CS157C

Neo4j Backend Setup

Setup

1. Install dependencies: pip install neo4j pandas python-dotenv bcrypt

2. Create .env file using .env.example

3. Start Neo4j Desktop and run your database

4. Initialize constraints: python setup_constraints.py

5. Test connection: python test.py

Frontend Setup

Console-based Python front-end (using 'main.py') that covers all 11 use cases.

Prerequesites

• Python3.10+ - Download here

• Backend setup (see steps above)

Step 1 - Add 'main.py'

Place 'main.py' in the same directory as 'queries.py' and 'db.py':

CS157C/
├── main.py   
├── queries.py
├── db.py
├── setup_constraints.py
├── test.py
├── .env
└── .env.example

Step 2 - Run the Frontend

Make sure your Neo4j database is running, then:

python3 main.py

You will see the main menu:

══════════════════════════════════════════════════════
  SocialGraph  ·  CS157C Team Project
══════════════════════════════════════════════════════
  Graph-powered social network  |  Neo4j backend
 
══════════════════════════════════════════════════════
  SocialGraph  ·  Welcome
══════════════════════════════════════════════════════
  [1] Register
  [2] Login
  [0] Quit
  Select:

Available Query Functions

Import from queries.py to use these in the frontend:

from queries import create_user, login_user, get_profile, ...

Function	Parameters	Returns
create_user	name, username, email, password	(id, message)
login_user	username, password	(user_dict, message)
get_profile	user_id	user_dict
edit_profile	user_id, name=None, bio=None	message
follow_user	follower_id, followee_id	message
unfollow_user	follower_id, followee_id	message
get_following	user_id	list of {id, username}
get_followers	user_id	list of {id, username}
get_mutual_connections	user_id_a, user_id_b	list of {id, username}
get_recommendations	user_id	list of {id, username, commonConnections}
search_users	query	list of {id, username}
get_popular_users	limit=10	list of {id, username, followerCount}

Use Cases

#	Use Case	How to Access
UC-1	User Registration	Guest Menu → [1] Register
UC-2	User Login	Guest Menu → [2] Login
UC-3	View Profile	Main Menu → [1] View My Profile
UC-4	Edit Profile	Main Menu → [2] Edit Profile
UC-5	Follow a User	Main Menu → [3] Follow a User
UC-6	Unfollow a User	Main Menu → [4] Unfollow a User
UC-7	View Following/Followers	Main Menu → [5] View Following/Followers
UC-8	Mutual Connections	Main Menu → [6] Mutual Connections
UC-9	Friend Recommendations	Main Menu → [7] Friend Recommendations
UC-10	Search Users	Main Menu → [8] Search Users
UC-11	Explore Popular Users	Main Menu → [9] Popular Users

Troubleshooting

ModuleNotFoundError: No module named 'neo4j'
→ Re-run pip install neo4j python-dotenv bcrypt

Connection refused or ServiceUnavailable
→ Make sure Neo4j Desktop is running and the database is started.
→ Check that NEO4J_URI in .env matches the bolt port shown in Neo4j Desktop (default: 7687).

Authentication failed
→ Verify NEO4J_USERNAME and NEO4J_PASSWORD in .env match your Neo4j credentials.

Username already taken when registering
→ That username exists in the database. Try a different one.