The 15 most important Power Automate expression functions such as concat, formatDateTime and coalesce, explained with German practical examples.
The most important expression functions in Power Automate are concat, toUpper, toLower, replace and substring for text, utcNow, formatDateTime, addDays and dayOfWeek for date and time, if, equals, coalesce and empty for logic checks, and first and length for accessing lists and arrays. These 15 functions cover most text building blocks, date calculations and conditions in a cloud flow without you having to add extra actions. Each function is entered in the expression editor and can be nested with other functions, for example formatDateTime(utcNow(), 'dd.MM.yyyy') for a German date format. As of: July 2026.
Text functions join strings together, convert upper and lower case, or cut parts out of a string. They form the basis of almost every subject line, file name, or message in a flow.
Date and time functions provide the current timestamp, format it for display, and shift it by days or weeks. Power Automate works in UTC by default.
Logic functions check conditions and return different values depending on the result, without you having to create a separate branch in the flow.
Collection functions work equally on arrays and strings and are especially useful in loops when you need individual elements instead of the entire list.
Once you have tried out these 15 functions in your own examples, most flow problems can be solved without additional third-party connectors. For teams who prefer to build their flows with a fixed price and a direct contact person instead of doing it themselves, NordFlux provides support with Power Automate consulting from the first expression to the productive flow.
In the flow designer, open the "Expression" tab via the function icon (fx) or the expression editor of a field, and type the function directly there. Alternatively, insert dynamic content via the editor and wrap it with a function such as formatDateTime() or concat(). The editor flags syntax errors already while you type, so missing parentheses can be found quickly.
This is usually due to a mix-up of upper and lower case in the format string: MM stands for the month, mm for minutes, and dd for the day. A format such as 'mm/DD/yyyy' swaps minutes and day and thereby produces an obviously incorrect date. Check the format string against the .NET format characters linked by Microsoft Learn.
Yes, this is even the standard case for more complex expressions. One example is formatDateTime(addDays(utcNow(), 7), 'dd.MM.yyyy'), which outputs a due date in one week directly in the desired German format. Evaluation happens from the inside out, similar to nested formulas in Excel.
coalesce() checks exclusively for null and does not automatically skip empty strings, while a combination of if() and empty() can additionally treat empty strings as "no value". For simple default values on missing fields, coalesce() is sufficient; for stricter validation of required fields, the combination with empty() is the more robust choice.
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Learning the 15 core expressions is one thing, but real flows with nested conditions and shifting data formats get complex fast. NordFlux builds robust expressions that stay stable even with edge cases and faulty input data, instead of breaking the first time they hit production. In an initial conversation, we look at your trickiest expression cases together.
