Weird behavior of the XPath operator

Question

I m attempting to create an xsl choose statement with multiple conditions to test   So far  I have this    lt xsl choose gt       lt xsl when test   AccountNumber     12345  and  Balance     0   gt          lt do stuff here gt               The problem is that the  and  is being treated as an  or    If the account number is 12345 or the balance of an account is 0  the condition is treated as true and the  code gets executed   I need the test to be that both conditions must be true    do I have the syntax wrong here   Thanks in advance   Tim

User · Answer

The problem is that the  and  is being treated as an  or     No  the problem is that you are using the XPath    operator and you aren t aware of its  weird  semantics   Solution   Just replace the any x    y expressions with a not x   y  expression   In your specific case   Replace    lt xsl when test   AccountNumber     12345  and  Balance     0   gt    with    lt xsl when test  not  AccountNumber    12345   and not  Balance    0    gt    Explanation   By definition whenever one of the operands of the    operator is a nodeset  then the result of evaluating this operator is true if there is a node in the node-set  whose value isn t equal to the other operand   So     someNodeSet     someValue   generally doesn t produce the same result as    not  someNodeSet    someValue    The latter  by definition  is true exactly when there isn t a node in  someNodeSet whose string value is equal to  someValue   Lesson to learn   Never use the    operator  unless you are absolutely sure you know what you are doing

User · Answer

If  AccountNumber or  Balance is a node-set  then this behavior could easily happen   It s not because and is being treated as or   For example  if  AccountNumber referred to nodes with the values 12345 and 66 and  Balance referred to nodes with the values 55 and 0  then  AccountNumber     12345  would be true  because 66 is not equal to 12345  and  Balance     0  would be true  because 55 is not equal to 0    I d suggest trying this instead    lt xsl when test  not  AccountNumber    12345  or  Balance    0    gt     AccountNumber    12345  or  Balance    0  will be true any time there is an  AccountNumber with the value 12345 or there is a  Balance with the value 0  and if you apply not   to that  you will get a false result

User · Answer

I ve always used this syntax  which yields more predictable results than using       lt xsl when test  not  AccountNumber    12345   and not  Balance    0      gt

[xslt] Weird behavior of the != XPath operator

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