Price history chart

The price history chart visualizes a product’s price changes as a compact SVG sparkline chart. Customers can see how the price changed over a chosen period (30, 90 or 180 days), which builds transparency and trust in promotions.

Enabling the module

Go to WooCommerce > Polski > Store modules and enable Price history chart. The chart appears automatically on product pages that have a saved price history.

Requirement

The module requires the Omnibus module (Omnibus directive) to be enabled, as it saves the price history in the database. Without it, the chart will have no data to display.

Features

• Sparkline chart rendered as SVG (no dependency on JS libraries)
• Configurable periods: 30, 90 or 180 days
• Display of the minimum and maximum price in the period
• Gradient fill below the chart line
• Dot indicating the current price
• Chart colors configurable in the settings
• Automatic data retrieval from the Omnibus repository

Settings

Configuration in WooCommerce > Polski > Store modules > Price history chart.

Setting	Default	Description
days	30	Chart period in days: 30, 90 or 180
show_min_max	true	Display the minimum and maximum price below the chart
color	#2563eb	Color of the chart line and gradient

Database option: polski_price_history.

Chart appearance

The chart consists of the following elements:

• Line - the price trend over time (SVG stroke)
• Gradient - semi-transparent fill from the line to the bottom of the chart
• Dot - the product’s current price (the last point on the chart)
• Min/Max - labels with the minimum and maximum price (optional)

The chart size adapts to its container. The default height is 60px.

Technical details

Data source

The chart retrieves data from the OmnibusPriceRepository class, which stores the history of price changes required by the Omnibus directive. Each data point contains a date and a product price.

For variable products the chart is generated for the currently selected variation (updated via JavaScript after a variation change).

SVG rendering

The chart is rendered server-side as inline SVG, no external libraries, no HTTP requests, no JavaScript for drawing. As a result the chart:

• Displays instantly (no flash of unstyled content)
• Is accessible to screen readers (aria-label)
• Does not affect Core Web Vitals

Hooks

// Change the chart period dynamically
add_filter('polski/price_history/days', function (int $days, int $product_id): int {
    // Longer period for seasonal products
    if (has_term('seasonal', 'product_cat', $product_id)) {
        return 180;
    }
    return $days;
}, 10, 2);

// Change the chart position on the product page
add_filter('polski/price_history/hook', function (): string {
    return 'woocommerce_single_product_summary'; // default: woocommerce_product_meta_start
});

// Change the hook priority
add_filter('polski/price_history/hook_priority', function (): int {
    return 25;
});

// Filter the chart data
add_filter('polski/price_history/data', function (array $prices, int $product_id): array {
    return $prices;
}, 10, 2);

CSS classes

• .polski-price-history - main container
• .polski-price-history__chart - SVG element
• .polski-price-history__label - min/max labels
• .polski-price-history__min - minimum price
• .polski-price-history__max - maximum price

.polski-price-history {
    margin: 1rem 0;
    padding: 0.75rem;
    background: #f9fafb;
    border-radius: 0.5rem;
}

Module ID

price_history_chart

Troubleshooting

The chart does not display - check whether the Omnibus module is enabled and whether the product has a saved price history. New products will not have a chart until their first price change.

The chart is empty/flat - if the price did not change during the chosen period, the chart shows a flat line. This is correct behavior.

The chart colors do not match the theme - change the color in the module settings or override it in CSS: .polski-price-history__chart path { stroke: #your-color; }.

Report issues: github.com/wppoland/polski/issues

This page is for informational purposes only and does not constitute legal advice. Consult a lawyer before implementation. Polski for WooCommerce is open source software (GPLv2) provided without warranty.