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Zhongwei Li
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skills/n8n-expression-syntax/EXAMPLES.md
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skills/n8n-expression-syntax/EXAMPLES.md
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# n8n Expression Examples
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Real working examples from n8n workflows.
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---
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## Example 1: Webhook Form Submission
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**Scenario**: Form submission webhook posts to Slack
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**Workflow**: Webhook → Slack
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**Webhook Input** (POST):
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```json
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{
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"name": "John Doe",
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"email": "john@example.com",
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"company": "Acme Corp",
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"message": "Interested in your product"
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}
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```
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**Webhook Node Output**:
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```json
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{
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"headers": {"content-type": "application/json"},
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"params": {},
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"query": {},
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"body": {
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"name": "John Doe",
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"email": "john@example.com",
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"company": "Acme Corp",
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"message": "Interested in your product"
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}
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}
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```
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**In Slack Node** (text field):
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```
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New form submission! 📝
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Name: {{$json.body.name}}
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Email: {{$json.body.email}}
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Company: {{$json.body.company}}
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Message: {{$json.body.message}}
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```
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**Output**:
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```
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New form submission! 📝
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Name: John Doe
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Email: john@example.com
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Company: Acme Corp
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Message: Interested in your product
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```
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---
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## Example 2: HTTP API to Database
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**Scenario**: Fetch user data from API and insert into database
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**Workflow**: Schedule → HTTP Request → Postgres
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**HTTP Request Returns**:
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```json
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{
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"data": {
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"users": [
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{
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"id": 123,
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"name": "Alice Smith",
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"email": "alice@example.com",
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"role": "admin"
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}
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]
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}
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}
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```
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**In Postgres Node** (INSERT statement):
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```sql
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INSERT INTO users (user_id, name, email, role, synced_at)
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VALUES (
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{{$json.data.users[0].id}},
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'{{$json.data.users[0].name}}',
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'{{$json.data.users[0].email}}',
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'{{$json.data.users[0].role}}',
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'{{$now.toFormat('yyyy-MM-dd HH:mm:ss')}}'
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)
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```
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**Result**: User inserted with current timestamp
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---
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## Example 3: Multi-Node Data Flow
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**Scenario**: Webhook → HTTP Request → Email
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**Workflow Structure**:
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1. Webhook receives order ID
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2. HTTP Request fetches order details
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3. Email sends confirmation
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### Node 1: Webhook
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**Receives**:
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```json
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{
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"body": {
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"order_id": "ORD-12345"
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}
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}
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```
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### Node 2: HTTP Request
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**URL field**:
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```
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https://api.example.com/orders/{{$json.body.order_id}}
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```
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**Returns**:
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```json
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{
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"order": {
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"id": "ORD-12345",
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"customer": "Bob Jones",
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"total": 99.99,
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"items": ["Widget", "Gadget"]
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}
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}
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```
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### Node 3: Email
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**Subject**:
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```
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Order {{$node["Webhook"].json.body.order_id}} Confirmed
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```
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**Body**:
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```
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Dear {{$node["HTTP Request"].json.order.customer}},
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Your order {{$node["Webhook"].json.body.order_id}} has been confirmed!
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Total: ${{$node["HTTP Request"].json.order.total}}
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Items: {{$node["HTTP Request"].json.order.items.join(', ')}}
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Thank you for your purchase!
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```
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**Email Result**:
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```
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Subject: Order ORD-12345 Confirmed
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Dear Bob Jones,
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Your order ORD-12345 has been confirmed!
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Total: $99.99
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Items: Widget, Gadget
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Thank you for your purchase!
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```
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---
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## Example 4: Date Formatting
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**Scenario**: Various date format outputs
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**Current Time**: 2025-10-20 14:30:45
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### ISO Format
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```javascript
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{{$now.toISO()}}
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```
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**Output**: `2025-10-20T14:30:45.000Z`
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### Custom Date Format
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```javascript
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{{$now.toFormat('yyyy-MM-dd')}}
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```
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**Output**: `2025-10-20`
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### Time Only
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```javascript
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{{$now.toFormat('HH:mm:ss')}}
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```
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**Output**: `14:30:45`
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### Full Readable Format
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```javascript
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{{$now.toFormat('MMMM dd, yyyy')}}
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```
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**Output**: `October 20, 2025`
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### Date Math - Future
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```javascript
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{{$now.plus({days: 7}).toFormat('yyyy-MM-dd')}}
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```
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**Output**: `2025-10-27`
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### Date Math - Past
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```javascript
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{{$now.minus({hours: 24}).toFormat('yyyy-MM-dd HH:mm')}}
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```
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**Output**: `2025-10-19 14:30`
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---
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## Example 5: Array Operations
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**Data**:
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```json
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{
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"users": [
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{"name": "Alice", "email": "alice@example.com"},
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{"name": "Bob", "email": "bob@example.com"},
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{"name": "Charlie", "email": "charlie@example.com"}
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]
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}
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```
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### First User
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```javascript
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{{$json.users[0].name}}
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```
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**Output**: `Alice`
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### Last User
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```javascript
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{{$json.users[$json.users.length - 1].name}}
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```
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**Output**: `Charlie`
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### All Emails (Join)
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```javascript
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{{$json.users.map(u => u.email).join(', ')}}
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```
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**Output**: `alice@example.com, bob@example.com, charlie@example.com`
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### Array Length
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```javascript
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{{$json.users.length}}
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```
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**Output**: `3`
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---
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## Example 6: Conditional Logic
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**Data**:
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```json
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{
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"order": {
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"status": "completed",
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"total": 150
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}
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}
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```
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### Ternary Operator
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```javascript
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{{$json.order.status === 'completed' ? 'Order Complete ✓' : 'Pending...'}}
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```
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**Output**: `Order Complete ✓`
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### Default Values
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```javascript
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{{$json.order.notes || 'No notes provided'}}
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```
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**Output**: `No notes provided` (if notes field doesn't exist)
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### Multiple Conditions
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```javascript
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{{$json.order.total > 100 ? 'Premium Customer' : 'Standard Customer'}}
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```
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**Output**: `Premium Customer`
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---
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## Example 7: String Manipulation
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**Data**:
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```json
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{
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"user": {
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"email": "JOHN@EXAMPLE.COM",
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"message": " Hello World "
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}
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}
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```
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### Lowercase
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```javascript
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{{$json.user.email.toLowerCase()}}
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```
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**Output**: `john@example.com`
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### Uppercase
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```javascript
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{{$json.user.message.toUpperCase()}}
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```
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**Output**: ` HELLO WORLD `
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### Trim
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```javascript
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{{$json.user.message.trim()}}
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```
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**Output**: `Hello World`
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### Substring
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```javascript
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{{$json.user.email.substring(0, 4)}}
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```
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**Output**: `JOHN`
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### Replace
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```javascript
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{{$json.user.message.replace('World', 'n8n')}}
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```
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**Output**: ` Hello n8n `
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---
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## Example 8: Fields with Spaces
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**Data**:
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```json
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{
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"user data": {
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"first name": "Jane",
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"last name": "Doe",
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"phone number": "+1234567890"
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}
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}
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```
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### Bracket Notation
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```javascript
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{{$json['user data']['first name']}}
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```
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**Output**: `Jane`
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### Combined
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```javascript
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{{$json['user data']['first name']}} {{$json['user data']['last name']}}
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```
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**Output**: `Jane Doe`
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### Nested Spaces
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```javascript
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Contact: {{$json['user data']['phone number']}}
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```
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**Output**: `Contact: +1234567890`
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---
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## Example 9: Code Node (Direct Access)
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**Code Node**: Transform webhook data
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**Input** (from Webhook node):
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```json
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{
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"body": {
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"items": ["apple", "banana", "cherry"]
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}
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}
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```
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**Code** (JavaScript):
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```javascript
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// ✅ Direct access (no {{ }})
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const items = $json.body.items;
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// Transform to uppercase
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const uppercased = items.map(item => item.toUpperCase());
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// Return in n8n format
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return [{
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json: {
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original: items,
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transformed: uppercased,
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count: items.length
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}
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}];
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```
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**Output**:
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```json
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{
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"original": ["apple", "banana", "cherry"],
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"transformed": ["APPLE", "BANANA", "CHERRY"],
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"count": 3
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}
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```
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---
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## Example 10: Environment Variables
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**Setup**: Environment variable `API_KEY=secret123`
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### In HTTP Request (Headers)
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```javascript
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Authorization: Bearer {{$env.API_KEY}}
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```
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**Result**: `Authorization: Bearer secret123`
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### In URL
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```javascript
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https://api.example.com/data?key={{$env.API_KEY}}
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```
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**Result**: `https://api.example.com/data?key=secret123`
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---
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## Template from Real Workflow
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**Based on n8n template #2947** (Weather to Slack)
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### Workflow Structure
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Webhook → OpenStreetMap API → Weather API → Slack
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### Webhook Slash Command
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**Input**: `/weather London`
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**Webhook receives**:
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```json
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{
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"body": {
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"text": "London"
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}
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}
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```
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### OpenStreetMap API
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**URL**:
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```
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https://nominatim.openstreetmap.org/search?q={{$json.body.text}}&format=json
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```
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### Weather API (NWS)
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**URL**:
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```
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https://api.weather.gov/points/{{$node["OpenStreetMap"].json[0].lat}},{{$node["OpenStreetMap"].json[0].lon}}
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```
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### Slack Message
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```
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Weather for {{$json.body.text}}:
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Temperature: {{$node["Weather API"].json.properties.temperature.value}}°C
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Conditions: {{$node["Weather API"].json.properties.shortForecast}}
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```
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---
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## Summary
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**Key Patterns**:
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1. Webhook data is under `.body`
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2. Use `{{}}` for expressions (except Code nodes)
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3. Reference other nodes with `$node["Node Name"].json`
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4. Use brackets for field names with spaces
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5. Node names are case-sensitive
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**Most Common Uses**:
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- `{{$json.body.field}}` - Webhook data
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- `{{$node["Name"].json.field}}` - Other node data
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- `{{$now.toFormat('yyyy-MM-dd')}}` - Timestamps
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- `{{$json.array[0].field}}` - Array access
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- `{{$json.field || 'default'}}` - Default values
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---
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**Related**: See [COMMON_MISTAKES.md](COMMON_MISTAKES.md) for error examples and fixes.
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