Templates are where raw station data becomes a readable web page. GraphWeather’s template engine replaces variable placeholders with live data at each publish cycle, generating static HTML that gets uploaded via FTP. Understanding the variable system, conditional logic, and format specifiers is essential for building custom station pages that display the information you care about. This guide covers the template system in depth, building on the foundational patterns in Publishing Fundamentals.

Variable Syntax

Template variables use delimiter-wrapped names that the engine recognises and replaces. Depending on the GraphWeather version, the syntax may use angle-bracket-percent or double-curly-brace notation:

<!-- Angle-bracket style -->
<span>Temperature: <%outdoor_temp%> °C</span>

<!-- Curly-brace style -->
<span>Temperature: {{outdoor_temp}} °C</span>

Both styles work the same way. The engine scans the template file, finds delimited tokens, looks up the current value, and writes the result. If a variable name is not recognised, the behaviour depends on configuration: some setups leave the token as-is (useful for debugging), while others replace it with an empty string or a placeholder like “N/A”.

Core Variables

Conditional Blocks

Templates support conditional logic for threshold-based display. For example, showing a frost warning when temperature drops below zero:

<%if outdoor_temp < 0%>
  <div class="alert">⚠️ Frost warning: <%outdoor_temp%> °C</div>
<%endif%>

Conditions can use comparison operators (<, >, ==, !=) and combine with AND / OR logic. Nested conditions are supported but should be used sparingly — deeply nested templates become difficult to maintain.

Format Specifiers

Control decimal places and formatting with specifiers appended to variable names:

• <%outdoor_temp:.1f%> — one decimal place (e.g., 22.5)
• <%barometer:.0f%> — no decimal places (e.g., 1013)
• <%wind_speed:.2f%> — two decimal places (e.g., 12.45)
• <%last_update:datetime%> — formatted date/time string

Multi-Language Output

For stations serving audiences in multiple languages, GraphWeather supports generating multiple output files from separate templates. Configure each template with language-specific labels and upload them to separate directories or filenames:

/weather/index_en.html  ← English template
/weather/index_fr.html  ← French template

Variable values (numbers, dates) can be formatted according to locale settings. Text labels are part of the template HTML, so each language file contains its own labels.

Troubleshooting Matrix

FAQ