists: "$profile" } }Type Checking and Validation
Type Validation
// Check field type
{ isString: { $type: "string" } }
// Type checking in queries
{ age: { $type: "number" } }
// Multiple type checking
{ field: { $type: ["string", "number"] } }Type Conversion
// String to number
{ numericAge: { $toInt: "$ageString" } }
// Number to string
{ ageString: { $toString: "$age" } }
// String to date
{ parsedDate: { $dateFromString: { dateString: "$dateString" } } }
// Date to string
{ dateString: { $dateToString: { date: "$date" } } }Data Type Examples in Documents
User Document
{
_id: ObjectId("507f1f77bcf86cd799439011"),
username: "johndoe",
email: "john@example.com",
age: 30,
isActive: true,
profile: {
firstName: "John",
lastName: "Doe",
birthDate: new Date("1993-05-15"),
addresses: [
{
type: "home",
street: "123 Main St",
city: "New York",
zipCode: "10001"
}
]
},
tags: ["developer", "javascript", "mongodb"],
scores: [85, 92, 78],
metadata: {
lastLogin: new Date(),
loginCount: 42,
preferences: {
theme: "dark",
notifications: true
}
}
}Product Document
{
_id: ObjectId("507f1f77bcf86cd799439012"),
name: "Laptop",
price: NumberDecimal("999.99"),
category: "electronics",
inStock: true,
specs: {
cpu: "Intel i7",
ram: "16GB",
storage: ["256GB SSD", "1TB HDD"],
dimensions: {
width: 15.6,
height: 0.8,
depth: 10.2
}
},
tags: ["laptop", "computer", "electronics"],
ratings: [4.5, 4.2, 4.8, 4.6],
createdAt: new Date(),
updatedAt: new Date()
}Order Document
{
_id: ObjectId("507f1f77bcf86cd799439013"),
orderNumber: "ORD-2023-001",
customerId: ObjectId("507f1f77bcf86cd799439011"),
items: [
{
productId: ObjectId("507f1f77bcf86cd799439012"),
name: "Laptop",
price: NumberDecimal("999.99"),
quantity: 1
}
],
total: NumberDecimal("999.99"),
status: "pending",
orderDate: new Date(),
shippingAddress: {
street: "123 Main St",
city: "New York",
state: "NY",
zipCode: "10001",
country: "USA"
},
payment: {
method: "credit_card",
cardLast4: "1234",
amount: NumberDecimal("999.99")
}
}Type-Specific Queries
String Queries
// Case insensitive search
{ name: { $regex: /john/i } }
// String length
{ description: { $exists: true, $ne: "" } }
// String contains
{ tags: { $in: ["javascript"] } }Number Queries
// Range queries
{ age: { $gte: 18, $lte: 65 } }
// Exact match
{ price: 99.99 }
// Multiple values
{ score: { $in: [85, 90, 95] } }Date Queries
// Date range
{ createdAt: { $gte: new Date("2023-01-01"), $lt: new Date("2023-12-31") } }
// Recent documents
{ updatedAt: { $gte: new Date(Date.now() - 24 * 60 * 60 * 1000) } }
// Date comparison
{ expiryDate: { $lt: new Date() } }Array Queries
// Array contains element
{ tags: "javascript" }
// Array contains all elements
{ tags: { $all: ["javascript", "mongodb"] } }
// Array size
{ tags: { $size: 3 } }
// Array element at position
{ "scores.0": { $gte: 80 } }Object Queries
// Nested field query
{ "profile.firstName": "John" }
// Object field exists
{ "profile.contact": { $exists: true } }
// Nested object match
{ "profile.contact.email": "john@example.com" }Data Type Best Practices
Performance Considerations
// Use appropriate types for indexing
{ userId: ObjectId("507f1f77bcf86cd799439011") } // Better than string
// Use integers for counts
{ viewCount: 42 } // Better than "42"
// Use dates for timestamps
{ createdAt: new Date() } // Better than string timestampsValidation
// Validate data types
{ age: { $type: "number", $gte: 0, $lte: 150 } }
// Validate email format
{ email: { $regex: /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/ } }
// Validate required fields
{ name: { $exists: true, $ne: "" } }Consistency
// Consistent naming
{ firstName: "John" } // camelCase
{ last_name: "Doe" } // snake_case (choose one style)
// Consistent data types
{ price: 99.99 } // Always use NumberDecimal for money
{ quantity: 5 } // Always use integer for countsLast updated