Initial commit

2025-11-29 18:17:17 +08:00
commit 6062d3994e
39 changed files with 21748 additions and 0 deletions
--- a/skills/n8n-code-python/README.md
+++ b/skills/n8n-code-python/README.md
@@ -0,0 +1,386 @@
+# n8n Code Python Skill
+
+Expert guidance for writing Python code in n8n Code nodes.
+
+---
+
+## ⚠️ Important: JavaScript First
+
+**Use JavaScript for 95% of use cases.**
+
+Python in n8n has **NO external libraries** (no requests, pandas, numpy).
+
+**When to use Python**:
+- You have complex Python-specific logic
+- You need Python's standard library features
+- You're more comfortable with Python than JavaScript
+
+**When to use JavaScript** (recommended):
+- HTTP requests ($helpers.httpRequest available)
+- Date/time operations (Luxon library included)
+- Most data transformations
+- When in doubt
+
+---
+
+## What This Skill Teaches
+
+### Core Concepts
+
+1. **Critical Limitation**: No external libraries
+2. **Data Access**: `_input.all()`, `_input.first()`, `_input.item`
+3. **Webhook Gotcha**: Data is under `_json["body"]`
+4. **Return Format**: Must return `[{"json": {...}}]`
+5. **Standard Library**: json, datetime, re, base64, hashlib, etc.
+
+### Top 5 Error Prevention
+
+This skill emphasizes **error prevention**:
+
+1. **ModuleNotFoundError** (trying to import external libraries)
+2. **Empty code / missing return**
+3. **KeyError** (dictionary access without .get())
+4. **IndexError** (list access without bounds checking)
+5. **Incorrect return format**
+
+These 5 errors are the most common in Python Code nodes.
+
+---
+
+## Skill Activation
+
+This skill activates when you:
+- Write Python in Code nodes
+- Ask about Python limitations
+- Need to know available standard library
+- Troubleshoot Python Code node errors
+- Work with Python data structures
+
+**Example queries**:
+- "Can I use pandas in Python Code node?"
+- "How do I access webhook data in Python?"
+- "What Python libraries are available?"
+- "Write Python code to process JSON"
+- "Why is requests module not found?"
+
+---
+
+## File Structure
+
+### SKILL.md (719 lines)
+**Quick start** and overview
+- When to use Python vs JavaScript
+- Critical limitation (no external libraries)
+- Mode selection (All Items vs Each Item)
+- Data access overview
+- Return format requirements
+- Standard library overview
+
+### DATA_ACCESS.md (703 lines)
+**Complete data access patterns**
+- `_input.all()` - Process all items
+- `_input.first()` - Get first item
+- `_input.item` - Current item (Each Item mode)
+- `_node["Name"]` - Reference other nodes
+- Webhook body structure (critical gotcha!)
+- Pattern selection guide
+
+### STANDARD_LIBRARY.md (850 lines)
+**Available Python modules**
+- json - JSON parsing
+- datetime - Date/time operations
+- re - Regular expressions
+- base64 - Encoding/decoding
+- hashlib - Hashing
+- urllib.parse - URL operations
+- math, random, statistics
+- What's NOT available (requests, pandas, numpy)
+- Workarounds for missing libraries
+
+### COMMON_PATTERNS.md (895 lines)
+**10 production-tested patterns**
+1. Multi-source data aggregation
+2. Regex-based filtering
+3. Markdown to structured data
+4. JSON object comparison
+5. CRM data transformation
+6. Release notes processing
+7. Array transformation
+8. Dictionary lookup
+9. Top N filtering
+10. String aggregation
+
+### ERROR_PATTERNS.md (730 lines)
+**Top 5 errors with solutions**
+1. ModuleNotFoundError (external libraries)
+2. Empty code / missing return
+3. KeyError (dictionary access)
+4. IndexError (list access)
+5. Incorrect return format
+- Error prevention checklist
+- Quick fix reference
+- Testing patterns
+
+---
+
+## Integration with Other Skills
+
+This skill works with:
+
+### n8n Expression Syntax
+- Python uses code syntax, not {{}} expressions
+- Data access patterns differ ($ vs _)
+
+### n8n MCP Tools Expert
+- Use MCP tools to validate Code node configurations
+- Check node setup with `get_node_essentials`
+
+### n8n Workflow Patterns
+- Code nodes fit into larger workflow patterns
+- Often used after HTTP Request or Webhook nodes
+
+### n8n Code JavaScript
+- Compare Python vs JavaScript approaches
+- Understand when to use which language
+- JavaScript recommended for 95% of cases
+
+### n8n Node Configuration
+- Configure Code node mode (All Items vs Each Item)
+- Set up proper connections
+
+---
+
+## Success Metrics
+
+After using this skill, you should be able to:
+
+- [ ] **Know the limitation**: Python has NO external libraries
+- [ ] **Choose language**: JavaScript for 95% of cases, Python when needed
+- [ ] **Access data**: Use `_input.all()`, `_input.first()`, `_input.item`
+- [ ] **Handle webhooks**: Access data via `_json["body"]`
+- [ ] **Return properly**: Always return `[{"json": {...}}]`
+- [ ] **Avoid KeyError**: Use `.get()` for dictionary access
+- [ ] **Use standard library**: Know what's available (json, datetime, re, etc.)
+- [ ] **Prevent errors**: Avoid top 5 common errors
+- [ ] **Choose alternatives**: Use n8n nodes when libraries needed
+- [ ] **Write production code**: Use proven patterns
+
+---
+
+## Quick Reference
+
+### Data Access
+```python
+all_items = _input.all()
+first_item = _input.first()
+current_item = _input.item  # Each Item mode only
+other_node = _node["NodeName"]
+```
+
+### Webhook Data
+```python
+webhook = _input.first()["json"]
+body = webhook.get("body", {})
+name = body.get("name")
+```
+
+### Safe Dictionary Access
+```python
+# ✅ Use .get() with defaults
+value = data.get("field", "default")
+
+# ❌ Risky - may raise KeyError
+value = data["field"]
+```
+
+### Return Format
+```python
+# ✅ Correct format
+return [{"json": {"result": "success"}}]
+
+# ❌ Wrong - plain dict
+return {"result": "success"}
+```
+
+### Standard Library
+```python
+# ✅ Available
+import json
+import datetime
+import re
+import base64
+import hashlib
+
+# ❌ NOT available
+import requests  # ModuleNotFoundError!
+import pandas    # ModuleNotFoundError!
+import numpy     # ModuleNotFoundError!
+```
+
+---
+
+## Common Use Cases
+
+### Use Case 1: Process Webhook Data
+```python
+webhook = _input.first()["json"]
+body = webhook.get("body", {})
+
+return [{
+    "json": {
+        "name": body.get("name"),
+        "email": body.get("email"),
+        "processed": True
+    }
+}]
+```
+
+### Use Case 2: Filter and Transform
+```python
+all_items = _input.all()
+
+active = [
+    {"json": {**item["json"], "filtered": True}}
+    for item in all_items
+    if item["json"].get("status") == "active"
+]
+
+return active
+```
+
+### Use Case 3: Aggregate Statistics
+```python
+import statistics
+
+all_items = _input.all()
+amounts = [item["json"].get("amount", 0) for item in all_items]
+
+return [{
+    "json": {
+        "total": sum(amounts),
+        "average": statistics.mean(amounts) if amounts else 0,
+        "count": len(amounts)
+    }
+}]
+```
+
+### Use Case 4: Parse JSON String
+```python
+import json
+
+data = _input.first()["json"]["body"]
+json_string = data.get("payload", "{}")
+
+try:
+    parsed = json.loads(json_string)
+    return [{"json": parsed}]
+except json.JSONDecodeError:
+    return [{"json": {"error": "Invalid JSON"}}]
+```
+
+---
+
+## Limitations and Workarounds
+
+### Limitation 1: No HTTP Requests Library
+**Problem**: No `requests` library
+**Workaround**: Use HTTP Request node or JavaScript
+
+### Limitation 2: No Data Analysis Library
+**Problem**: No `pandas` or `numpy`
+**Workaround**: Use list comprehensions and standard library
+
+### Limitation 3: No Database Drivers
+**Problem**: No `psycopg2`, `pymongo`, etc.
+**Workaround**: Use n8n database nodes (Postgres, MySQL, MongoDB)
+
+### Limitation 4: No Web Scraping
+**Problem**: No `beautifulsoup4` or `selenium`
+**Workaround**: Use HTML Extract node
+
+---
+
+## Best Practices
+
+1. **Use JavaScript for most cases** (95% recommendation)
+2. **Use .get() for dictionaries** (avoid KeyError)
+3. **Check lengths before indexing** (avoid IndexError)
+4. **Always return proper format**: `[{"json": {...}}]`
+5. **Access webhook data via ["body"]**
+6. **Use standard library only** (no external imports)
+7. **Handle empty input** (check `if items:`)
+8. **Test both modes** (All Items and Each Item)
+
+---
+
+## When Python is the Right Choice
+
+Use Python when:
+- Complex text processing (re module)
+- Mathematical calculations (math, statistics)
+- Date/time manipulation (datetime)
+- Cryptographic operations (hashlib)
+- You have existing Python logic to reuse
+- Team is more comfortable with Python
+
+Use JavaScript instead when:
+- Making HTTP requests
+- Working with dates (Luxon included)
+- Most data transformations
+- When in doubt
+
+---
+
+## Learning Path
+
+**Beginner**:
+1. Read SKILL.md - Understand the limitation
+2. Try DATA_ACCESS.md examples - Learn `_input` patterns
+3. Practice safe dictionary access with `.get()`
+
+**Intermediate**:
+4. Study STANDARD_LIBRARY.md - Know what's available
+5. Try COMMON_PATTERNS.md examples - Use proven patterns
+6. Learn ERROR_PATTERNS.md - Avoid common mistakes
+
+**Advanced**:
+7. Combine multiple patterns
+8. Use standard library effectively
+9. Know when to switch to JavaScript
+10. Write production-ready code
+
+---
+
+## Support
+
+**Questions?**
+- Check ERROR_PATTERNS.md for common issues
+- Review COMMON_PATTERNS.md for examples
+- Consider using JavaScript instead
+
+**Related Skills**:
+- n8n Code JavaScript - Alternative (recommended for 95% of cases)
+- n8n Expression Syntax - For {{}} expressions in other nodes
+- n8n Workflow Patterns - Bigger picture workflow design
+
+---
+
+## Version
+
+**Version**: 1.0.0
+**Status**: Production Ready
+**Compatibility**: n8n Code node (Python mode)
+
+---
+
+## Credits
+
+Part of the n8n-skills project.
+
+**Conceived by Romuald Członkowski**
+- Website: [www.aiadvisors.pl/en](https://www.aiadvisors.pl/en)
+- Part of [n8n-mcp project](https://github.com/czlonkowski/n8n-mcp)
+
+---
+
+**Remember**: JavaScript is recommended for 95% of use cases. Use Python only when you specifically need Python's standard library features.