NaviServer - programmable web server

[ Main Table Of Contents | Table Of Contents | Keyword Index ]

# ns_adp_register(n) 4.99.8 naviserver "NaviServer Built-in Commands"

## Name

ns_adp_register - Creating custom ADP tags

## Table Of Contents

## Synopsis

- ns_adp_registeradp tag ?endtag? adpstring
- ns_adp_registerproc tag ?endtag? proc
- ns_adp_registerscript tag ?endtag? script

## Description

These commands enable definition of HTML tags within an ADP file which are expanded and evaluated by the server before returning output to the client. Tags are defined as eitehr a single tag with options, e.g., <mytag a=b c=d> or as an opening/closing tag pair, e.g., <mytag> text </mytag> . This approach is an alternative to direct calls via the <% script %> syntax as described in the ns_adp man page.

## COMMANDS

ns_adp_registeradp tag ?endtag? adpstring

  This command registers an ADP code fragment to be invoked when the specified tag is encountered while parsing an ADP. The tag argument specifies the tag that will trigger invocation of the ADP fragment, which is specified by the adpstring argument.

  If the endtag argument is specified, then the ADP fragment will be invoked with two arguments: The first will be the enclosed content, and the second will be the name of an ns_set with any attributes specified in the tag. If no endtag argument is specified, the ADP fragment will only be passed the name of the ns_set. The arguments may be retrieved using ns_adp_bindargs or ns_adp_argc and ns_adp_argv .

  When the ADP fragment is invoked, its result is inserted in the output instead of the tag (or, if the endtag was specified, in place of the tag, end tag, and the enclosed content).

  Note: Care must be taken when using this function from inside an ADP, because the adpstring is likely to contain script delimiters ( <% ... %> ) which will prematurely terminate script fragments. It is probably easier to restrict use of this function to .tcl files.

         ns_adp_registeradp example example.adp

         ns_adp_registeradp printdate {
              The current date is: <% ns_adp_puts [ns_httptime [ns_time]] %>
         }

  Once defined, typically in a startup script, you could simple include <example> or <printdate> in adp pages.

ns_adp_registerproc tag ?endtag? proc

  This command registers a Tcl procedure to be evaluated when the given tag is encountered. The tag argument specifies the tag that will trigger a call to the procedure specified by the proc argument.

  The procedure will be called with a variable number of arguments, one for each of the attributes provided in the tag. If the endtag argument is specified, the procedure will also receive a final argument with the contents of the text enclosed between the tags. No evaluation of the content will be performed, it will be passed as a single text block.

  When the procedure is invoked, its result is inserted in the output instead of the tag (or, if the endtag was specified, in place of the tag, end tag, and the enclosed content).

ns_adp_registerscript tag ?endtag? script

  This command registers a Tcl script to be evaluated when the given tag is encountered. The tag argument specifies the tag that will trigger evaluation of the script specified by the script argument.

  If the endtag argument is specified, then the script will be modified with two arguments appended: The first will be the enclosed content, and the second will be the name of an ns_set with any attributes specified in the tag. If no endtag argument is specified, the script will be modified with just the name of the ns_set appended.

  When the script is evaluated, its result is inserted in the output instead of the tag (or, if the endtag was specified, in place of the tag, end tag, and the enclosed content).

  The following is a simple way of handling conditional content in ADPs:

      proc remember {input tagset} {
         global _adp_memory
         set tagname [ns_set iget $tagset name]
         if {[string match "" $tagname]} {
           set _adp_memory($tagname) $input
           return ""
         } else {
           return $input
         }
      }
      proc recall {name} {
         global _adp_memory
         if {[info exists _adp_memory($name)]} {
           set parsecommand [list ns_adp_parse -string]
           lappend parsecommand $_adp_memory($name)
           ns_puts -nonewline [uplevel $parsecommand]
         } else {
           ns_log Error "[ns_adp_argv 0]: Unable to recall"
         }
      }

  If the preceding Tcl has been executed (perhaps during server startup), then the following ADP fragment displays the results of a database query in a table, or shows "No rows in result." if there are no rows:

      <%
        set rows {}
        set db [ns_db gethandle]
        ns_db exec "select somecolumn from sometable"
        set row [ns_db bindargs $db]
        while {[ns_db getrow $db $row]}  {
            lappend rows [ns_set get $row "somecolumn"]
        }
        ns_db releasehandle $db
      %>
      <remember name="has-rows_header"> <table> </remember>
      <remember name="hasrows_rows"> <tr><td><%=$column%></td></tr> </remember>
      <remember name="hasrows_footer"> </table> </remember>
      No rows in result.
      <remember name="norows">
      <%
      if {[llength $rows]  >  0}  {
        recall  "hasrows_header"
        foreach row $rows {
          set column $row
          recall "hasrows_rows"
        }
        recall "hasrows_footer"
      } else {
        recall "norows"
      }
      %>

## See Also

ns_adp, ns_adp_eval, ns_adp_include, ns_adp_safeeval