Dreamweaver

Repeating code blocks with the loop directive

To repeat a portion of a code block or the entire code block a number of times, use the following syntax:

<@ loop (@@param1@@,@@param2@@) @>	code
block<@ endloop @>
When creating server behaviors, you can use looping constructs to repeat a code block a specified number of times. 
<@ loop (@@param1@@,@@param2@@,@@param3@@,@@param_n@@) @>	code block
<@ endloop @>
The loop directive accepts a comma-separated list of parameter arrays as arguments. In this case, parameter array arguments allow a user to supply multiple values for a single parameter. The repeating text is duplicated n times, where n is the length of the parameter array arguments. If more than one parameter array argument is specified, all the arrays must have the same length. On the ith evaluation of the loop, the ith elements of the parameter arrays replace the associated parameter instances in the code block.

When you create a dialog box for the server behavior, you can add a control to the dialog box that lets the page designer create parameter arrays. Dreamweaver includes a simple array control that you can use to create dialog boxes. This control, called Text Field Comma Separated List, is available through the Server Behavior Builder. To create user interface elements of greater complexity, see the API documentation to create a dialog box with a control to create arrays (a grid control, for example).

You can nest any number of conditionals or a loop directive within a conditional directive. For example, you can specify that if an expression is true to execute a loop.

The following example shows how such repeating code blocks can be used to create server behaviors (the example is a ColdFusion behavior used to access a stored procedure):

<CFSTOREDPROC procedure="AddNewBook"
	datasource=#MM_connection_DSN# 
	username=#MM_connection_USERNAME# 
	password=#MM_connection_PASSWORD#>
<CFPROCPARAM type="IN" dbvarname="@CategoryId" value="#Form.CategoryID#"
	cfsqltype="CF_SQL_INTEGER">
<CFPROCPARAM type="IN" dbvarname="@ISBN" value="#Form.ISBN#"
	cfsqltype="CF_SQL_VARCHAR">
</CFSTOREDPROC>

In this example, the CFSTOREDPROC tag can include zero or more CFPROCPARAM tags. However, without support for the loop directive, there is no way to include the CFPROCPARAM tags within the inserted CFSTOREDPROC tag. If this were to be created as a server behavior without the use of the loop directive, you would need to divide this example into two participants: a main CFSTOREDPROC tag, and a CFPROCPARAM tag whose participant type is multiple.

Using the loop directive, you can write the same procedure as follows:

<CFSTOREDPROC procedure="@@procedure@@"
datasource=#MM_@@conn@@_DSN#
username=#MM_@@conn@@_USERNAME# 
password=#MM_@@conn@@_PASSWORD#>
<@ loop (@@paramName@@,@@value@@,@@type@@) @>
	<CFPROCPARAM type="IN" 
	dbvarname="@@paramName@@"
	value="@@value@@" 
	cfsqltype="@@type@@">
<@ endloop @>
</CFSTOREDPROC>
Note: New lines after each “@>” are ignored.

If the user entered the following parameter values in the Server Behavior Builder dialog box:

procedure = "proc1"
conn = "connection1"
paramName = ["@CategoryId", "@Year", "@ISBN"]
value = ["#Form.CategoryId#", "#Form.Year#", "#Form.ISBN#"]
type = ["CF_SQL_INTEGER", "CF_SQL_INTEGER", "CF_SQL_VARCHAR"]

The server behavior would insert the following run-time code in the page:

<CFSTOREDPROC procedure="proc1"
datasource=#MM_connection1_DSN#
username=#MM_connection1_USERNAME# 
password=#MM_connection1_PASSWORD#>
<CFPROCPARAM type="IN" dbvarname="@CategoryId" value="#Form.CategoryId#"
	cfsqltype="CF_SQL_INTEGER">
<CFPROCPARAM type="IN" dbvarname="@Year" value="#Form.Year#"
	cfsqltype="CF_SQL_INTEGER">
<CFPROCPARAM type="IN" dbvarname="@ISBN" value="#Form.ISBN#"
	cfsqltype="CF_SQL_VARCHAR">
</CFSTOREDPROC>
Note: Parameter arrays cannot be used outside of a loop except as part of a conditional directive expression.

Using the loop directive’s _length and _index variables

The loop directive includes two built‑in variables that you can use for embedded if conditions. The variables are: _length and _index. The _length variable evaluates to the length of the arrays processed by the loop directive, while the _index variable evaluates to the current index of the loop directive. To ensure that the variables are only recognized as directives, and not as actual parameters to be passed into the loop, do not enclose either variable in @@s.

An example of using built‑in variables is to apply them to the import attribute of the page directive. The import attribute requires comma separation of packages. If the loop directive extends around the entire import attribute, you would only output the attribute name import= on the first iteration of the loop—this includes the closing double quote (")—and not output a comma on the last iteration of the loop. Using the built‑in variable, you can express this as follows:

<@loop (@@Import@@)@>
<@ if(_index == 0)@>import="
<@endif@>@@Import@@<@if (_index == _length-1)@>"<@else@>,
<@ endif @>
<@endloop@>