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Setting Default Product Variant

You can control which variant is selected by default in your product templates by implementing the getDefaultProductVariant hook in your JavaScript template object.

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Implementation

Add the following hook to your JavaScript template object: 
const templateObject = {
  // ... existing template configuration
  getDefaultProductVariant: (product) => {
    // Returns the first variant's ID by default
    return product.variants[0].id;
  }
  // ... rest of template configuration
};

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Customization Examples

You can customize the logic inside getDefaultProductVariant to select different variants based on your requirements. Here are some practical examples: 
// Example 1: Return first in-stock variant ID
getDefaultProductVariant: (product) => {
  const inStockVariant = product.variants.find(
    variant => variant.availableForSale && variant.quantityAvailable > 0
  );
  return (inStockVariant || product.variants[0]).id;
}

// Example 2: Return lowest priced variant ID
getDefaultProductVariant: (product) => {
  const lowestPriceVariant = product.variants.reduce((lowest, variant) => {
    return (!lowest || variant.price < lowest.price) ? variant : lowest;
  }, null);
  return lowestPriceVariant.id;
}

// Example 3: Return variant ID with specific option
getDefaultProductVariant: (product) => {
  const variantWithSize = product.variants.find(variant => 
    variant.selectedOptions.some(option => 
      option.name === 'Size' && option.value === 'Medium'
    )
  );
  return (variantWithSize || product.variants[0]).id;
}

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Parameters

The hook receives the following parameter:
  • product (Object): The full product object containing all product data including variants

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Return Value

The hook should return the variant ID (number) of the variant that you want to be selected by default when the product page loads.
If the getDefaultProductVariant function returns null, it will have no effect on the variant selection in the store. The default variant selection behavior will remain unchanged.

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Complete Example

Here’s a complete example showing how to implement the default variant selection: 
const productTemplate = {
  name: 'Product Template',
  getDefaultProductVariant: (product) => {
    // Find first available variant with quantity in stock
    const defaultVariant = product.variants.find(variant => 
      variant.availableForSale && 
      variant.quantityAvailable > 0 &&
      !variant.currentlyNotInStock
    );
    
    // Return the variant ID, falling back to first variant's ID if no available variants found
    return (defaultVariant || product.variants[0]).id;
  },
  // ... other template configuration
};
This implementation will return the ID of the first available variant with stock as the default variant when customers view your product pages.