How do you call a method from a variable in ASP Classic? - asp-classic

For example, how can I run me.test below?
myvar = 'test'
me.myvar
ASP looks for the method "myvar" and doesn't find it. In PHP I could simply say $me->$myvar but ASP's syntax doesn't distinguish between variables and methods. Suggestions?
Closely related to this, is there a method_exists function in ASP Classic?
Thanks in advance!
EDIT: I'm writing a validation class and would like to call a list of methods via a pipe delimited string.
So for example, to validate a name field, I'd call:
validate("required|min_length(3)|max_length(100)|alphanumeric")
I like the idea of having a single line that shows all the ways a given field is being validated. And each pipe delimited section of the string is the name of a method.
If you have suggestions for a better setup, I'm all ears!

You can achieve this in VBScript by using the GetRef function:-
Function Test(val)
Test = val & " has been tested"
End Function
Dim myvar : myvar = "Test"
Dim x : Set x = GetRef(myvar)
Response.Write x("Thing")
Will send "Thing has been tested" to the client.
So here is your validate requirement using GetRef:-
validate("Hello World", "min_length(3)|max_length(10)|alphanumeric")
Function required(val)
required = val <> Empty
End Function
Function min_length(val, params)
min_length = Len(val) >= CInt(params(0))
End Function
Function max_length(val, params)
max_length = Len(val) <= CInt(params(0))
End Function
Function alphanumeric(val)
Dim rgx : Set rgx = New RegExp
rgx.Pattern = "^[A-Za-z0-9]+$"
alphanumeric = rgx.Test(val)
End Function
Function validate(val, criterion)
Dim arrCriterion : arrCriterion = Split(criterion, "|")
Dim criteria
validate = True
For Each criteria in arrCriterion
Dim paramListPos : paramListPos = InStr(criteria, "(")
If paramListPos = 0 Then
validate = GetRef(criteria)(val)
Else
Dim paramList
paramList = Split(Mid(criteria, paramListPos + 1, Len(criteria) - paramListPos - 1), ",")
criteria = Left(criteria, paramListPos - 1)
validate = GetRef(criteria)(val, paramList)
End If
If Not validate Then Exit For
Next
End Function
Having provided this I have to say though that if you are familiar with PHP then JScript would be a better choice on the server. In Javascript you can call a method like this:-
function test(val) { return val + " has been tested"; )
var myvar = "test"
Response.Write(this[myvar]("Thing"))

If you are talking about VBScript, it doesn't have that kind of functionality. (at least not to my knowledge) I might attempt it like this :
Select myvar
case "test":
test
case "anotherSub":
anotherSub
else
defaultSub
end select
It's been a while since I wrote VBScript (thank god), so I'm not sure how good my syntax is.
EDIT-Another strategy
Personally, I would do the above, for security reasons. But if you absolutely do not like it, then you may want to try using different languages on your page. I have in the past used both Javascript AND VBScript on my Classic ASP pages (both server side), and was able to call functions declared in the other language from my current language. This came in especially handy when I wanted to do something with Regular Expressions, but was in VBScript.
You can try something like
<script language="vbscript" runat="server">
MyJavascriptEval myvar
</script>
<script language="javascript" runat="server">
function MyJavascriptEval( myExpression)
{
eval(myExpression);
}
/* OR
function MyJavascriptEval( myExpression)
{
var f = new Function(myExpression);
f();
}
*/
</script>
I didn't test this in a classic ASP page, but I think it's close enough that it will work with minor tweaks.

Use the "Execute" statement in ASP/VBScript.
Execute "Response.Write ""hello world"""

PHP's ability to dynamically call or create functions are hacks that lead to poor programming practices. You need to explain what you're trying to accomplish (not how) and learn the correct way to code.
Just because you can do something, doesn't make it right or a good idea.

ASP does not support late binding in this manner. What are you trying to do, in a larger sense? Explain that, and someone can show you how to accomplish it in asp.

Additionally, you might consider "objectifying" the validation functionality. Making classes is possible (though not widely used) in VB Script.
<%
Class User
' declare private class variable
Private m_userName
' declare the property
Public Property Get UserName
UserName = m_userName
End Property
Public Property Let UserName (strUserName)
m_userName = strUserName
End Property
' declare and define the method
Sub DisplayUserName
Response.Write UserName
End Sub
End Class
%>

Related

Problems with If Statement (ASP.NET)

Dim custEmail As String
Dim inputEmail As String
custEmail = dt.Rows(0).Item("email")
inputEmail = email_add.Text
if (custEmail.toString() == inputEmail.toString() ){
label1.Text = custEmail
}
End If
This code is giving an error: Compiler Error Message: BC30201: Expression expected.
I just basically want to check if two values are equal but its saying something about expression expected although i've given the expression to evaluate.
The above is a mix of vb.net and c# syntax. You can use either in .net with success but not both at the same time. Get rid of the { and } to stick with vb.
Looks like you are mixing C# and VB.Net. Assuming you are using VB.Net
Replace the '{' with Begin IF and remove the '}'.

Where do DAC objects live (in Classic ASP)?

I have taken over a departing programmer's Classic ASP object, and I'm trying to debug some DAC code. The trouble is I don't really understand what DAC is or how it works -- and I can't find were the DAC code "lives".
Here's the individual line of code:
set runObj = server.CreateObject("DAC.clsDb_container")
We use SQL Server, and I looked in Enterprise Manager under Stored Procedures and User-Defined functions, but I don't see anything named clsDB_container.
Any suggestions where I can find the code for this DAC object?
The full code in context:
FUNCTION getNewGUID
Dim runCON, runObj, runCMD
DebugWrite( "<BEGIN> iRoutines.asp|getNewGUID (a) GUID=" & GUID & " dealernum=" & dealernum )
set runObj = server.CreateObject("DAC.clsDb_container")
if not runObj.run_query("EXEC sproc_createGUID") then
traperror(runObj.DB_ErrStr)
else
GUID = replace(runObj.get_by_ordinal(0),"-","")
dealernum_len = trim(cstr(len(dealernum)))
set runObj = nothing
end if
getNewGUID = dealernum_len & dealernum & GUID
DebugWrite( "<END> iRoutines.asp|getNewGUID (b) getNewGUID=" & getNewGUID & " dealernum=" & dealernum )
END FUNCTION
This looks like a custom COM object that was written as a data access layer for the site.
The name of the object would be DAC.clsDb_container and lives in a DLL somewhere on the web server.
It is not standard - you will need to look for (I am guessing here) the VB6 or Delphi code that created it if you want to be enlightened further.
if all you need is a GUID then you could do this
<%
Function createGuid()
Set TypeLib = Server.CreateObject("Scriptlet.TypeLib")
dim tg : tg = TypeLib.Guid
createGuid = left(tg, len(tg)-2)
Set TypeLib = Nothing
End Function
%>

Accessing VB6 Collection Item from VBScript embedded in HTML

i'm learning by practice. I was given an OCX file which according to who gave it to me was created using VB6 and I have the task of creating a user interface for it to test all the functionality that is described in a poorly written documentation file. On top of that I am not well-versed in VBScript but I've managed to dodge a few bullets while learning.
I have a method which returns a Collection and when I try to access it from VBScript I am only able to query the Count but when I try to do job.Item(i) or job(i) I get an error stating it doesn't have that property or method.
Can someone point me in the right direction to be able to traverse the contents of this collection?
I had to do it from JavaScript but since some things weren't that easy I decided that perhaps VBScript would help me bridge the gaps where JavaScript didn't cut it. I can access all properties from the ActiveXObject from JavaScript, but the methods which return other VB objects are a little more obscure to me. I've tried aJob.Item(iCount), aJob.Items(iCount) and aJob(iCount).
My code is:
For iCount = 1 To aJobs.Count
MsgBox("Num " & iCount)
MsgBox(aJobs.Item(iCount))
Next
Thanks.
People often create specialized and/or strongly typed collection classes in VB6. They don't always do it correctly though, and they sometimes create "partial" collection implementations that have no Item() method (or fail to mark it as the default member of the class). They might even have a similar method or property but name it something entirely different.
It is rarer to return a raw Collection object, but it can be done and if it is you shouldn't have the problems you have indicated from VBScript.
I just created a DLL project named "HallLib" with three classes: Hallway, DoorKnobs, and DoorKnob. The DoorKnobs class is a collection of DoorKnob objects. The Hallway class has a DoorKnobs object that it initializes with a random set of DoorKnob objects with randomly set properties. Hallway.DoorKnobs() returns the DoorKnobs collection object as its result.
It works fine in this script:
Option Explicit
Dim Hallway, DoorKnobs, DoorKnob
Set Hallway = CreateObject("HallLib.Hallway")
Set DoorKnobs = Hallway.DoorKnobs()
MsgBox "DoorKnobs.Count = " & CStr(DoorKnobs.Count)
For Each DoorKnob In DoorKnobs
MsgBox "DoorKnob.Material = " & CStr(DoorKnob.Material) & vbNewLine _
& "DoorKnob.Color = " & CStr(DoorKnob.Color)
Next
Update:
This script produces identical results:
Option Explicit
Dim Hallway, DoorKnobs, KnobIndex
Set Hallway = CreateObject("HallLib.Hallway")
Set DoorKnobs = Hallway.DoorKnobs()
MsgBox "DoorKnobs.Count = " & CStr(DoorKnobs.Count)
For KnobIndex = 1 To DoorKnobs.Count
With DoorKnobs.Item(KnobIndex)
MsgBox "DoorKnob.Material = " & CStr(.Material) & vbNewLine _
& "DoorKnob.Color = " & CStr(.Color)
End With
Next
As does:
Option Explicit
Dim Hallway, DoorKnobs, KnobIndex
Set Hallway = CreateObject("HallLib.Hallway")
Set DoorKnobs = Hallway.DoorKnobs()
MsgBox "DoorKnobs.Count = " & CStr(DoorKnobs.Count)
For KnobIndex = 1 To DoorKnobs.Count
With DoorKnobs(KnobIndex)
MsgBox "DoorKnob.Material = " & CStr(.Material) & vbNewLine _
& "DoorKnob.Color = " & CStr(.Color)
End With
Next
So I suspect you'll need to use some type library browser like OLEView to look at your OCX to see what classes and members it actually exposes.

Why is this looping infinitely?

So I just got my site kicked off the server today and I think this function is the culprit. Can anyone tell me what the problem is? I can't seem to figure it out:
Public Function CleanText(ByVal str As String) As String
'removes HTML tags and other characters that title tags and descriptions don't like
If Not String.IsNullOrEmpty(str) Then
'mini db of extended tags to get rid of
Dim indexChars() As String = {"<a", "<img", "<input type=""hidden"" name=""tax""", "<input type=""hidden"" name=""handling""", "<span", "<p", "<ul", "<div", "<embed", "<object", "<param"}
For i As Integer = 0 To indexChars.GetUpperBound(0) 'loop through indexchars array
Dim indexOfInput As Integer = 0
Do 'get rid of links
indexOfInput = str.IndexOf(indexChars(i)) 'find instance of indexChar
If indexOfInput <> -1 Then
Dim indexNextLeftBracket As Integer = str.IndexOf("<", indexOfInput) + 1
Dim indexRightBracket As Integer = str.IndexOf(">", indexOfInput) + 1
'check to make sure a right bracket hasn't been left off a tag
If indexNextLeftBracket > indexRightBracket Then 'normal case
str = str.Remove(indexOfInput, indexRightBracket - indexOfInput)
Else
'add the right bracket right before the next left bracket, just remove everything
'in the bad tag
str = str.Insert(indexNextLeftBracket - 1, ">")
indexRightBracket = str.IndexOf(">", indexOfInput) + 1
str = str.Remove(indexOfInput, indexRightBracket - indexOfInput)
End If
End If
Loop Until indexOfInput = -1
Next
End If
Return str
End Function
Wouldn't something like this be simpler? (OK, I know it's not identical to posted code):
public string StripHTMLTags(string text)
{
return Regex.Replace(text, #"<(.|\n)*?>", string.Empty);
}
(Conversion to VB.NET should be trivial!)
Note: if you are running this often, there are two performance improvements you can make to the Regex.
One is to use a pre-compiled expression which requires re-writing slightly.
The second is to use a non-capturing form of the regular expression; .NET regular expressions implement the (?:) syntax, which allows for grouping to be done without incurring the performance penalty of captured text being remembered as a backreference. Using this syntax, the above regular expression could be changed to:
#"<(?:.|\n)*?>"
This line is also wrong:
Dim indexNextLeftBracket As Integer = str.IndexOf("<", indexOfInput) + 1
It's guaranteed to always set indexNextLeftBracket equal to indexOfInput, because at this point the character at the position referred to by indexOfInput is already always a '<'. Do this instead:
Dim indexNextLeftBracket As Integer = str.IndexOf("<", indexOfInput+1) + 1
And also add a clause to the if statement to make sure your string is long enough for that expression.
Finally, as others have said this code will be a beast to maintain, if you can get it working at all. Best to look for another solution, like a regex or even just replacing all '<' with <.
In addition to other good answers, you might read up a little on loop invariants a little bit. The pulling out and putting back stuff to the string you check to terminate your loop should set off all manner of alarm bells. :)
Just a guess, but is this like the culprit?
indexOfInput = str.IndexOf(indexChars(i)) 'find instance of indexChar
Per the Microsoft docs, Return Value -
The index position of value if that string is found, or -1 if it is not. If value is Empty, the return value is 0.
So perhaps indexOfInput is being set to 0?
What happens if your code tries to clean the string <a?
As I read it, it finds the indexChar at position 0, but then indexNextLeftBracket and indexRightBracket both equal 0, you fall into the else condition, and then you insert a ">" at position -1, which will presumably insert at the beginning, giving you the string ><a. The new indexRightBracket then becomes 0, so you delete from position 0 for 0 characters, leaving you with ><a. Then the code finds the <a in the code again, and you're off to the races with an infinite memory-consuming loop.
Even if I'm wrong, you need to get yourself some unit tests to reassure yourself that these edge cases work properly. That should also help you find the actual looping code if I'm off-base.
Generally speaking though, even if you fix this particular bug, it's never going to be very robust. Parsing HTML is hard, and HTML blacklists are always going to have holes. For instance, if I really want to get a <input type="hidden" name="tax" tag in, I'll just write it as <input name="tax" type="hidden" and your code will ignore it. Your better bet is to get an actual HTML parser involved, and to only allow the (very small) subset of tags that you actually want. Or even better, use some other form of markup, and strip all HTML tags (again using a real HTML parser of some description).
I'd have to run it through a real compiler but the mindpiler tells me that the str = str.Remove(indexOfInput, indexRightBracket - indexOfInput) line is re-generating an invalid tag such that when you loop through again it finds the same mistake "fixes" it, tries again, finds the mistake "fixes" it, etc.
FWIW heres a snippet of code that removes unwanted HTML tags from a string (It's in C# but the concept translates)
public static string RemoveTags( string html, params string[] allowList )
{
if( html == null ) return null;
Regex regex = new Regex( #"(?<Tag><(?<TagName>[a-z/]+)\S*?[^<]*?>)",
RegexOptions.Compiled |
RegexOptions.IgnoreCase |
RegexOptions.Multiline );
return regex.Replace(
html,
new MatchEvaluator(
new TagMatchEvaluator( allowList ).Replace ) );
}
MatchEvaluator class
private class TagMatchEvaluator
{
private readonly ArrayList _allowed = null;
public TagMatchEvaluator( string[] allowList )
{
_allowed = new ArrayList( allowList );
}
public string Replace( Match match )
{
if( _allowed.Contains( match.Groups[ "TagName" ].Value ) )
return match.Value;
return "";
}
}
That doesn't seem to work for a simplistic <a<a<a case, or even <a>Test</a>. Did you test this at all?
Personally, I hate string parsing like this - so I'm not going to even try figuring out where your error is. It'd require a debugger, and more headache than I'm willing to put in.

How do I traverse a collection in classic ASP?

I want to be able to do:
For Each thing In things
End For
CLASSIC ASP - NOT .NET!
Something like this?
dim cars(2),x
cars(0)="Volvo"
cars(1)="Saab"
cars(2)="BMW"
For Each x in cars
response.write(x & "<br />")
Next
See www.w3schools.com.
If you want to associate keys and values use a dictionary object instead:
Dim objDictionary
Set objDictionary = CreateObject("Scripting.Dictionary")
objDictionary.Add "Name", "Scott"
objDictionary.Add "Age", "20"
if objDictionary.Exists("Name") then
' Do something
else
' Do something else
end if
Whatever your [things] are need to be written outside of VBScript.
In VB6, you can write a Custom Collection class, then you'll need to compile to an ActiveX DLL and register it on your webserver to access it.
The closest you are going to get is using a Dictionary (as mentioned by Pacifika)
Dim objDictionary
Set objDictionary = CreateObject("Scripting.Dictionary")
objDictionary.CompareMode = vbTextCompare 'makes the keys case insensitive'
objDictionary.Add "Name", "Scott"
objDictionary.Add "Age", "20"
But I loop through my dictionaries like a collection
For Each Entry In objDictionary
Response.write objDictionary(Entry) & "<br />"
Next
You can loop through the entire dictionary this way writing out the values which would look like this:
Scott
20
You can also do this
For Each Entry In objDictionary
Response.write Entry & ": " & objDictionary(Entry) & "<br />"
Next
Which would produce
Name: Scott
Age: 20
One approach I've used before is to use a property of the collection that returns an array, which can be iterated over.
Class MyCollection
Public Property Get Items
Items = ReturnItemsAsAnArray()
End Property
...
End Class
Iterate like:
Set things = New MyCollection
For Each thing in things.Items
...
Next
As Brett said, its better to use a vb component to create collections. Dictionary objects are not very commonly used in ASP unless for specific need based applications.
Be VERY carefully on using VB Script Dictionary Object!
Just discover this "autovivication" thing, native on this object: http://en.wikipedia.org/wiki/Autovivification
So, when you need to compare values, NEVER use a boolen comparison like:
If objDic.Item("varName") <> "" Then...
This will automatically add the key "varName" to the dictionary (if it doesn't exist, with an empty value) , in order to carry on evaluating the boolean expression.
If needed, use instead If objDic.Exists("varName").
Just spend a few days knocking walls, with this Microsoft "feature"...
vbscript-dictionary-object-creating-a-key-which-never-existed-but-present-in-another-object

Resources