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| <!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V1.0//EN" "../../dtd/document-v10.dtd"> |
| <document> |
| <header> |
| <title>Advanced Control Flow</title> |
| <authors> |
| <person name="Christopher Oliver" email="coliver@apache.org"/> |
| <person name="Ovidiu Predescu" email="ovidiu@apache.org"/> |
| </authors> |
| </header> |
| <body> |
| <s1 title="JPath Logic Sheet"> |
| <p> |
| The JPath Logic Sheet is an <link href="../xsp/index.html">XSP</link> logic sheet that allows |
| you to access data from a Cocoon Flowscript in an XSP page and inject it into a Cocoon |
| pipeline. It provides a set of tags (similar to the those defined by |
| <link href="http://www.w3.org/TR/xslt">XSLT</link>) that allow you to iterate over Java |
| collections (and Java or JavaScript arrays) and to test for the presence of optional or |
| alternate bean properties. It is based on |
| <link href="http://jakarta.apache.org/commons/jxpath">Apache JXPath</link>. |
| </p> |
| </s1> |
| <s1 title ="Tags"> |
| <p>The JPath tags are defined in the namespace</p> |
| <source>http://apache.org/xsp/jpath/1.0</source> |
| <s2 title ="if"> |
| <p>The <code>if</code> tag allows the conditional execution of its body according to value of its <code>test</code> attribute:</p> |
| <source> |
| <if test="XPathExpression"> |
| body |
| </if> |
| </source> |
| <p>Example:</p> |
| <source> |
| <jpath:if test="cart/numberOfItems = 0"> |
| Your cart is empty |
| </jpath:if> |
| </source> |
| </s2> |
| <s2 title ="choose"> |
| <p>The <code>choose</code> tag performs conditional block execution by its embedded |
| <code>when</code> sub tags. It renders the body of the first <code>when</code> tag whose |
| <code>test</code> condition evaluates to true. If none of the <code>test</code> conditions |
| of its nested <code>when</code> tags evaluate to <code>true</code>, then the body of its |
| <code>otherwise</code> tag is evaluated, if present:</p> |
| <source> |
| <choose> |
| <when test="XPathExpression"> |
| body |
| </when>+ |
| <otherwise> |
| body |
| </otherwise>? |
| </choose> |
| </source> |
| <p>Example:</p> |
| <source> |
| <choose> |
| <when test="not(user/loggedIn)"> |
| You're not logged in |
| </when> |
| <otherwise> |
| You're already logged in |
| </otherwise> |
| </choose> |
| </source> |
| </s2> |
| <s2 title="value-of"> |
| <p>The <code>value-of</code> tag evaluates an expression and outputs the result of the evaluation:</p> |
| <source> |
| <value-of select="XPathExpression"/> |
| </source> |
| <p>Example:</p> |
| <source> |
| <value-of select="cart/numberOfItems"> |
| </source> |
| </s2> |
| <s2 title="for-each"> |
| <p>The <code>for-each</code> tag allows you to iterate over a collection of objects:</p> |
| <source> |
| <for-each select="XPathExpression"> |
| body |
| </for-each> |
| </source> |
| <p>When using XPath expressions within <code>for-each</code> the current element is the |
| context node and can be referenced with XPath dot operator:</p> |
| <source>.</source> |
| <p>Example:</p> |
| <source> |
| <for-each select="cart/cartItems[position() <= $count]"> |
| <td><value-of select="./productId"></td> |
| </for-each> |
| </source> |
| </s2> |
| <s2 title="continuation"> |
| <p>The <code>continuation</code> tag returns the id of the current web continuation of your |
| Flowscript. You can refer to previous continuations by supplying the optional |
| <code>level</code> attribute. Zero is the current level, <code>-1</code> refers to the |
| previous continuation, and so on.</p> |
| <source> |
| <continuation [level="Number"]/> |
| </source> |
| <p>Example:</p> |
| <source> |
| <xsp:attribute name="action"><xsp:expr><jpath:continuation/>+".form"</xsp:expr></xsp:attribute> |
| </source> |
| </s2> |
| </s1> |
| </body> |
| </document> |
