👐 INSERT → insertOne() & DELETE → deleteOne()

MongoDB provides two methods for inserting documents into a collection:

• .insertOne(): Inserts a single document
• .insertMany(): Inserts multiple documents at once

And just like insert, MongoDB provides:

• .deleteOne(): Deletes the first matching document.
• .deleteMany(): Deletes all matching documents.

Example: Insert a new review

db.reviews.insertOne({
  text: "Best book I have ever read.",
  rating: 5,
  name: "Jack",
  bookId: "0786222727",
});

Equivalent SQL query

INSERT INTO reviews (text, rating, name, bookId)
VALUES ('Best book I have ever read.', 5, 'Jack', '0786222727');

Example: Insert multiple reviews

db.reviews.insertMany([
  {
    text: "Amazing plot.",
    rating: 5,
    name: "John",
    bookId: "0786222727",
  },
  {
    text: "Over-hyped, tbh I feel it's very boring!",
    rating: 2,
    name: "Nick",
    bookId: "0786222727",
  },
]);

Example: Delete one review

db.reviews.deleteOne({
  bookId: "0786222727",
});

Equivalent SQL query

DELETE FROM reviews WHERE bookId = '0786222727';

Challenge

👐 1. Insert 4 more reviews for bookId "0786222727".

Answer

JavaScript

const reviews = db.collection("reviews");
await reviews.insertMany([
  {
    text: "Thrilling end.",
    rating: 4,
    name: "Mark",
    bookId: "0786222727",
  },
  {
    text: "Must read!",
    rating: 5,
    name: "Raj",
    bookId: "0786222727",
  },
  {
    text: "Very expensive",
    rating: 3,
    name: "Yun",
    bookId: "0786222727",
  },
  {
    text: "Extremely satisfied with the storyline!",
    rating: 5,
    name: "Lisa",
    bookId: "0786222727",
  }
]);

mongosh

db.reviews.insertMany([
  {
    text: "Thrilling end.",
    rating: 4,
    name: "Mark",
    bookId: "0786222727",
  },
  {
    text: "Must read!",
    rating: 5,
    name: "Raj",
    bookId: "0786222727",
  },
  {
    text: "Very expensive",
    rating: 3,
    name: "Yun",
    bookId: "0786222727",
  },
  {
    text: "Extremely satisfied with the storyline!",
    rating: 5,
    name: "Lisa",
    bookId: "0786222727",
  }
]);

C#

var newReviews = new[]
{
    new Review { Text = "Thrilling end.", Rating = 4, Name = "Mark", BookId = "0786222727" },
    new Review { Text = "Must read!", Rating = 5, Name = "Raj",  BookId = "0786222727" },
    new Review { Text = "Very expensive", Rating = 3, Name = "Yun",  BookId = "0786222727" },
    new Review { Text = "Extremely satisfied with the storyline!", Rating = 5, Name = "Lisa", BookId = "0786222727" }
};

reviewsCollection.InsertMany(newReviews);

Python

reviews = db["reviews"]
reviews.insert_many([
    {
        "text": "Thrilling end.",
        "rating": 4,
        "name": "Mark",
        "bookId": "0786222727",
    },
    {
        "text": "Must read!",
        "rating": 5,
        "name": "Raj",
        "bookId": "0786222727",
    },
    {
        "text": "Very expensive",
        "rating": 3,
        "name": "Yun",
        "bookId": "0786222727",
    },
    {
        "text": "Extremely satisfied with the storyline!",
        "rating": 5,
        "name": "Lisa",
        "bookId": "0786222727",
    }
])

Java

var reviews = library.getCollection("reviews");

reviews.insertMany(List.of(
      new Document("text", "Thrilling end.")
              .append("rating", 4)
              .append("name", "Mark")
              .append("bookId", "0786222727"),

      new Document("text", "Very expensive")
              .append("rating", 3)
              .append("name", "Yun")
              .append("bookId", "0786222727"),

      new Document("text", "Must read!.")
              .append("rating", 6)
              .append("name", "Raj")
              .append("bookId", "0786222727"),

      new Document("text", "Extremely satisfied with the storyline!")
              .append("rating", 5)
              .append("name", "Lisa")
              .append("bookId", "0786222727")));

👐 2. Delete all the reviews for bookId "0786222727" through a single command.

Answer

JavaScript

const reviews = db.collection("reviews");
await reviews.deleteMany({"bookId": "0786222727"})

mongosh

db.reviews.deleteMany({"bookId": "0786222727"})

C#

IMongoCollection<Review> reviewsCollection = db.GetCollection<Review>("reviews");

var deletionResult = reviewsCollection.DeleteMany(r => r.BookId == "0786222727");

Console.WriteLine($"{deletionResult.DeletedCount} review(s) deleted.");

Python

reviews = db["reviews"]
reviews.delete_many({"bookId": "0786222727"})

Java

import static com.mongodb.client.model.Filters.eq;
import org.bson.conversions.Bson;

MongoCollection<Document> reviews = library.getCollection("reviews");

Bson filter = eq("bookId", "0786222727");

DeleteResult result = reviews.deleteMany(filter);
System.out.println(result.getDeletedCount() + " reviews deleted.");