ad_page_variables

ad_page_variables   variable_specs

    Current syntax:
    
    ad_page_variables {var_spec1 [varspec2] ... }
    
    This proc handles translating form inputs into Tcl variables, and checking
    to see that the correct set of inputs was supplied.  Note that this is mostly a
    check on the proper programming of a set of pages.
    
    Here are the recognized var_specs:
    
    variable                            ; means it's required
    {variable default-value}
    Optional, with default value.  If the value is supplied but is null, and the
    default-value is present, that value is used.
    {variable -multiple-list}
    The value of the Tcl variable will be a list containing all of the
                    values (in order) supplied for that form variable.  Particularly useful
    for collecting checkboxes or select multiples.
    Note that if required or optional variables are specified more than once, the
    first (leftmost) value is used, and the rest are ignored.
    {variable -array}
    This syntax supports the idiom of supplying multiple form variables of the
    same name but ending with a "_[0-9]", e.g., foo_1, foo_2.... Each value will be
    stored in the array variable variable with the index being whatever follows the
    underscore.
    
    There is an optional third element in the var_spec.  If it is "QQ", "qq", or
    some variant, a variable named "QQvariable" will be created and given the
    same value, but with single quotes escaped suitable for handing to SQL.
    
    Other elements of the var_spec are ignored, so a documentation string
    describing the variable can be supplied.
    
    Note that the default value form will become the value form in a "set"
    
    Note that the default values are filled in from left to right, and can depend on
    values of variables to their left:
    ad_page_variables {
	file
	{start 0}
	{end {[expr $start + 20]}}
    }
    

Source code:

    set exception_list [list]
    set form [ns_getform]
    if { $form != "" } {
	set form_size [ns_set size $form]
	set form_counter_i 0
	
	# first pass -- go through all the variables supplied in the form
	while {$form_counter_i<$form_size} {
	    set variable [ns_set key $form $form_counter_i]
	    set value [ns_set value $form $form_counter_i]
	    check_for_form_variable_naughtiness $variable $value
	    set found "not"
	    # find the matching variable spec, if any
	    foreach variable_spec $variable_specs {
		if { [llength $variable_spec] >= 2 } {
		    switch -- [lindex $variable_spec 1] {
			-multiple-list {
			    if { [lindex $variable_spec 0] == $variable } {
				# variable gets a list of all the values
				upvar 1 $variable var
				lappend var $value
				set found "done"
				break
			    }
			}
			-array {
			    set varname [lindex $variable_spec 0]
			    set pattern "($varname)_(.+)"
			    if { [regexp $pattern $variable match array index] } {
				if { ![empty_string_p $array] } {
				    upvar 1 $array arr
				    set arr($index) [ns_set value $form $form_counter_i]
				}
				set found "done"
				break
			    }
			}
			default {
			    if { [lindex $variable_spec 0] == $variable } {
				set found "set"
				break
			    }
			}
		    }
		} elseif { $variable_spec == $variable } {
		    set found "set"
		    break
		}
	    }
	    if { $found == "set" } {
		upvar 1 $variable var
		if { ![info exists var] } {
		    # take the leftmost value, if there are multiple ones
		    set var [ns_set value $form $form_counter_i]
		}
	    }
	    incr form_counter_i
	}
    }
    
    # now make a pass over each variable spec, making sure everything required is there
    # and doing defaulting for unsupplied things that aren't required
    foreach variable_spec $variable_specs {
	set variable [lindex $variable_spec 0]
	upvar 1 $variable var
	
	if { [llength $variable_spec] >= 2 } {
	    if { ![info exists var] } {
		set default_value_or_flag [lindex $variable_spec 1]
		
		switch -- $default_value_or_flag {
		    -array {
			# don't set anything
		    }
		    -multiple-list {
			set var [list]
		    }
		    default {
			# Needs to be set.
			uplevel [list eval set $variable "\[subst [list $default_value_or_flag]\] "]
			# This used to be:
			#
			#   uplevel [list eval [list set $variable "$default_value_or_flag"]]
			#
			# But it wasn't properly performing substitutions.
		    }
		}
	    }
			  
	    		
	} else {
	    if { ![info exists var] } {
		lappend exception_list "\"$variable\" required but not supplied"
	    }
	}
	
	# modified by rhs@mit.edu on 1/31/2000
	# to QQ everything by default (but not arrays)
	if {[info exists var] && ![array exists var]} {
	    upvar QQ$variable QQvar
	    set QQvar [DoubleApos $var]
	}
	
    }
    
    set n_exceptions [llength $exception_list]
    # this is an error in the HTML form
    if { $n_exceptions == 1 } {
	ns_returnerror 500 [lindex $exception_list 0]
	    return -code return
    } elseif { $n_exceptions > 1 } {
	ns_returnerror 500 "<li>[join $exception_list "\n<li>"]\n"
	return -code return
    }