CODEWITHSUNDEEP
xslttesting
eejai42
eejai42

Reputation: 746

XSLT: "test" results confusion

I'm finding that while this test returns true:

test="string-length(foo) = 0"

However, for some reason, both of these tests are returning false:

test="foo = ''"

test="foo = null"

Any idea what might be going on? Is there some other state that foo could be in that would result in a 0 length, while still not being equal to '' or null?

Additionally - if I output:

X<xsl:value-of select="foo" />X

outputs: XX

Upvotes: 1

Views: 140

Answers (2)

Michael Kay
Michael Kay

Reputation: 163262

If foo is an empty node-set then string(foo) is "", and string-length(foo) is zero, but foo = '' is false. XPath is full of surprises.

The explanation is that foo = "" doesn't mean string(foo) = "" as you might expect, but rather some $F in foo satisfies $F = "" (which you can write in full in XPath 2.0). And if foo is an empty set then the existential test is clearly false.

Upvotes: 2

Martin Honnen
Martin Honnen

Reputation: 167401

Well if you do test="foo = null" you compare the foo child element(s) of the context node to the null child element(s) of the context node.

Upvotes: 1

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