Adobe Dreamweaver CC 2015 - Manual (Page 604)

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Dynamic sites, pages and web forms
Last updated 6/3/2015
Dreamweaver lets you develop code blocks that incorporate control statements that execute conditionally. The Server
Behavior Builder uses if, elseif, and else statements, and may also contain server behavior parameters. This enables you
to insert alternate text blocks based on the values of OR relationships among server behavior parameters.
The following example shows the if, elseif, and else statements. The square brackets ([ ]) denote optional code and the
asterisk (*) denotes zero or more instances. To execute a portion of a code block or the entire code block only if a certain
condition or conditions apply, use the following syntax:
<@ if (expression1) @> conditional
text1[<@ elseif (expression2) @> conditional text2]*[<@ else @>
conditional text3]<@ endif @>
Condition expressions can be any JavaScript expression that can be evaluated using the JavaScript eval() function, and
may include a server behavior parameter marked by @@’s. (The @@’s distinguish the parameter from JavaScript
variables and keywords.)
Effectively using conditional expressions
When using if, else, and elseif directives within the insertText XML tag, the participant text is preprocessed to resolve
the if directives and to determine which text to include in the result. The if and elseif directives take the expression as
an argument. The condition expression is the same as that for JavaScript condition expressions, and can also contain
server behavior parameters. Directives such as this allow you to choose between alternative code blocks based on the
values of, or relationships between, server behavior parameters.
For example, the following JSP code comes from a Dreamweaver server behavior that uses a conditional code block:
@@rsName@@.close();
<@ if (@@callableName@@ != '') @>
@@callableName@@.execute();
@@rsName@@ = @@callableName@@.getResultSet();<@ else @>
@@rsName@@ = Statement@@rsName@@.executeQuery();
<@ endif @>
@@rsName@@_hasData = @@rsName@@.next();
The conditional code block starts with <@ if (@@callableName@@ != '') @> and ends with <@ endif @>. According to
the code, if the user enters a value for the @@callableName@@ parameter in the server behavior's Parameter dialog
box—in other words, if the @@callableName@@ parameter value is not null, or (@@callableName@@ != '')—then the
conditional code block is replaced with the following statements:
@@callableName@@.execute();
@@rsName@@ = @@callableName@@.getResultSet();
Otherwise, the code block is replaced with the following statement:
@@rsName@@ = Statement@@rsName@@.executeQuery();
Positioning a code block
When you create code blocks using the Server Behavior Builder, you must specify where to insert them in the page’s
HTML code.
For example, if you insert a code block above the opening tag, you must then specify the code block’s position
relative to other tags, scripts, and server behaviors in that section of the page’s HTML code. Typical examples include
positioning a behavior either before or after any recordset queries that might also exist in the page code above the
opening tag.