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SKILL.md
npx skills add czlonkowski/n8n-skills --skill n8n-code-python
Write Python in n8n Code nodes (native Python, `language` pythonNative, n8n 2.x). Use when the user explicitly wants Python in a Code node, when migrating old Pyodide/"Python (Beta)" code that used _input/_json/_node/_now, or when a Python Code node fails with NameError, "Security violations detected", "Import of standard library module … is disallowed", "__build_class__ not found", "A 'json' property isn't a dictionary", or "Python runner unavailable". Covers the only two variables (_items/_item), dict-only access, imports blocked by default, the sandbox's denied builtins, accepted return shapes, and how errors interact with onError. JavaScript is the default for Code nodes — native Python has no n8n helpers and, by default, no imports. EXCEPTION — for Python in the AI-agent-callable Custom Code Tool (@n8n/n8n-nodes-langchain.toolCode), use the n8n-code-tool skill instead (input is _query, return must be a string).
npx skills add czlonkowski/n8n-skills --skill n8n-code-python
Since n8n 2.0 the Code node's Python runs as native Python in a task runner (language: "pythonNative"). The old Pyodide "Python (Beta)" is gone, and with it every n8n helper it had:
_input, _json, _node, _now, _today and _jmespath all raise NameError now. Code copied
from old templates, forum posts or older docs usually breaks on this.
Native Python gives you two variables and plain Python, and by default no imports: no
json, datetime or re. Everything n8n-specific ($('Node'), $jmespath, Luxon,
this.helpers.httpRequest, static data) exists only in JavaScript. Use Python only when the user
explicitly asks for it. Even then, first check whether an expression, Edit Fields, or a native
node (Crypto, Date & Time, HTML, XML) does the job. See n8n-code-javascript and the transform
gatekeeper in n8n-expression-syntax.
Node config: {"language": "pythonNative", "mode": "runOnceForAllItems" | "runOnceForEachItem", "pythonCode": "..."} on n8n-nodes-base.code typeVersion 2.
_items and _item| Mode | Variable | Shape |
|---|---|---|
| Run Once for All Items | _items | list of plain dicts {"json": {...}, "pairedItem": {...}} |
| Run Once for Each Item | _item | one plain dict {"json": {...}, "pairedItem": {...}} |
_items in each-item mode (or _item in
all-items mode) raises NameError.it["json"]["name"] or it["json"].get("name"). it.json.name raises
AttributeError: 'dict' object has no attribute 'json'._node / $('Node') equivalent. If you need data from another
branch, bring it in with Merge first, or read it in JavaScript.["body"]: _items[0]["json"].get("body", {}).get("email")._items / _item keeps it. When you build new dicts and downstream
uses $('Node').item, add "pairedItem": {"item": i} to each returned item. That isn't
verified on native Python yet, so test-run before relying on it..get(key, default). row["missing"] raises KeyError.Migration table for legacy code:
| Legacy (Pyodide) | Native |
|---|---|
_input.all() | _items |
_input.first()["json"] | _items[0]["json"] (guard if _items) |
_input.item / _json | _item / _item["json"] |
_node["X"] | not available: Merge upstream, or use JS |
_now, _today | not available: pass {{ $now.toISO() }} in via Edit Fields, or use JS |
_jmespath(data, q) | not available: $jmespath in an expression, or a comprehension |
item.json.field | item["json"]["field"] |
Every import (standard library and third-party) is checked against an allowlist before the
code runs. The default allowlist is empty, so even import json rejects the whole node:
TASK_RUNNERS.md). Some instances therefore allow json, datetime
and re, and most don't.import json + return [{"json": {"ok": True}}], or ask the user. Never
assume.{{ JSON.parse($json.payload) }} in Edit Fields).
Do date math in expressions (Luxon) or JS. ISO-8601 strings still compare and sort correctly as
plain strings. Use the Crypto node for hashing.requests, pandas and numpy are never available unless the admin built a custom runner
image. Use the HTTP Request node for HTTP.| You write | What happens | Use instead |
|---|---|---|
eval, exec, compile, open, input, type, getattr, setattr, hasattr, vars, dir, globals, locals, object, memoryview, breakpoint | NameError: name 'type' is not defined (runtime) | isinstance(x, dict); key in d / d.get(key) |
class Foo: ... | __build_class__ not found (runtime) | dicts + functions |
x.__class__, "{0.__class__}".format(x), __import__("json") | Security violations detected (whole node rejected before running) | — |
global counter inside a function | NameError: name 'counter' is not defined, because your code runs inside a wrapper function | nonlocal counter |
Everything else in plain Python works (verified): comprehensions, generators, lambdas, closures,
recursion, try/except, f-strings / .format() / %, sorted/min/max/sum/any/all/
enumerate/zip/round, sets, isinstance, print() (output goes to the browser console).
Observed on n8n 2.38.5. The auto-wrapping and passthrough behaviours below are undocumented and could change in a later release. Re-check with a test run after upgrading n8n.
Run Once for All Items
| Return | Result |
|---|---|
[{"json": {...}}, ...] | canonical, N items |
[{...}, ...] (plain dicts) | auto-wrapped under json, N items |
{"json": {...}} or a single plain dict | 1 item |
_items (mutated in place) | passthrough with your changes |
None / no return | error Cannot read properties of null (reading 'json') |
Run Once for Each Item
| Return | Result |
|---|---|
{"json": {...}}, a plain dict, or _item | 1 item |
None | the item is dropped (a built-in filter) |
| a list | error A 'json' property isn't a dictionary [item 0] |
Value conversion on output: tuple becomes a list, set becomes the string "{1, 2}",
and a datetime becomes str(dt) ("2026-09-16 10:18:00.025792", not ISO). Convert explicitly
(sorted(s), dt.isoformat()).
Prefer the explicit [{"json": ...}] in all-items mode and {"json": ...} in each-item mode.
The auto-wrapping works, but the explicit shape makes the intent obvious to the next reader.
onErrorA plain raise ValueError("bad row") fails the node with that message. When the node has an
onError continue mode, the three failure kinds behave differently (verified):
| Failure | continueErrorOutput | continueRegularOutput |
|---|---|---|
Runtime exception (raise, KeyError, NameError, denied builtin) | {"error": "<message>"} on the error output (main[1]) ✅ | {"error": "<message>"} on the main output |
Static rejection (Security violations detected: import, dunder) | node marked failed, but the input items, unchanged, go out the success output; main[1] stays empty | input items, unchanged, on the main output |
Bad return shape (list in each-item mode, None in all-items mode) | same: unchanged input on the success output | same |
The last two are silent-data traps: downstream nodes receive unprocessed input as if the code had run, and the execution still shows success. No error branch catches them. Prevent them (no imports unless confirmed, correct return shape) and confirm with a real test run, checking the Code node's status and output (see n8n-error-handling).
Other messages:
Python runner unavailable: Python 3 is missing from this system: the self-hosted instance has
no Python task runner (the stock image ships none). It's an infrastructure problem, not a code
problem. See n8n-self-hosting → TASK_RUNNERS.md.validate_node / validate_workflow catch a few Python mistakes (import requests, missing
return, return None). They do not catch _input/_json, dot access, blocked stdlib
imports, dunder access or classes. A test execution is the only reliable check.Each Python Code node costs roughly 0.4 s (about 1 s when the runner is cold), noticeably more than a JS Code node or an expression. Process lists in Run Once for All Items mode rather than per item, and don't chain several small Python nodes where one would do.
_items (all items) / _item (each item)._input, _json, _node, _now or _jmespath.import unless confirmed allowlisted on this instance.type(), getattr/hasattr or dunders. nonlocal instead of global.$jmespath, Luxon and the transform gatekeeper, often a better fit than any Code node._query, returns a string).# Run Once for Each Item
row = _item["json"]
return {"json": {**row, "name_upper": (row.get("name") or "").upper()}}Security violations detected
Line 1: Import of standard library module 'json' is disallowed. Allowed stdlib modules: none