🔧 n8n Complete Cheat Sheet

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based data format used for storing and exchanging data between systems. Think of it as a universal language for data.

JSON vs Other Formats

JSON Structure Breakdown

{
  "name": "John Doe",
  "age": 30,
  "isActive": true,
  "salary": null,
  "skills": [
    "JavaScript",
    "Python"
  ],
  "address": {
    "street": "123 Main St",
    "city": "New York"
  }
}

Data Types Explained

Real-World JSON Examples

{
  "userId": 12345,
  "username": "john_doe",
  "profile": {
    "firstName": "John",
    "lastName": "Doe",
    "email": "john@example.com",
    "preferences": {
      "theme": "dark",
      "notifications": true
    }
  },
  "roles": ["user", "admin"],
  "lastLogin": "2024-01-15T10:30:00Z"
}

{
  "status": "success",
  "data": [
    {
      "id": 1,
      "title": "Learn n8n",
      "completed": false,
      "createdAt": "2024-01-01T00:00:00Z"
    }
  ],
  "meta": {
    "total": 1,
    "page": 1,
    "limit": 10
  }
}

JSON & Expressions in n8n

OpenAI node showing how to access JSON data with expressions like {{ $json.postContent }}

JSON Manipulation in n8n

// Convert object to JSON string
{{ $json.data.toJsonString() }}

// Parse JSON string to object
{{ JSON.parse($json.jsonString) }}

// Check if field exists
{{ $json.field !== undefined }}

// Get all object keys
{{ Object.keys($json) }}

// Get array length
{{ $json.items.length }}

// Map over array (use normal JavaScript)
{{ $json.items.map(item => item.name) }}

// Filter array
{{ $json.items.filter(item => item.active) }}

// Merge objects
{{ Object.assign({}, $json, {newField: "value"}) }}

Common JSON Issues & Solutions

API Fundamentals

API (Application Programming Interface) is like a waiter in a restaurant - you tell the waiter what you want, they take your order to the kitchen, and bring back your food.

The API Request Journey

1. Client sends request - "I want user info for ID 123"
2. API processes request - Validates, authenticates, routes
3. Server handles logic - Database queries, calculations
4. Response sent back - User data or error message

HTTP Methods Explained

Understanding Request Structure

METHOD /endpoint HTTP/1.1
Host: api.example.com
Header-Name: Header-Value
Content-Type: application/json
Authorization: Bearer your_token
{
  "requestBody": "data"
}

Status Codes Explained

Authentication Explained

cURL Commands Breakdown

# Basic GET request
curl https://api.example.com/users
# GET with authentication
curl -H "Authorization: Bearer TOKEN" \
  https://api.example.com/users
# POST with JSON data
curl -X POST \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer TOKEN" \
  -d '{"name": "John", "email": "john@email.com"}' \
  https://api.example.com/users
# Save response to file
curl -o response.json https://api.example.com/data

Common API Patterns

HTTP Request Configuration Interface

Complete HTTP Request node configuration showing all available options and settings

Method Selection (As shown in dropdown)

URL Configuration (From URL field)

// Static URL (as shown)
https://example.com
// Dynamic URLs with expressions
https://api.example.com/users/{{ $json.userId }}
// DON'T add query parameters in URL // ❌
https://api.example.com/search?q=value
// ✅ Use the Query Parameters section instead

Query Parameters (As demonstrated)

The interface shows "Send Query Parameters" toggle enabled with an example:

// Example shown in interface:
q1=answer
Name: q1
Value: answer
// This creates:
https://example.com?q1=answer
// Dynamic query parameters
Name: search
Value: {{ $json.searchTerm }}
Name: limit
Value: {{ $json.pageSize || 10 }}
// Multiple parameters create:
// https://api.example.com?search=term&limit=10

Headers Configuration (From Headers section)

The interface shows "Send Headers" enabled with header1=value example:

// Example from interface
Name: header1
Value: value
// Real-world headers
Name: Authorization
Value: Bearer {{ $credentials.apiToken }}
Name: Content-Type
Value: application/json
Name: Accept
Value: application/json

Request Body (From Body section)

The interface shows JSON body type selected with a sample structure:

// Example from interface
{
  "key": 2
}

// Dynamic JSON body
{
  "userId": {{ $json.id }},
  "name": "{{ $json.fullName }}",
  "email": "{{ $json.email }}",
  "metadata": {{ JSON.stringify($json.metadata) }}
}

Authentication Options (From Auth dropdown)

The interface shows "None" selected, but other options include:

Body Content Types Available

The interface shows "JSON" selected, but you can choose:

• JSON: For API calls expecting JSON data
• Form-Data: For file uploads and multipart forms
• Form URL Encoded: For traditional form submissions
• Raw: For custom data formats (XML, text, etc.)

Testing Your Configuration

AI Agent Workflow Structure

Complete AI Agent workflow showing connections between Memory, Tools, Models, and Output Parsers

AI Agent Components Explained

Tool Integration Patterns

Prompt Structure Best Practices

System Prompt:
- Persona: Define AI's role and behavior
- Task: Specific objectives to accomplish
- Context: Background information and constraints
- Format: Expected output structure

User Input: {{ $json.userMessage }}

Tools Available:
- Google Sheets (read/write)
- Vector search via Pinecone
- Web APIs through MCP Client

Memory Management

Implementation Tips

• ✅ Use specific, clear prompts
• ✅ Implement proper error handling
• ✅ Set up rate limit management
• ✅ Test with various input types
• ✅ Monitor token usage costs
• ✅ Combine multiple tools for complex tasks

Workflow Control

Canvas Navigation

Node Operations

Trigger Nodes

Core Processing Nodes

Data Transformation

Basic Syntax

// Basic field access
{{ $json.fieldName }}

// Node reference
{{ $node["Node Name"].json.field }}

// Array access
{{ $json.items[0].name }}

// Process all array items (use normal JavaScript)
{{ $json.items.map(item => item.value) }}

Common Patterns

Built-in Variables

String Operations

// Transform case
{{ $json.text.toLowerCase() }}
{{ $json.text.toUpperCase() }}

// String manipulation
{{ $json.text.trim() }}
{{ $json.text.replace("old", "new") }}
{{ $json.text.substring(0, 10) }}

// Check content
{{ $json.email.includes("@gmail.com") }}
{{ $json.text.startsWith("Hello") }}

Node Settings

Error Handling

Workflow Creation Steps

1. Choose your trigger (Manual, Webhook, Schedule)
2. Add data source (HTTP Request, Database, File)
3. Transform data (Set, Code, IF nodes)
4. Add business logic (loops, conditions)
5. Output or action (Save, Send, Update)
6. Test with sample data
7. Add error handling
8. Save and activate

Debugging Tips

Performance Tips

• ⚡ Limit batch sizes for large datasets
• ⚡ Use filters early to reduce data volume
• ⚡ Optimize loops and conditions
• ⚡ Cache frequently used data
• ⚡ Use webhooks over polling when possible

Data Pinning for Cost Savings

Pinning data from HTTP Request to save API calls - notice "This data is pinned" indicator