Is try-catch like error handling possible in ASP Classic

Question

What options are there in ASP Classic for error handling   For example   I m using the Mail SendMail function but when switching on the testing server it doesn t work  which is normal  I want to test if mailing is possible  if not then continue and or show a message   Any ideas

User · Answer

Some scenarios don t always allow developers to switch scripting language   My preference is definitely for JavaScript  and I have used it in new projects   However  maintaining older projects is still required and necessary  Unfortunately  these are written in VBScript   So even though this solution doesn t offer true  try catch  functionaility  the result is the same  and that s good enough for me to get the job done

User · Answer

the statement On Error Resume Next should be placed on top of what we want to validate     On Error Resume Next    Your code logic is here   Then end with statement like      If Err Number  lt  gt  0 then     Your error message goes here     End if

User · Answer

1  Add On Error Resume Next at top of the page  2  Add following code at bottom of the page  If Err Number  lt  gt  0 Then    Response Write  Err Description        Response End   End If  On Error GoTo 0

User · Answer

For anytone who has worked in ASP as well as more modern languages  the question will provoke a chuckle   In my experience using a custom error handler  set up in IIS to handle the 500 100 errors  is the best option for ASP error handling   This article describes the approach and even gives you some sample code   database table definition   http   www 15seconds com issue 020821 htm  Here is a link to Archive org s version

User · Answer

Been a while since I was in ASP land  but iirc there s a couple of ways   try catch finally can be reasonably simulated in VBS  good article here here   and there s an event called class terminate you can watch and catch exceptions globally in  Then there s the possibility of changing your scripting language

User · Answer

There are two approaches  you can code in JScript or VBScript which do have the construct or you can fudge it in your code    Using JScript you d use the following type of construct    lt script language  jscript  runat  server  gt  try        tryStatements   catch exception        catchStatements   finally       finallyStatements    lt  script gt    In your ASP code you fudge it by using on error resume next at the point you d have a try and checking err Number at the point of a catch like    lt     Turn off error Handling On Error Resume Next    Code here that you want to catch errors from    Error Handler If Err Number  lt  gt  0 Then      Error Occurred - Trap it    On Error Goto 0   Turn error handling back on for errors in your handling block      Code to cope with the error here End If On Error Goto 0   Reset error handling     gt

User · Answer

Been a while since I was in ASP land  but iirc there s a couple of ways   try catch finally can be reasonably simulated in VBS  good article here here   and there s an event called class terminate you can watch and catch exceptions globally in  Then there s the possibility of changing your scripting language

User · Answer

For anytone who has worked in ASP as well as more modern languages  the question will provoke a chuckle   In my experience using a custom error handler  set up in IIS to handle the 500 100 errors  is the best option for ASP error handling   This article describes the approach and even gives you some sample code   database table definition   http   www 15seconds com issue 020821 htm  Here is a link to Archive org s version

User · Answer

A rather nice way to handle this for missing COM classes   Dim o Set o   Nothing On Error Resume Next Set o   CreateObject  foo bar   On Error Goto 0 If o Is Nothing Then   Response Write  Oups  foo bar isn t installed on this server   Else   Response Write  Foo bar found  yay   End If

User · Answer

There are two approaches  you can code in JScript or VBScript which do have the construct or you can fudge it in your code    Using JScript you d use the following type of construct    lt script language  jscript  runat  server  gt  try        tryStatements   catch exception        catchStatements   finally       finallyStatements    lt  script gt    In your ASP code you fudge it by using on error resume next at the point you d have a try and checking err Number at the point of a catch like    lt     Turn off error Handling On Error Resume Next    Code here that you want to catch errors from    Error Handler If Err Number  lt  gt  0 Then      Error Occurred - Trap it    On Error Goto 0   Turn error handling back on for errors in your handling block      Code to cope with the error here End If On Error Goto 0   Reset error handling     gt

User · Answer

the statement On Error Resume Next should be placed on top of what we want to validate     On Error Resume Next    Your code logic is here   Then end with statement like      If Err Number  lt  gt  0 then     Your error message goes here     End if

User · Answer

There are two approaches  you can code in JScript or VBScript which do have the construct or you can fudge it in your code    Using JScript you d use the following type of construct    lt script language  jscript  runat  server  gt  try        tryStatements   catch exception        catchStatements   finally       finallyStatements    lt  script gt    In your ASP code you fudge it by using on error resume next at the point you d have a try and checking err Number at the point of a catch like    lt     Turn off error Handling On Error Resume Next    Code here that you want to catch errors from    Error Handler If Err Number  lt  gt  0 Then      Error Occurred - Trap it    On Error Goto 0   Turn error handling back on for errors in your handling block      Code to cope with the error here End If On Error Goto 0   Reset error handling     gt

User · Answer

Regarding Wolfwyrd s anwer   On Error Resume Next  in fact turns error handling off  Not on  On Error Goto 0 turns error-handling back ON because at the least  we want the machine to catch it if we didn t write it in ourselves  Off   leaving it to you to handle it   If you use On Error Resume Next  you need to be careful about how much code you include after it  remember  the phrase  If Err Number  lt   0 Then  only refers to the most previous error triggered    If your block of code after  On Error Resume Next  has several places where you might reasonably expect it to fail  then you must place  If Err number  lt   0  after each and every one of those possible failure lines  to check execution   Otherwise  after  on error resume next  means just what it says - your code can fail on as many lines as it likes and execution will continue merrily along  That s why it s a pain in the ass

User · Answer

There are two approaches  you can code in JScript or VBScript which do have the construct or you can fudge it in your code    Using JScript you d use the following type of construct    lt script language  jscript  runat  server  gt  try        tryStatements   catch exception        catchStatements   finally       finallyStatements    lt  script gt    In your ASP code you fudge it by using on error resume next at the point you d have a try and checking err Number at the point of a catch like    lt     Turn off error Handling On Error Resume Next    Code here that you want to catch errors from    Error Handler If Err Number  lt  gt  0 Then      Error Occurred - Trap it    On Error Goto 0   Turn error handling back on for errors in your handling block      Code to cope with the error here End If On Error Goto 0   Reset error handling     gt

User · Answer

1  Add On Error Resume Next at top of the page  2  Add following code at bottom of the page  If Err Number  lt  gt  0 Then    Response Write  Err Description        Response End   End If  On Error GoTo 0

User · Answer

Some scenarios don t always allow developers to switch scripting language   My preference is definitely for JavaScript  and I have used it in new projects   However  maintaining older projects is still required and necessary  Unfortunately  these are written in VBScript   So even though this solution doesn t offer true  try catch  functionaility  the result is the same  and that s good enough for me to get the job done

User · Answer

A rather nice way to handle this for missing COM classes   Dim o Set o   Nothing On Error Resume Next Set o   CreateObject  foo bar   On Error Goto 0 If o Is Nothing Then   Response Write  Oups  foo bar isn t installed on this server   Else   Response Write  Foo bar found  yay   End If

User · Answer

Been a while since I was in ASP land  but iirc there s a couple of ways   try catch finally can be reasonably simulated in VBS  good article here here   and there s an event called class terminate you can watch and catch exceptions globally in  Then there s the possibility of changing your scripting language

User · Answer

Been a while since I was in ASP land  but iirc there s a couple of ways   try catch finally can be reasonably simulated in VBS  good article here here   and there s an event called class terminate you can watch and catch exceptions globally in  Then there s the possibility of changing your scripting language

User · Answer

Regarding Wolfwyrd s anwer   On Error Resume Next  in fact turns error handling off  Not on  On Error Goto 0 turns error-handling back ON because at the least  we want the machine to catch it if we didn t write it in ourselves  Off   leaving it to you to handle it   If you use On Error Resume Next  you need to be careful about how much code you include after it  remember  the phrase  If Err Number  lt   0 Then  only refers to the most previous error triggered    If your block of code after  On Error Resume Next  has several places where you might reasonably expect it to fail  then you must place  If Err number  lt   0  after each and every one of those possible failure lines  to check execution   Otherwise  after  on error resume next  means just what it says - your code can fail on as many lines as it likes and execution will continue merrily along  That s why it s a pain in the ass

[error-handling] Is try-catch like error handling possible in ASP Classic?

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