Graduate Program KB

To create the entities and relationships using MongoDB with JavaScript, follow these steps:

1. Install the mongodb package:

npm install mongodb

2. Initialize the MongoDB database connection:

const MongoClient = require('mongodb').MongoClient;

const uri = 'mongodb://localhost:27017';
const dbName = 'blogDatabase';

async function getDb() {
  const client = new MongoClient(uri);
  await client.connect();
  return client.db(dbName);
}

3. Define a function to create a blog post:

async function createBlogPost(title, content, author, tags) {
  const db = await getDb();
  const postsCollection = db.collection('posts');

  const post = {
    title,
    content,
    author,
    tags,
    createdAt: new Date(),
  };

  await postsCollection.insertOne(post);
  console.log(`Created post: ${title}`);
}

4. Load dummy data:

async function loadDummyData() {
  await createBlogPost('A sample blog post', 'This is the content of the blog post.', 'Alice', ['technology', 'mongodb']);
  await createBlogPost('Another blog post', 'This is another content of the blog post.', 'Bob', ['technology', 'javascript']);
}

loadDummyData();

5. Define a function to query blog posts with a specific tag:

async function findBlogPostsByTag(tag) {
  const db = await getDb();
  const postsCollection = db.collection('posts');

  const posts = await postsCollection.find({ tags: tag }).toArray();

  console.log(`Posts with tag "${tag}":`);
  posts.forEach((post) => {
    console.log(post.title);
  });
}

6. Query blog posts with a specific tag:

async function main() {
  await loadDummyData();
  await findBlogPostsByTag('technology');
}

main();

This example demonstrates how to create entities in MongoDB using the mongodb package and JavaScript. The database is initialized and loaded with dummy data, and you can query the blog posts with a specific tag.

To expand on the examples, we will store and query comments related to blog posts.

1. Define a function to create a comment for a blog post:

async function createComment(postId, author, content) {
  const db = await getDb();
  const commentsCollection = db.collection('comments');

  const comment = {
    postId,
    author,
    content,
    createdAt: new Date(),
  };

  await commentsCollection.insertOne(comment);
  console.log(`Created comment by ${author} on post ${postId}`);
}

2. Load additional dummy data:

async function loadAdditionalDummyData() {
  const db = await getDb();
  const postsCollection = db.collection('posts');
  const post1 = await postsCollection.findOne({ title: 'A sample blog post' });
  const post2 = await postsCollection.findOne({ title: 'Another blog post' });

  await createComment(post1._id, 'Bob', 'This is a comment on the first post');
  await createComment(post2._id, 'Alice', 'This is a comment on the second post');
}

3. Define a function to query comments for a blog post:

async function getCommentsForPost(postId) {
  const db = await getDb();
  const commentsCollection = db.collection('comments');
  const postComments = await commentsCollection.find({ postId }).toArray();

  console.log(`Comments for post ${postId}:`);
  postComments.forEach((comment) => {
    console.log(`${comment.author}: ${comment.content}`);
  });
}

4. Query comments for a blog post:

async function main() {
  await loadDummyData();
  await loadAdditionalDummyData();
  const db = await getDb();
  const postsCollection = db.collection('posts');
  const post1 = await posts
  Collection.findOne({ title: 'A sample blog post' });
  const post2 = await postsCollection.findOne({ title: 'Another blog post' });

  await findBlogPostsByTag('technology');
  await getCommentsForPost(post1._id);
  await getCommentsForPost(post2._id);
}

main();

These expanded examples demonstrate how to create and query additional relationships and entities for MongoDB using JavaScript. We added the functionality to create and query comments related to blog posts.

Remember to call the loadAdditionalDummyData() function in the main() function to load the new data.

To further expand on the examples, we will store and query the categories associated with blog posts.

1. Define a function to add a category to a blog post:

async function addCategoryToPost(postId, category) {
  const db = await getDb();
  const postsCollection = db.collection('posts');

  await postsCollection.updateOne(
    { _id: postId },
    { $addToSet: { categories: category } }
  );
  console.log(`Added category "${category}" to post ${postId}`);
}

2. Load additional dummy data:

async function loadMoreDummyData() {
  const db = await getDb();
  const postsCollection = db.collection('posts');
  const post1 = await postsCollection.findOne({ title: 'A sample blog post' });
  const post2 = await postsCollection.findOne({ title: 'Another blog post' });

  await addCategoryToPost(post1._id, 'Technology');
  await addCategoryToPost(post2._id, 'Programming');
}

3. Define a function to query blog posts with a specific category:

async function findBlogPostsByCategory(category) {
  const db = await getDb();
  const postsCollection = db.collection('posts');
  const posts = await postsCollection.find({ categories: category }).toArray();

  console.log(`Posts in category "${category}":`);
  posts.forEach((post) => {
    console.log(post.title);
  });
}

4. Query blog posts with a specific category:

async function main() {
  await loadDummyData();
  await loadAdditionalDummyData();
  await loadMoreDummyData();
  await findBlogPostsByTag('technology');
  await findBlogPostsByCategory('Technology');
}

main();

These further expanded examples demonstrate how to create and query additional relationships and entities. We added the functionality to create and query categories associated with blog posts.

Remember to call the loadMoreDummyData() function in the main() function to load the new data for the expanded examples.

These expanded examples highlight the power and flexibility of NoSQL databases in modeling various data structures and relationships, providing various querying options for different use cases.