CGI: VBScript CGI Property Class 1
VBScript and JavaScript CGI
VBScript CGI Property Class 1
This page revisits the Get CGI variables function.
The function provides a method to retrieve variables that were sent using either Post or Get. It is specific to Get and Post variables, obtaining other CGI variables requires another function.
This page covers a class that encapsulates both functions and to provide a unified interface. This CGI get property class allows any CGI variable to be obtained.
Class interface
A class’s interface allows you to interact with an object (component) created from the class blueprint. When designing an interface keep it simple; makes the class design quicker by reducing number of properties and methods to be designed and tested.
The CGI get property class is an example of this minimalist approach; requiring only a single method to retrieve a named variables value. During a page’s design you probably will want to view all variables passed to it. This is easy to implement, in terms of code and effort requires little overhead. The final interface consists of two methods:
- object_name.getvar("variable name") - get value of named variable
- object_name.list - display a list of all variables and values
CGI get property class
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Complete class is shown on the right. With the exception of section Save process cgi variables the code has been covered on previous pages. Constructor:
Environment variable name = Environment variable value A regex extracts the name and value parts ignoring the equals and stores them into the dictionary as keys and items respectively. Finally subroutine extracts name and value pairs from the encoded data sent to with the page. This could be the result of either a Get or Post from a form. Equally may have been a Get posted from a page link.
=== Save Class === Next section provides an example of using the class it assumes the class has been saved in a separate file common_functions.vbs
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Class cgi_get_var_class
Private my_hash 'Local storage
'--Constructor
Private Sub Class_Initialize() 'Set inital
Set my_hash = CreateObject("Scripting.Dictionary")'Create associative array
save_cgi_variables
End Sub
'-- Load cgi variables into local storage
Sub save_cgi_variables
Dim wshShell,wshUserEnv,strItem,objRegEx,colMatches,pair1,pair2
Dim method,data_string,variable_array,cgi_variable,decoded_value,i
Dim key_array,strKey
'---Save process cgi variables
Set wshShell = CreateObject( "WScript.Shell" ) 'Create shell object
Set wshUserEnv = wshShell.Environment( "Process" ) 'Read process collection
Set objRegEx = New RegExp 'Create new reg obj
objRegEx.Pattern = "^(.+?)=(.+)" 'Pattern to search for
'(.+?) non-greedy (.+) greedy
For Each strItem In wshUserEnv 'Scan returned collection
'--Perform regex
Set colMatches = objRegEx.Execute(strItem) 'Return Matched objects
If colMatches.Count < 0 Then 'Match found
pair1 = colMatches(0).SubMatches(0) 'Extract first capturing group
pair2 = colMatches(0).SubMatches(1) 'Extract second capturing group
my_hash.Add pair1,pair2 'Save locally
'WScript.Echo pair1 & "====" & pair2 & "<br />"'Test code
End If
Next 'get next item
'---Save Post or Get variables
method = wshUserEnv("REQUEST_METHOD") 'Get method
data_string = wshUserEnv("QUERY_STRING") 'Get query string
If method="POST" Then 'If post data read stdin
data_string = WScript.Stdin.ReadAll 'Get post data
End IF
Set wshShell = Nothing 'clean-up
Set wshUserEnv = Nothing
variable_array = split (data_string, "&") 'split data save to array
'--Save internally to my_hash - scripting dictionary
for i = 0 to ubound(variable_array) 'Scan array
cgi_variable = split (variable_array(i), "=") 'Split variable-value pairs
decoded_value1 = replace(cgi_variable(0), "+", " ")'Replace special character
decoded_value1 = unescape(decoded_value1) 'Decode encoded value
decoded_value2 = replace(cgi_variable(1), "+", " ")'Replace special character
decoded_value2 = unescape(decoded_value2) 'Decode encoded value
my_hash.add decoded_value1, decoded_value2 'Add to dictionary
next 'Get next pair
End Sub
'--Get named variable from my_hash
Public Function getvar(key)
getvar = my_hash.Item(key) 'return item
End Function
'--List all data in my_hash used for testing
Public Sub list()
Dim key_array, strKey
key_array = my_hash.Keys 'Get all Keys
For Each strKey in key_array 'Scan array
Wscript.Echo strKey & " = " & my_hash.Item(strKey) & "<br />"
Next
End Sub
'--Clean-up this class
Private Sub Class_Terminate()
'Cleaning up code.
Set my_hash = Nothing 'clean-up
End Sub
End Class
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Test script 15 - Using the CGI get property class
The following provides a working example showing how to use the CGI get property class and how to include an external file containing this class.
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Script format
First a new object named cgi is created using the New directive and the class template cgi_get_var_class.
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'!c:/windows/system32/cscript //nologo
<job>
'--1) Include any external files
<script language="VBScript" src="common_functions.vbs"/>
'--2) Main script ---
<script language="VBScript">
Option Explicit ' Force explicit variable declaration.
Wscript.Echo "Content-type: text/html"&vbLF&vbLF
Wscript.Echo "<title>Test 15</title>"
'--3) Start page code ---
Dim cgi
set cgi = New cgi_get_var_class 'Create new object
'cgi.list '** Test code **
'Display form variables
Wscript.Echo "Hidden var = " & cgi.getvar("Hidden") & "<br />"
Wscript.Echo "Text box var = " & cgi.getvar("text box")& "<br />"
Wscript.Echo "Link test var = " & cgi.getvar("alink")
Wscript.Echo "<br /><br />"
'--Form method post
WScript.Echo "<form method=""POST"" action=""class_cgi_2.wsf"" >"
WScript.Echo " <input type=""text"" name=""text box"" value=""Post Test"">"
WScript.Echo " <input type=""hidden"" name=""Hidden"" value=""Test 15"">"
WScript.Echo " <input type=""submit"" value=""Post"">"
WScript.Echo "</form>"
'--Form method get
WScript.Echo "<form method=""GET"" action=""class_cgi_2.wsf"" >"
WScript.Echo " <input type=""text"" name=""text box"" value=""Get Test"">"
WScript.Echo " <input type=""hidden"" name=""Hidden"" value=""Test 15"">"
WScript.Echo " <input type=""submit"" value=""Get"">"
WScript.Echo "</form>"
WScript.Echo "<a href=""class_cgi_2.wsf?alink=my page 2"">Test Link</a>"
</script>
</job>
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Enter data into a form’s text box and click corresponding test button. Note hidden and text box variable values are displayed but not the Test Link data. Click the Test Link, only its variable data is displayed and not the form data variables these are cleared.
Summary
The CGI get property class allows you to easily obtain any CGI variable however currently it is lacking cookie variables these are covered next.
Where to next
Next page covers expanding the CGI get property class to include cookie variables.