ns_adp_register - Creating custom ADP tags
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 either 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.
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 ADP string 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.
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).
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} {
set tagname [ns_set iget $tagset name]
if {[string match "" $tagname]} {
set ::_adp_memory($tagname) $input
return ""
} else {
return $input
}
}
proc recall {name} {
if {[info exists ::_adp_memory($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"
}
%>