The unless helper is the inverse of the if helper. It executes the block if the conditional value is empty or equal to 0.
Think of unless as “if not” - it’s particularly useful when you want to check if something is missing or empty.

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Basic Usage

{{#unless lead.phone}}
  Please provide a phone number for better communication.
{{/unless}}
If lead.phone is empty: 
Please provide a phone number for better communication.
If lead.phone exists, nothing will be rendered.

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With Else Block

Like the if helper, unless can include an else block: 
{{#unless quote.event_address}}
  Event location is pending
{{else}}
  Event location: {{quote.event_address}}
{{/unless}}
If quote.event_address is empty: 
Event location is pending
If quote.event_address exists: 
Event location: 123 Main St, Anytown, USA

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Common Use Cases

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Missing Contact Information

{{#unless lead.email}}
  {{#unless lead.phone}}
    No contact information provided.
  {{/unless}}
{{/unless}}

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Incomplete Quote Details

{{#unless quote.guest_count}}
  Guest count needs to be confirmed.
{{/unless}}

{{#unless quote.event_start_time}}
  Event start time is not set.
{{/unless}}

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Missing Company Information

{{#unless company.contact_phone}}
  Contact us at {{company.contact_email}}
{{else}}
  Call us at {{company.contact_phone}}
{{/unless}}

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Best Practices

  1. Use unless when checking for missing or empty values
  2. Consider using if when the logic is complex or needs multiple conditions
  3. Keep the logic simple and readable
  4. Test templates with both empty and filled data
Like the if helper, unless treats zero (0) as a falsy value. If you need to treat zero differently, consider using the if helper with includeZero=true.

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Comparison with If Helper

Here’s the same logic written with both unless and if: Using unless: 
{{#unless lead.company_name}}
  Individual client
{{else}}
  Corporate client: {{lead.company_name}}
{{/unless}}
Equivalent using if: 
{{#if lead.company_name}}
  Corporate client: {{lead.company_name}}
{{else}}
  Individual client
{{/if}}
Choose the one that makes your template more readable and intuitive.