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XPath supported syntax

XPath notations used in EBX.Platform must conform to the abbreviated syntax of XML Path Language (XPath) Version 1.0 , with some restrictions. This document details which abbreviated syntax is actually supported.

The XPath general expression is: localisation [ predicate ]

• Examples
• XPath expression syntax specification
  • General
  • Predicate
  • Extraction of foreign keys

Examples

Absolute path localisation:

/library/books/

Relative path localisations:

./Author

../Title

Root and descendant path localisations:

//books

Table path localisations with predicate:

../../books/[author_id = 0101 and (publisher = 'harmattan')]

/library/books/[not(publisher = 'dumesnil')]

Complex predicates:

starts-with(col3,'xxx') and ends-with(col3,'yyy') and not(osd:is-null(./col3))

contains(col3 ,'xxx') and ( not(col1=100) and date-greater-than(col2,'2007-12-30')

XPath expression syntax specification

General

Expression	Composition	Note/example
XPath expression	<container path>[predicate]	/books[title='xxx']
<container path>	<absolute path> | <relative path>
<absolute path>	/a/b | //b	//books
<relative path>	../../b | ./b | b	../../books

Predicate

Expression	Composition	Note/example
<predicate>	Ex: A and ( B or not(C) ) A,B,C: <atomic expression>	Composition of: logical operators braces, not() and atomic expressions.
<atomic expression>	<path><comparator><criterion> |method(<path>,<criterion>)	royalty = 24.5 starts-with(title, 'Johnat')booleanValue = true
<path>	<relative path>	Relative to the table wich contains it../authorstitle
<comparator>	<boolean comparator> | <numeric comparator> | <string comparator>
<boolean comparator>	=, !=
<numeric comparator>	=, !=, <, >, <=, >=
<string comparator>	=
<method>	<date method > | <string method > | osd:is-null method
<date, time & dateTime method >	date-less-than, date-equal, date-greater-than
<string method >	matches, starts-with, ends-with, contains
<criterion>	<boolean criterion> | <numeric criterion> | <string criterion> | <date criterion> | <time criterion> | <dateTime criterion>
<boolean criterion>	true, false
<numeric criterion>	integer or decimal	-4.6
<string criterion>	Quoted character string	'azerty'
<date criterion>	Quoted formated: 'yyyy-MM-dd'	'2007-12-31'
<time criterion>	Quoted formated: 'HH:mm:ss' or 'HH:mm:ss.SSS'	'11:55:00'
<dateTime criterion>	Quoted formated: 'yyyy-MM-ddTHH:mm:ss' or 'yyyy-MM-ddTHH:mm:ss.SSS'	'2007-12-31T11:55:00'

Extraction of foreign keys

In EBX.Platform, the foreign keys are grouped in a single field with the osd:tableRef declaration. The standard XPath syntax is augmented so as to extract the value of any targeted primary key field.

For example, if the table /root/tableA has a tableRef field named fkB whose target is /root/tableB and the primary key of tableB has two fields, id of type xs:int and date of type xs:date, then the following expressions will be valid:

• /root/tableB[ fkB = '123|2008-01-21' ], the string "123|2008-01-21" being a representation of the whole primary key value, but the next way is more efficient;

• /root/tableB[ fkB/id = 123 and date-equal(fkB/date, '2008-01-21') ], this version being equivalent to the previous and also more effficient;

• /root/tableB[ fkB/id >= 123 ], every number operator could be used here, since the targeted primary key field is of type xs:int;

• /root/tableB[ date-greater-than( ./fkB/date, '2007-01-01' ) ], every date operator could be used here, since the targeted primary key field is of type xs:date;

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