Check Whether a String Contains Substring with Smarty: A Developer's Guide

Dealing with dynamic content within template engines like Smarty often requires robust string manipulation. When you are building complex systems, especially for critical communications like email templates in e-commerce platforms such as Shopware, the ability to conditionally display information based on partial matches is crucial.

I understand your predicament perfectly: you need a clean, scalable way to check if a variable, like $sDispatch.name, contains one of several possible keywords ("DHL", "DPD", "Deutsche Post") rather than requiring an exhaustive list of individual equality checks. While Smarty excels at conditional logic, it doesn't provide built-in fuzzy string matching functions directly, forcing us to leverage the underlying power of PHP within the template context.

As a senior developer, I can guide you toward the most efficient and cleanest solution using native PHP functions embedded within your Smarty templates.

The Challenge with Simple Equality Checks

Your initial approach relies on strict equality checks:

{if $sDispatch.name == "DHL national"}
    ...
{else if $sDispatch.name == "DPD"}
    ...
// ... and so on

This method is functional but quickly becomes unwieldy, repetitive, and hard to maintain as you add more dispatch options. If you have dozens of carriers, managing a long chain of if/else if statements inside your template can lead to bloated code that violates the DRY (Don't Repeat Yourself) principle.

The Developer Solution: Leveraging strpos()

The superior way to handle substring checking is by utilizing PHP’s string searching functions, specifically strpos() or stripos(). These functions allow you to determine if one string exists within another.

strpos($haystack, $needle) returns the position (index) of the first occurrence of the needle in the haystack. If the substring is not found, it returns false. We can leverage this boolean result directly within Smarty’s conditional structure.

Implementing Substring Logic in Smarty

Instead of checking for exact matches, we check if the string contains the target keyword. To make this efficient and readable in a template, we will use the logical OR operator (||) combined with strpos() checks.

Here is how you can refactor your logic to handle multiple dispatch options:

{if strpos($sDispatch.name, "DHL") !== false}
    <a href="https://sampleurl.com?trackingcode={$sOrder.trackingcode}">Track via DHL</a>
{elseif strpos($sDispatch.name, "DPD") !== false}
    <a href="https://sampleurl.com?trackingcode={$sOrder.trackingcode}">Track via DPD</a>
{elseif strpos($sDispatch.name, "Deutsche Post") !== false}
    <a href="http://sampleurl.com">Track via Deutsche Post</a>
{else}
    <p>Your order cannot be tracked at this time.</p>
{/if}

Explanation of the Code

1. strpos($sDispatch.name, "DHL"): This attempts to find the starting position of the substring "DHL" within the dispatch name.
2. !== false: If strpos() finds the substring, it returns an integer (the position), which is not equal to false. Therefore, if the condition is true (the string contains "DHL"), the entire expression evaluates to true, and the code block executes. If the substring is not found, strpos returns false, so the condition fails, and we move to the next elseif.
3. Readability: This approach cleanly separates the logic for each carrier, making your template significantly easier to read and maintain than a long chain of strict equality checks.

Best Practices and Framework Alignment

When working with templating languages, especially when dealing with dynamic data that originates from backend systems (like Shopware), it is essential to remember principles found in modern application development frameworks. Just as robust applications rely on tested methods for handling data flow—much like how the Laravel ecosystem emphasizes clean, testable code—your template logic should prioritize clarity and efficiency.

When you are building complex business logic that dictates what content is displayed, strive for modularity. If your checks become extremely numerous, consider moving this complex conditional mapping into a dedicated service or controller layer in your PHP backend before passing the final required variables to Smarty. This keeps the template focused purely on presentation while ensuring the underlying data validation remains secure and maintainable. For structured application development, focusing on clean architecture is key; think about how you structure your services, similar to the principles championed by organizations like Laravel.

Conclusion

By shifting your approach from strict string equality checks to utilizing PHP’s strpos() function within your Smarty conditionals, you achieve a more flexible, scalable, and readable solution for checking substring containment. This method allows you to handle multiple conditions elegantly, ensuring that your email templates remain clean, efficient, and easy to manage, no matter how many dispatch options you need to support.