Does Xpath standard support null value in attribute

for example is the following xpath string v开发者_如何学运维alid:

/web:input_text[@value=null]

which means the element doest not has a value attribute.

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This XPath returns web:input_text which don't have value attribute:

/web:input_text[not(@value)]

XPath /web:input_text[@value=null] selects web:input_text which have value of value attribute = null node.

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Try /web:input_text[not(@value)] instead.