This repository contains a simple Express API using Mongoose for two collections: User and Post.

1. Sign Up: Create a new user. (Email must be unique)
2. Sign In: Authenticate and log in.
3. Update User: Update user information.
4. Delete User: Delete a user.
5. Search Users by Name and Age: Search for users where the name starts with "X" and age is less than Y.
6. Search Users by Age Range: Search for users where the age is between X and Y.
7. Get All Users: Retrieve all users.
8. Get User Profile with Posts: Retrieve a user's profile along with their posts using populate.

1. Add Post: Add a new post. (Make sure the user already exists)
2. Delete Post: Delete a post (Post creator only).
3. Update Post: Update a post (Post owner only).
4. Get All Posts: Retrieve all posts.
5. Get All Posts with Owners Information: Retrieve all posts with their owners' information using populate.
6. Sort Posts Descending by Date: Retrieve all posts sorted in descending order by date.