HP e-CommerceXML Accelerator sa7150 - Manual (Page 33)

C H A P T E R 3 XML Operations
23
Filters
Filters are identified by a FilterExpression enclosed within square
brackets, [ ]. These define a pattern within a pattern following this
general structure:
( (’/’ | ’//’) Element )? [ FilterExpression
]
Filter expressions are applied to every element returned by the
preceding path pattern. They return a match if the server is a valid
choice according to the filter expression.
The operative component of a FilterExpression is a comparison
expression or any FunctionCall expression that returns a string value,
which compares either an element or an attribute against a specified
value. An element in a FilterExpression refers to the child element of
the context node, while an attribute refers to the attribute of the
context node.
Comparison expression syntax:
(Element | Attribute | FunctionCall)
ComparisonOperator Value
FunctionCall expression syntax:
FunctionName ’(’ (Argument (’,’ Argument)*)?
’)’
You can combine comparison expressions and the FunctionCall
expression with Boolean operators and parentheses to create complex
filter expressions.
Sample Pattern Description
//PurchaseOrder
[Amount > 10000] Matches a PurchaseOrder element with a child element Amount
value greater than 10000
//PurchaseOrder
[@CustomerID > 9000] Matches a PurchaseOrder element with an attribute
CustomerID value greater than 9000
//PurchaseOrder
[Amount > 10000 and
@CustomerID > 9000] Matches a PurchaseOrder element with a child element Amount
value greater than 10000 and with an attribute CustomerID value
greater than 9000
Comparison Expression Samples