FPath

From JRapid

FPath is an XPath based language. It was created by JRapid to query property values in forms.

Contents 1 Usage: 2 Operators: 3 Example: 4 See also:

Usage:

FPath and XPath syntax are very similar. In the following section we describe the main differences.

For the following examples, the following XML will be used:

<?xml version="1.0" encoding="ISO-8859-1"?>

<bookstore>

<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>

<book>
  <title lang="eng">Learning XML</title>
  <price>39.95</price>
</book>

</bookstore>

• FPath expressions do not start with the root element.

e.g: Select the first book in the bookstore:

XPath expression: "/bookstore/book[1]"

FPath expression: "/book[1]"

Result:

<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>

• FPath expressions use '.' to access child elements.

e.g: Access the title of the first book:

XPath expression: "/bookstore/book[1]/title"

FPath expression: "book[1].title"

Result: "Harry Potter"

• FPath expressions use '[*]' to match all the children of an element.

e.g: Selecting all the books of the bookstore:

XPath expression: "/bookstore/book"

FPath expression: "book[*]"

Result:

<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>

<book>
  <title lang="eng">Learning XML</title>
  <price>39.95</price>
</book>

• The '.' FPath expression is resolved as '/@id

The '.' character is used when an entity is passed as parameter.

Operators:

FPath uses the same operators as XPath. A table with the available operators is listed below:

Operator	Description	Example	Return value
|	Computes two node-sets	//book | //cd	Returns a node-set with all book and cd elements
+	Addition	6 + 4	10
-	Subtraction	6 - 4	2
*	Multiplication	6 * 4	24
div	Division	8 div 4	2
=	Equal	price=9.80	true if price is 9.80 false if price is 9.90
!=	Not equal	price!=9.80	true if price is 9.90 false if price is 9.80
<	Less than	price<9.80	true if price is 9.00 false if price is 9.80
<=	Less than or equal to	price<=9.80	true if price is 9.00 false if price is 9.90
>	Greater than	price>9.80	true if price is 9.90 false if price is 9.80
>=	Greater than or equal to	price>=9.80	true if price is 9.90 false if price is 9.70
or	or	price=9.80 or price=9.70	true if price is 9.80 false if price is 9.50
and	and	price>9.00 and price<9.90	true if price is 9.80 false if price is 8.50
mod	Modulus (division remainder)	5 mod 2	1

Example:

In the following example an Invoice element with "id" = 2 is opened,

XML response for the Invoice /xml/Invoice/2 web service :

<invoice id="2" style="">
   <company id="14" style="">
      <name>Proda Software</name> 
   </company>
   <address>Cordoba 883</address> 
   <date>13/01/2010</date> 
   <subtotal>80</subtotal> 
   <discount>0</discount> 
   <total>80</total> 
   <orderDetail id="4" style="">
      <invoice id="2" style="">
         <company id="14" style="">
            <name>Proda Software</name> 
         </company>
      </invoice>
      <qty>1</qty> 
      <product id="3" style="">
         <name>Keyboard</name> 
      </product>
      <unitPrice>80</unitPrice> 
      <totalPrice>80</totalPrice> 
   </orderDetail>
</invoice>

• The "subtotal" value is the sum of all the "totalPrice" elements that are children of the "orderDetail" element.

<property calculated="sum(orderDetail[*].totalPrice)" label="Subtotal" name="subtotal" type="integer"/>

• The "total" value is calculated by substracting the discount from the "subtotal" value:

<property calculated="subtotal * (1 - 5 * discount div 100)" calculatedtrigger="onchange" label="Total" name="total"
 type="integer"/>

See also:

• XPath tutorial
• EL