Write Python code in n8n Code nodes. Use when writing Python in n8n, using _input/_json/_node syntax, working with standard library, or need to understand Python limitations in n8n Code nodes. Use this skill when the user specifically requests Python for an n8n Code node. Note — JavaScript is recommended for 95% of use cases — only use Python when the user explicitly prefers it or the task requires Python-specific standard library capabilities (regex, hashlib, statistics).
Expert guidance for writing Python code in n8n Code nodes.
Recommendation: Use JavaScript for 95% of use cases. Only use Python when:
Why JavaScript is preferred:
# Basic template for Python Code nodes
items = _input.all()
# Process data
processed = []
for item in items:
processed.append({
"json": {
**item["json"],
"processed": True,
"timestamp": datetime.now().isoformat()
}
})
return processed
_input.all(), _input.first(), or _input.item[{"json": {...}}] format_json["body"] (not _json directly)Same as JavaScript - choose based on your use case:
Use this mode for: 95% of use cases
_input.all() or _items array (Native mode)# Example: Calculate total from all items
all_items = _input.all()
total = sum(item["json"].get("amount", 0) for item in all_items)
return [{
"json": {
"total": total,
"count": len(all_items),
"average": total / len(all_items) if all_items else 0
}
}]
Use this mode for: Specialized cases only
_input.item or _item (Native mode)# Example: Add processing timestamp to each item
item = _input.item
return [{
"json": {
**item["json"],
"processed": True,
"processed_at": datetime.now().isoformat()
}
}]
n8n offers two Python execution modes:
_input, _json, _node helper syntax_now, _today, _jmespath()from datetime import datetime# Python (Beta) example
items = _input.all()
now = _now # Built-in datetime object
return [{
"json": {
"count": len(items),
"timestamp": now.isoformat()
}
}]
_items, _item variables only_input, _now, etc.# Python (Native) example
processed = []
for item in _items:
processed.append({
"json": {
"id": item["json"].get("id"),
"processed": True
}
})
return processed
Recommendation: Use Python (Beta) for better n8n integration.
Use when: Processing arrays, batch operations, aggregations
# Get all items from previous node
all_items = _input.all()
# Filter, transform as needed
valid = [item for item in all_items if item["json"].get("status") == "active"]
processed = []
for item in valid:
processed.append({
"json": {
"id": item["json"]["id"],
"name": item["json"]["name"]
}
})
return processed
Use when: Working with single objects, API responses
# Get first item only
first_item = _input.first()
data = first_item["json"]
return [{
"json": {
"result": process_data(data),
"processed_at": datetime.now().isoformat()
}
}]
Use when: In "Run Once for Each Item" mode
# Current item in loop (Each Item mode only)
current_item = _input.item
return [{
"json": {
**current_item["json"],
"item_processed": True
}
}]
Use when: Need data from specific nodes in workflow
# Get output from specific node
webhook_data = _node["Webhook"]["json"]
http_data = _node["HTTP Request"]["json"]
return [{
"json": {
"combined": {
"webhook": webhook_data,
"api": http_data
}
}
}]
See: DATA_ACCESS.md for comprehensive guide
MOST COMMON MISTAKE: Webhook data is nested under ["body"]
# ❌ WRONG - Will raise KeyError
name = _json["name"]
email = _json["email"]
# ✅ CORRECT - Webhook data is under ["body"]
name = _json["body"]["name"]
email = _json["body"]["email"]
# ✅ SAFER - Use .get() for safe access
webhook_data = _json.get("body", {})
name = webhook_data.get("name")
Why: Webhook node wraps all request data under body property. This includes POST data, query parameters, and JSON payloads.
See: DATA_ACCESS.md for full webhook structure details
CRITICAL RULE: Always return list of dictionaries with "json" key
# ✅ Single result
return [{
"json": {
"field1": value1,
"field2": value2
}
}]
# ✅ Multiple results
return [
{"json": {"id": 1, "data": "first"}},
{"json": {"id": 2, "data": "second"}}
]
# ✅ List comprehension
transformed = [
{"json": {"id": item["json"]["id"], "processed": True}}
for item in _input.all()
if item["json"].get("valid")
]
return transformed
# ✅ Empty result (when no data to return)
return []
# ✅ Conditional return
if should_process:
return [{"json": processed_data}]