Add conditional logic support in templates

[chhoumann]

Summary

Add conditional logic (if-then-else) support in QuickAdd templates to enable dynamic content based on variable values.

Problem

Currently, templates are static and cannot adapt based on:

• Variable values entered by users
• File properties or metadata
• Date/time conditions
• Other dynamic factors

Use Cases

• Show different content based on note type: {{IF:noteType==meeting}}## Attendees{{ELSE}}## Overview{{ENDIF}}
• Conditional sections: {{IF:priority==high}}⚠️ URGENT: {{ENDIF}}
• Date-based logic: {{IF:DATE:dddd==Monday}}## Weekly Review{{ENDIF}}
• Variable-dependent formatting: {{IF:project}}Project: {{project}}{{ENDIF}}

Proposed Syntax

{{IF:condition}}
  Content when true
{{ELSEIF:condition2}}
  Content when condition2 is true  
{{ELSE}}
  Default content
{{ENDIF}}

Supported Conditions

• Variable comparisons: variable==value, variable\!=value
• Existence checks: variable (true if defined and not empty)
• Date conditions: DATE:format==value
• Numeric comparisons: variable>5, variable<=10

Benefits

• More dynamic and intelligent templates
• Reduced need for multiple similar templates
• Better user experience with contextual content
• More powerful automation possibilities

Implementation Notes

• Parse template for conditional blocks before variable substitution
• Evaluate conditions and include/exclude content accordingly
• Compatible with existing format syntax
• Could be optional feature for performance

[TWDickson]

You can do this with Templater syntax:

---
title: "{{VALUE:subject}}"
creation_date:  "{{VALUE:entry_date}}"
tags: "{{VALUE:tags}}"
type: "journal_entry"
---
<%* if ("{{VALUE:subject}}" !== "") { %>
## {{VALUE:subject}}

<%* } -%>
{{VALUE:entry}}

The if is broken across lines note that for this the QuickAdd variables need to be quoted:

<%* if ("{{VALUE:subject}}" is JS Conditional ) { %>

My conditional content here

<%* } -%>  //Closing bracket with whitespace eating