Xsl null empty

Find centralized, trusted content and collaborate around the technologies you use most. Connect and share knowledge within a single location that is structured and easy to search. How can I check if a value is null or empty with XSL?

For example, if categoryName is empty? I'm using a when choosing construct. Edit : This covers the most likely interpretation, in my opinion, of "[not] null or empty" as inferred from the question, including it's pseudo-code and my own early experience with XSLT. For more details e. From Empty Element :. This is probably the simplest XPath expression the one in accepted answer provides a test for the opposite, and would be longer, if negated :.

The argument to the not function above is false exactly when there is no categoryName child "null" of the context item, or the single such categoryName child has string value -- the empty string. Do note : No conditionals are used at all. Learn more about the importance of avoiding conditional constructs in this nice Pluralsight course:.

NET: Control Flow ". In some cases, you might want to know when the value is specifically null, which is particularly necessary when using XML which has been serialized from. NET objects. While the accepted answer works for this, it also returns the same result when the string is blank or empty, i.

Sometimes it's necessary to know the exact state and you can't simply check if CategoryName is instantiated, because unlike say Javascript. I know this question is old, but between all the answers, I miss one that is a common approach for this use-case in XSLT development. To deal with all these cases using xsl:choose -style constructs, or in other words, imperatively, is quickly getting messy even more so if elements can be at different levels! A typical programming idiom in XSLT is using templates hence the T in XSLT , which is declarative programming, not imperative you don't tell the processor what to do, you just tell what you want output if certain conditions are met.

For this use-case, that can look something like the following:. This works with any XSLT version , because the first one above has a higher precedence it has a predicate. The "fall-through" matching template, the second one, catches anything that is not valid.

The third one then takes care of outputting the categoryName value in a proper way. Note that in this scenario there is no need to specifially match categories or category , because the processor will automatically process all children, unless we tell it otherwise in this example, the second and third template do not further process the children, because there is no xsl:apply-templates in them.

This approach is more easily extendible then the imperative approach, because it automically deals with multiple categories and it can be expanded for other elements or exceptions by just adding another matching template.

Programming without if-branches. Note: there is no such thing as null in XML. There is xsi:nil , but that is rarely used, especially rarely in untyped scenarios without a schema of some sort. If there is a possibility that the element does not exist in the XML I would test both that the element is present and that the string-length is greater than zero:.

I actually found it better just testing for string length since many times the field is not null, just empty. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 12 years, 8 months ago. While the accepted answer works for this, it also returns the same result when the string is blank or empty, i. Sometimes it's necessary to know the exact state and you can't simply check if CategoryName is instantiated, because unlike say Javascript.

If there is a possibility that the element does not exist in the XML I would test both that the element is present and that the string-length is greater than zero:. I know this question is old, but between all the answers, I miss one that is a common approach for this use-case in XSLT development.

To deal with all these cases using xsl:choose -style constructs, or in other words, imperatively, is quickly getting messy even more so if elements can be at different levels! A typical programming idiom in XSLT is using templates hence the T in XSLT , which is declarative programming, not imperative you don't tell the processor what to do, you just tell what you want output if certain conditions are met.

For this use-case, that can look something like the following:. This works with any XSLT version , because the first one above has a higher precedence it has a predicate. The "fall-through" matching template, the second one, catches anything that is not valid. The third one then takes care of outputting the categoryName value in a proper way.

Note that in this scenario there is no need to specifially match categories or category , because the processor will automatically process all children, unless we tell it otherwise in this example, the second and third template do not further process the children, because there is no xsl:apply-templates in them.

This approach is more easily extendible then the imperative approach, because it automically deals with multiple categories and it can be expanded for other elements or exceptions by just adding another matching template. Programming without if-branches. Share Copy sharable link for this gist. Learn more about clone URLs. Download ZIP. XSLT: Check if a string is null or empty. This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below.

To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters Show hidden characters. Copy link. Now I've put a condition to the second and is only running in case the first one failed Thanks again. Great, Thanks a lot.