Template System - Dynamic Notification Content

Templates in Echobell allow you to create dynamic, context-rich notifications by incorporating variables into your notification titles and bodies. This powerful feature enables personalized and informative alerts that adapt based on the trigger data, transforming generic notifications into actionable intelligence.

Instead of receiving a generic "Alert triggered" message, templates let you create specific notifications like "Production server CPU at 95%" or "Build #142 failed in deploy stage" - providing immediate context without requiring additional investigation.

Basic Template Syntax

In Echobell templates, you can use variables by wrapping them in double curly braces:

{{variableName}}

When a channel is triggered, these variables are replaced with actual values passed through the trigger. For example, if your title template is You have received ${{amount}} and you trigger the channel with an amount value of 100, the resulting notification will display as You have received $100.

Advanced Template Expressions

Echobell templates support a variety of expressions for more complex scenarios:

Accessing Object Properties

{{user.name}}
{{data["value"]}}

Accessing Array Elements

{{items[0]}}

Using Comparison Operators

{{status == "active"}}
{{age > 18}}

Logical Operators

{{isSubscribed && !isPaused}}
{{isUrgent || isHighPriority}}

All standard operators are supported: ==, !=, <, >, <=, >=, &&, ||, and !.

Template Variables from Different Triggers

Webhook Triggers

When triggering via webhook, you can provide variables through:

Query string parameters:

GET https://hook.echobell.one/t/<channel-token>?amount=100&status=complete

JSON body (for POST requests):

POST https://hook.echobell.one/t/<channel-token>
Content-Type: application/json

{
  "amount": 100,
  "status": "complete",
  "user": {
    "name": "John",
    "id": 12345
  }
}

Special variables:
- externalLink: Provides a clickable link in notification records
- bodyAsText: The plain text content of the request body if Content-Type is text/plain
- header: Gives access to HTTP request headers (e.g., {{header["content-type"]}})

Email Triggers

When a channel is triggered via email, the following variables are automatically available:

from: The sender's email address
to: The recipient's email address
subject: The email subject line
text: The plain text content of the email
html: The HTML content of the email

Template Use Cases

Comparisons and Booleans

Expressions that use comparison or logical operators render their boolean result as the text true or false:

Payment over $1000: {{amount > 1000}}
High priority: {{isUrgent || isImportant}}

Echobell templates do not support inline if/else (ternary) logic. To send different content in different situations, use channel Conditions to route triggers, or interpolate the raw values directly.

Channel Conditions

In addition to using templates in notification content, you can set Conditions in channel advanced settings that determine whether notifications should be sent at all. These conditions use the same expression syntax (without the curly braces).

For example, to only send notifications for amounts greater than a threshold:

amount > 100

Link Templates

Configure a custom link template in channel advanced settings to create clickable links in notification records:

https://dashboard.example.com/orders/{{orderId}}

If no link template is set, the value of the externalLink variable will be used by default.

System Time Variables (UTC)

These variables are always available to templates (and conditions) and are computed in UTC.

The following values are injected directly (flat) and can be used by name:

year, month (1–12)
dayOfMonth, dayOfWeek (0–6, Sunday = 0)
hour (0–23), minute, second
date (YYYY-MM-DD), time (HH:mm:ss)
iso: ISO‑8601 timestamp (e.g., 2025-05-06T12:34:56.789Z)

Other values are available only under the sys. namespace (they are not injected as flat names):

sys.timezone: Always "UTC"
sys.now: ISO‑8601 timestamp (same value as iso)
sys.epochMs, sys.epochSeconds: Current time since Unix epoch (number)
sys.monthName: Month name (January–December)
sys.dayOfWeekName: Day name (Sunday–Saturday)

The sys. namespace also mirrors every flat value (e.g. sys.year, sys.hour).

Examples:

Sent at {{date}} {{time}} {{sys.timezone}}
Today is {{sys.dayOfWeekName}}, {{sys.monthName}} {{dayOfMonth}}, {{year}}
Epoch: {{sys.epochSeconds}}

Best Practices

Handle Missing Variables

Echobell has no default-value operator. The || operator is purely logical — it evaluates both sides as booleans and renders true or false. So {{username || "Anonymous User"}} renders the literal text true or false, never the username or the fallback string.

When a variable is missing, {{variable}} simply renders as an empty string. Design your labels so an empty value still reads clearly:

User: {{username}}
Server: {{serverName}}
Errors detected: {{errorCount}}

If you need a guaranteed value, send it explicitly in the trigger payload rather than relying on a template fallback.

Informative Templates

Include key information in your templates to make notifications actionable without requiring additional context:

Good Examples:

Title: {{service}} {{status}} on {{environment}}
Body: {{errorMessage}} at {{timestamp}}
Action required: {{recommendedAction}}

Avoid:

Title: Alert
Body: Check logs

Keep Templates Concise

Notifications display best when titles and bodies are clear and to the point:

Titles: 3-8 words ideal, max 20 words
Bodies: 1-3 sentences ideal, avoid walls of text
Priority: Put most important information first

iOS notification constraints:

Title: ~40 characters visible in collapsed view
Body: ~60 characters in collapsed view, more when expanded

Use Consistent Naming

Maintain consistent variable naming across your channels:

Use clear, descriptive names: server_name not sn
Follow a convention: snake_case, camelCase, or kebab-case
Be consistent across related channels
Document expected variables for team members

Test Thoroughly

Test your templates with different variable combinations to ensure they render as expected:

Test with all variables present
Test with optional variables missing
Test with special characters and Unicode
Test with very long values
Test with empty strings
Test with numbers, booleans, arrays, and objects

Structure for Readability

Use formatting to make notification content easy to scan:

🚨 Alert: {{alertName}}
━━━━━━━━━━━━━━━
Server: {{server}}
Metric: {{metric}}  
Value: {{value}}
Time: {{time}}
━━━━━━━━━━━━━━━
Details: {{message}}

Or use simple labels:

Server: {{server}}
CPU Usage: {{cpu}}%
Memory: {{memory}}%
Status: {{status}}

Leverage Expressions

Use expressions to surface computed values and comparison results:

Title: {{service}} alert — critical: {{severity == "critical"}}
Body: {{metric}} is {{value}} (over threshold: {{value > threshold}})

Comparison and logical expressions render as true or false; pair them with static label text to convey meaning.

Consider Time Zones

Remember that system time variables are in UTC. Document this or convert in your templates:

Alert triggered at {{time}} UTC
Triggered: {{date}} {{time}} (UTC)

Common Patterns and Examples

Server Monitoring

Title: {{hostname}} - {{metric}} Alert
Body: {{metric}} on {{hostname}} is at {{value}}{{unit}}
Threshold: {{threshold}}{{unit}}
Time: {{date}} {{time}}

CI/CD Pipelines

Title: {{repository}} - Build {{status}}
Body: Build #{{buildNumber}} {{status}} in {{duration}}s
Branch: {{branch}}
Commit: {{commit_message}}
Author: {{author}}

E-commerce

Title: New Order #{{orderNumber}}
Body: Customer: {{customerName}}
Items: {{itemCount}} items
Total: ${{totalAmount}}
Shipping: {{shippingAddress}}

Error Tracking

Title: {{errorType}} in {{service}}
Body: {{errorMessage}}
File: {{filename}}:{{lineNumber}}
User: {{userId}}
Environment: {{environment}}

Advanced Features

Link Templates

Configure a custom link template in channel advanced settings to create clickable links in notification records:

https://dashboard.example.com/orders/{{orderId}}
https://grafana.example.com/d/{{dashboardId}}
https://github.com/{{repo}}/actions/runs/{{runId}}

If no link template is set, the value of the externalLink variable will be used by default. This is useful for providing quick access to relevant dashboards, logs, or documentation directly from the notification.

Showing Computed Values

Templates cannot branch with ternary (? :) logic, and there is no string concatenation operator (+). Instead, interpolate values and comparison results directly, using static text for labels:

Online: {{isOnline}}
High severity: {{severity > 5}}
Errors detected: {{count}}

Comparison expressions render as true or false. To send genuinely different messages per situation, route triggers with channel Conditions instead of branching inside a single template.

Channel Conditions

For example, to only send notifications for amounts greater than a threshold:

amount > 100
status == "critical"
temperature > 30 && location == "datacenter"

This prevents alert fatigue by filtering out non-critical events before notifications are sent. Learn more in our Conditions guide.

Webhook Integration - Learn how to pass variables via webhooks
Email Triggers - Variables available from email triggers
Conditions - Filter notifications with conditional expressions
Getting Started - Set up your first channel with templates

Troubleshooting

Template not rendering variables:

Check variable names match exactly (case-sensitive)
Verify variables are being passed in webhook/email trigger
Test with simple variables first, then add complexity

Variables showing as empty:

Confirm the variable exists in the trigger data
Check for typos in variable names
Verify JSON structure for nested properties

Expression errors:

Validate syntax with simple expressions first
Ensure operators are properly spaced
Check that property access uses correct syntax

Need help? Visit our Support Center or contact echobell@weelone.com.

Templates are a powerful way to create dynamic, informative notifications that give users exactly the information they need, when they need it. Start with simple variable substitution, then gradually add expressions and conditional logic to create sophisticated notification systems.

Basic Template Syntax

Advanced Template Expressions

Template Variables from Different Triggers

Webhook Triggers

Email Triggers

Template Use Cases

Comparisons and Booleans

Channel Conditions

Link Templates

System Time Variables (UTC)

Best Practices

Handle Missing Variables

Informative Templates

Keep Templates Concise

Use Consistent Naming

Test Thoroughly

Structure for Readability

Leverage Expressions

Consider Time Zones

Common Patterns and Examples

Server Monitoring

CI/CD Pipelines

E-commerce

Error Tracking

Advanced Features

Link Templates

Showing Computed Values

Channel Conditions

Related Documentation

Troubleshooting