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Exception Handling In perl

Posted on 2004-10-18
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Last Modified: 2008-02-20
Is it possible to have exception handling in perl with try catch loop?  I  am using DBI and is inserting data from a csv into a database inisde a while loop. Can I use try catch loop instead of  eval {.........}; if($@){.....}   commands.  I want that if a insertion fails that the process should not stop and should continue after throwing an excpetion till the end of the CSV.  

I am trying to use the error module but it didn't work.......
use Error qw(:try);
try{
    $sql = qq{Insert into SHIMADZU_METADATA(User_id, Filename, Date_Time) values (?, ?, ?)};
    $sth = $dbh->prepare($sql) || die;
    $sth->execute($UserId, $datafile, $fileDate);
    $sth->commit();
}catch{

}
0
Comment
Question by:subirc
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9 Comments
 

Author Comment

by:subirc
ID: 12344048
Can eval statament do the same thing?

Thanks,
Subirc
0
 
LVL 20

Expert Comment

by:jmcg
ID: 12344693
Yes, the eval statement can be used. The 'try' function from that module is mostly just syntactic sugar built around 'eval'.

You haven't explained "it didn't work" in enough detail for experts to be able to give you much of an answer. Please elaborate.
0
 
LVL 18

Expert Comment

by:kandura
ID: 12345802
jmcg is quite right. Eval will do just fine. In either way I'd recommend you turn on RaiseError on the database handle, at least for the duration of the try block:
That way it dies whenever there's an error, not just on the prepare (in fact, the execute statement is a lot more dangerous).

    eval {
        local $dbh->{RaiseError} = 1;

    };

   
FYI, the Error syntax is:

    try {
        ...
    } catch Error with {
        my $Err = shift;
        ...
    };

or

    try {
        ...
    } otherwise {
        ...
    };
0
 

Author Comment

by:subirc
ID: 12347925
jmcg,

"it didn't work" means that once a particular row failed and threw an error ....the script stopped running and nothing following got transmitted..................

Subirc
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LVL 20

Expert Comment

by:jmcg
ID: 12348298
Just off the top of my head, I think you'll need to arrange to insert one row at a time. This will allow you to handle and dismiss the exception when it occurs, then continue. I don't know of a way to both have the error reported and to continue processing after the error.
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LVL 18

Accepted Solution

by:
kandura earned 20 total points
ID: 12348937
Indeed.

You need to do the prepare beforehand, and wrap each execute in an eval. Optionally you could wrap the entire db business in another eval:

    use Error qw(:try);

    eval {
        $sql = qq{Insert into SHIMADZU_METADATA(User_id, Filename, Date_Time) values (?, ?, ?)};
        local $dbh->{RaiseError} = 1;
        my $sth = $dbh->prepare($sql);

        try{
            $sth->execute($UserId, $datafile, $fileDate);
            $sth->commit();
        } catch Error with {
            my $E = shift;
            $sth->rollback;
            warn "Error committing row: $E";
        };
    } or warn "Error with insert: $@";
0
 

Author Comment

by:subirc
ID: 12349129
ya I am doing one row at a time

use strict;
use DBI qw(:sql_types);
eval{
      local $dbh->{RaiseError} = 1;      #added as per kandura's suggestion
      $sth->execute($UserId, $datafile, $fileDate);
      $sth->commit();
};
if ($@) {
    print $@
}

Here's the error.......
Can't locate object method "Commit" via package "DBI::st" (perhaps you forgot to load "DBI::st"?) ...never seen this error
0
 

Author Comment

by:subirc
ID: 12349177
Think it's a diff error..... can't able to see commit........I tried  commit()....but still failed......
0
 

Author Comment

by:subirc
ID: 12349302
got it;  it  shld be  $dbh->commit   not  $sth...................................!!!!
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