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Your First Graph

In this tutorial, you'll build a simple social network graph to learn the fundamentals of Grafeo.

What We'll Build

A social network with:

  • People with names, ages, and locations
  • Friendships between people
  • Posts created by people
  • Likes on posts

Step 1: Create the Database

import grafeo

# Create a persistent database
db = grafeo.Database(path="social_network.db")

use grafeo::Database;

let db = Database::open("social_network.db")?;

Step 2: Add People

with db.session() as session:
    session.execute("""
        INSERT (:Person {
            name: 'Alice',
            age: 30,
            location: 'New York'
        })
        INSERT (:Person {
            name: 'Bob',
            age: 25,
            location: 'San Francisco'
        })
        INSERT (:Person {
            name: 'Carol',
            age: 35,
            location: 'New York'
        })
        INSERT (:Person {
            name: 'Dave',
            age: 28,
            location: 'Los Angeles'
        })
    """)

let session = db.session()?;

session.execute(r#"
    INSERT (:Person {
        name: 'Alice',
        age: 30,
        location: 'New York'
    })
    INSERT (:Person {
        name: 'Bob',
        age: 25,
        location: 'San Francisco'
    })
    INSERT (:Person {
        name: 'Carol',
        age: 35,
        location: 'New York'
    })
    INSERT (:Person {
        name: 'Dave',
        age: 28,
        location: 'Los Angeles'
    })
"#)?;

Step 3: Create Friendships

with db.session() as session:
    # Alice knows Bob and Carol
    session.execute("""
        MATCH (a:Person {name: 'Alice'}), (b:Person {name: 'Bob'})
        INSERT (a)-[:FRIENDS_WITH {since: 2020}]->(b)
    """)

    session.execute("""
        MATCH (a:Person {name: 'Alice'}), (c:Person {name: 'Carol'})
        INSERT (a)-[:FRIENDS_WITH {since: 2019}]->(c)
    """)

    # Bob knows Dave
    session.execute("""
        MATCH (b:Person {name: 'Bob'}), (d:Person {name: 'Dave'})
        INSERT (b)-[:FRIENDS_WITH {since: 2021}]->(d)
    """)

    # Carol knows Dave
    session.execute("""
        MATCH (c:Person {name: 'Carol'}), (d:Person {name: 'Dave'})
        INSERT (c)-[:FRIENDS_WITH {since: 2022}]->(d)
    """)

let session = db.session()?;

session.execute(r#"
    MATCH (a:Person {name: 'Alice'}), (b:Person {name: 'Bob'})
    INSERT (a)-[:FRIENDS_WITH {since: 2020}]->(b)
"#)?;

session.execute(r#"
    MATCH (a:Person {name: 'Alice'}), (c:Person {name: 'Carol'})
    INSERT (a)-[:FRIENDS_WITH {since: 2019}]->(c)
"#)?;

session.execute(r#"
    MATCH (b:Person {name: 'Bob'}), (d:Person {name: 'Dave'})
    INSERT (b)-[:FRIENDS_WITH {since: 2021}]->(d)
"#)?;

session.execute(r#"
    MATCH (c:Person {name: 'Carol'}), (d:Person {name: 'Dave'})
    INSERT (c)-[:FRIENDS_WITH {since: 2022}]->(d)
"#)?;

Step 4: Add Posts

with db.session() as session:
    session.execute("""
        INSERT (:Post {
            id: 1,
            content: 'Hello, world!',
            created_at: '2024-01-15'
        })
        INSERT (:Post {
            id: 2,
            content: 'Learning Grafeo is fun!',
            created_at: '2024-01-16'
        })
        INSERT (:Post {
            id: 3,
            content: 'Graph databases are amazing.',
            created_at: '2024-01-17'
        })
    """)

    # Connect posts to authors
    session.execute("""
        MATCH (a:Person {name: 'Alice'}), (p:Post {id: 1})
        INSERT (a)-[:POSTED]->(p)
    """)

    session.execute("""
        MATCH (b:Person {name: 'Bob'}), (p:Post {id: 2})
        INSERT (b)-[:POSTED]->(p)
    """)

    session.execute("""
        MATCH (c:Person {name: 'Carol'}), (p:Post {id: 3})
        INSERT (c)-[:POSTED]->(p)
    """)

Step 5: Add Likes

with db.session() as session:
    # Bob likes Alice's post
    session.execute("""
        MATCH (b:Person {name: 'Bob'}), (p:Post {id: 1})
        INSERT (b)-[:LIKES]->(p)
    """)

    # Carol likes Alice's and Bob's posts
    session.execute("""
        MATCH (c:Person {name: 'Carol'}), (p:Post)
        WHERE p.id IN [1, 2]
        INSERT (c)-[:LIKES]->(p)
    """)

    # Dave likes all posts
    session.execute("""
        MATCH (d:Person {name: 'Dave'}), (p:Post)
        INSERT (d)-[:LIKES]->(p)
    """)

Step 6: Query the Graph

Now let's explore the social network:

Find All Friends of Alice

with db.session() as session:
    result = session.execute("""
        MATCH (a:Person {name: 'Alice'})-[:FRIENDS_WITH]->(friend)
        RETURN friend.name, friend.location
    """)

    print("Alice's friends:")
    for row in result:
        print(f"  - {row['friend.name']} from {row['friend.location']}")

Find Friends of Friends

with db.session() as session:
    result = session.execute("""
        MATCH (a:Person {name: 'Alice'})-[:FRIENDS_WITH]->()-[:FRIENDS_WITH]->(fof)
        WHERE fof <> a
        RETURN DISTINCT fof.name
    """)

    print("Friends of Alice's friends:")
    for row in result:
        print(f"  - {row['fof.name']}")

Find People in the Same Location

with db.session() as session:
    result = session.execute("""
        MATCH (p:Person)
        RETURN p.location AS location, collect(p.name) AS people
    """)

    print("People by location:")
    for row in result:
        print(f"  {row['location']}: {row['people']}")

Find Most Liked Posts

with db.session() as session:
    result = session.execute("""
        MATCH (p:Post)<-[:LIKES]-(person)
        MATCH (author)-[:POSTED]->(p)
        RETURN p.content AS post, author.name AS author, count(person) AS likes
        ORDER BY likes DESC
    """)

    print("Posts by popularity:")
    for row in result:
        print(f"  '{row['post']}' by {row['author']} - {row['likes']} likes")

Find Mutual Friends

with db.session() as session:
    result = session.execute("""
        MATCH (a:Person {name: 'Alice'})-[:FRIENDS_WITH]->(mutual)<-[:FRIENDS_WITH]-(b:Person {name: 'Bob'})
        RETURN mutual.name
    """)

    print("Mutual friends of Alice and Bob:")
    for row in result:
        print(f"  - {row['mutual.name']}")

The Complete Graph

Here's a visualization of what we've built:

graph LR
    Alice((Alice)) -->|FRIENDS_WITH| Bob((Bob))
    Alice -->|FRIENDS_WITH| Carol((Carol))
    Bob -->|FRIENDS_WITH| Dave((Dave))
    Carol -->|FRIENDS_WITH| Dave

    Alice -->|POSTED| P1[Post 1]
    Bob -->|POSTED| P2[Post 2]
    Carol -->|POSTED| P3[Post 3]

    Bob -->|LIKES| P1
    Carol -->|LIKES| P1
    Carol -->|LIKES| P2
    Dave -->|LIKES| P1
    Dave -->|LIKES| P2
    Dave -->|LIKES| P3

Next Steps

Congratulations! You've built your first graph application. Continue learning: