Skip to main content

​
Iterate over collections with FOR loops  

Use FOR loops to perform operations on each element in a collection. The loop variable can reference the entire element or specific properties. 
FOR variable IN collection {
    // Access element properties: variable.property
    // Perform operations on each element
}
FOR loops process elements sequentially in the order they appear in the collection. This guarantees consistent execution order for dependent operations.
When using the SDKs or curling the endpoint, the query name must match what is defined in the queries.hx file exactly.

​
Example 1: Iterating over nodes to perform updates

QUERY UpdateUserStatus (user_updates: [{id: ID, status: String}]) =>
    FOR update IN user_updates {
        user <- N<User>(update.id)::UPDATE({
            status: update.status,
            last_updated: "2024-11-04"
        })
    }
    RETURN "Updated all users"

QUERY CreateUser (name: String, age: U8, email: String, status: String) =>
    user <- AddN<User>({
        name: name,
        age: age,
        email: email,
        status: status,
        last_updated: "2024-11-01"
    })
    RETURN user
Here’s how to run the query using the SDKs or curl 
from helix.client import Client

client = Client(local=True, port=6969)

# Create initial users
users = [
    {"name": "Alice", "age": 25, "email": "alice@example.com", "status": "active"},
    {"name": "Bob", "age": 30, "email": "bob@example.com", "status": "active"},
    {"name": "Charlie", "age": 28, "email": "charlie@example.com", "status": "active"},
]

user_ids = []
for user in users:
    result = client.query("CreateUser", user)
    user_ids.append(result["id"])

# Update their statuses using FOR loop
user_updates = [
    {"id": user_ids[0], "status": "inactive"},
    {"id": user_ids[1], "status": "pending"},
    {"id": user_ids[2], "status": "active"},
]

result = client.query("UpdateUserStatus", {"user_updates": user_updates})
print("Update result:", result)

​
Example 2: Processing query results

QUERY ArchiveInactiveUsers () =>
    inactive_users <- N<User>::WHERE(_::{status}::EQ("inactive"))
    FOR user IN inactive_users {
        user::UPDATE({ archived: true, archived_at: "2024-11-04" })
    }
    RETURN "Archived inactive users"

QUERY CreateUser (name: String, age: U8, email: String, status: String) =>
    user <- AddN<User>({
        name: name,
        age: age,
        email: email,
        status: status,
        archived: false,
        archived_at: ""
    })
    RETURN user
Here’s how to run the query using the SDKs or curl 
from helix.client import Client

client = Client(local=True, port=6969)

# Create users with different statuses
users = [
    {"name": "Alice", "age": 25, "email": "alice@example.com", "status": "inactive"},
    {"name": "Bob", "age": 30, "email": "bob@example.com", "status": "active"},
    {"name": "Charlie", "age": 28, "email": "charlie@example.com", "status": "inactive"},
    {"name": "Diana", "age": 22, "email": "diana@example.com", "status": "active"},
]

for user in users:
    client.query("CreateUser", user)

# Archive all inactive users
result = client.query("ArchiveInactiveUsers", {})
print("Archive result:", result)

​
Example 3: Batch operations on collections

QUERY LoadProducts (products: [{name: String, price: F64, category: String}]) =>
    FOR product IN products {
        new_product <- AddN<Product>({
            name: product.name,
            price: product.price,
            category: product.category,
            stock: 100
        })
    }
    RETURN "Products loaded successfully"
Here’s how to run the query using the SDKs or curl 
from helix.client import Client

client = Client(local=True, port=6969)

# Load multiple products in batch
products = [
    {"name": "Laptop", "price": 999.99, "category": "Electronics"},
    {"name": "Mouse", "price": 29.99, "category": "Electronics"},
    {"name": "Keyboard", "price": 79.99, "category": "Electronics"},
    {"name": "Monitor", "price": 299.99, "category": "Electronics"},
    {"name": "Desk Chair", "price": 199.99, "category": "Furniture"},
]

result = client.query("LoadProducts", {"products": products})
print("Load result:", result)

FOR Loop Destructuring

Extract multiple properties directly in loop variable binding

Nested FOR Loops

Use multiple levels of iteration for complex operations