7a. Find all listings with listing_url, name, address, host_picture_url in the listings And Reviews collection that have a host with a picture url.
use vacationRentalsdb.listingsAndReviews.insertMany([
{
listing_url: "http://www.example.com/listing/123456",
name: "Beautiful Apartment",
address: {
street: "123 Main Street",
suburb: "Central",
city: "Metropolis",
country: "Wonderland"
},
host: {
name: "Alice",
picture_url: "http://www.example.com/images/host/host123.jpg"
}
},
{
listing_url: "http://www.example.com/listing/654321",
name: "Cozy Cottage",
address: {
street: "456 Another St",
suburb: "North",
city: "Smallville",
country: "Wonderland"
},
host: {
name: "Bob",
picture_url: ""
}
},
{
listing_url: "http://www.example.com/listing/789012",
name: "Modern Condo",
address: {
street: "789 Side Road",
suburb: "East",
city: "Gotham",
country: "Wonderland"
},
host: {
name: "Charlie",
picture_url: "http://www.example.com/images/host/host789.jpg"
}
}
])Query to Find Listings with Host Picture URLs:
Note: Now that the collection is set up, you can run the query to find all listings with listing_url, name, address, and host_picture_url where the host has a picture URL.
db.listingsAndReviews.find(
{
"host.picture_url": { $exists: true, $ne: "" }
},
{
listing_url: 1,
name: 1,
address: 1,
"host.picture_url": 1
}
).pretty()
OUTPUT:
[
{
_id: ObjectId('666c40ce85a7615d27cdcdfb'),
listing_url: 'http://www.example.com/listing/123456',
name: 'Beautiful Apartment',
address: {
street: '123 Main Street',
suburb: 'Central',
city: 'Metropolis',
country: 'Wonderland'
},
host: { picture_url: 'http://www.example.com/images/host/host123.jpg' }
},
{
_id: ObjectId('666c40ce85a7615d27cdcdfd'),
listing_url: 'http://www.example.com/listing/789012',
name: 'Modern Condo',
address: {
street: '789 Side Road',
suburb: 'East',
city: 'Gotham',
country: 'Wonderland'
},
host: { picture_url: 'http://www.example.com/images/host/host789.jpg' }
}
]7b. Using E-commerce collection write a query to display reviews summary.
use ecommercedb.products.insertMany([
{
product_id: 1,
name: "Laptop",
category: "Electronics",
price: 1200,
reviews: [
{ user: "Alice", rating: 5, comment: "Excellent!" },
{ user: "Bob", rating: 4, comment: "Very good" },
{ user: "Charlie", rating: 3, comment: "Average" }
]
},
{
product_id: 2,
name: "Smartphone",
category: "Electronics",
price: 800,
reviews: [
{ user: "Dave", rating: 4, comment: "Good phone" },
{ user: "Eve", rating: 2, comment: "Not satisfied" },
{ user: "Frank", rating: 5, comment: "Amazing!" }
]
},
{
product_id: 3,
name: "Headphones",
category: "Accessories",
price: 150,
reviews: [
{ user: "Grace", rating: 5, comment: "Great sound" },
{ user: "Heidi", rating: 3, comment: "Okay" }
]
}
])Query to Find E-commerce collection:
Note: To display a summary of reviews in an e-commerce collection, we can assume the ecommerce database contains a products collection with documents structured to include reviews. Each product document could have a reviews array with review details such as rating, comment, and user.
db.products.aggregate([
{
$unwind: "$reviews"
},
{
$group: {
_id: "$name",
totalReviews: { $sum: 1 },
averageRating: { $avg: "$reviews.rating" },
comments: { $push: "$reviews.comment" }
}
},
{
$project: {
_id: 0,
product: "$_id",
totalReviews: 1,
averageRating: 1,
comments: 1
}
}
]).pretty()
OUTPUT:
[
{
totalReviews: 3,
averageRating: 4,
comments: [ 'Excellent!', 'Very good', 'Average' ],
product: 'Laptop'
},
{
totalReviews: 3,
averageRating: 3.6666666666666665,
comments: [ 'Good phone', 'Not satisfied', 'Amazing!' ],
product: 'Smartphone'
},
{
totalReviews: 2,
averageRating: 4,
comments: [ 'Great sound', 'Okay' ],
product: 'Headphones'
}
]