Category: | Web Stuff |
Author/Contact Info | ovid@easystreet.com |
Description: | If our Web server receives an image request and the image is not found, the Web server calls a cgi script to serve the image. The script analyzes the request and serves the appropriate image from MS SQL 7.0 Server.
I have posted this code to show an extensible method of serving images in the event that any monks are called upon to write a similar script. This can easily be modified to allow calls directly from a CGI script in the following format: <img src="/cgi-bin/images.cgi?image=category1234" height=40 width=40 alt="some text"> Then, you'd add the following to your code: Then, substitute the following line: With this line:
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#!C:/perl/bin/perl.exe -wT use strict; use DBI qw(:sql_types); # This program works as follows: # In a Web document, if an image is not found, the server calls this s +cript # The script checks the $ENV{'QUERY_STRING'} for the image name. # If the image name is not in the form /([a-zA-z])(\d+)\.($types)/, # the script exits and a broken image link will result, letting the de +veloper # know that there's a typo in the image format. # # If the image is in the proper form, the script queries the appropria +te # database to see if the image is there. If it is, the image is serve +d. # # If it is not, the appropriate noImage path is pulled from %catData # and this image is served instead, letting the developer know that th +e # image format is correct, but an image probably needs to be added to # the database. my ($imageType, $imageID, $types, $extension, $table, $field, $noImage +, $image, %mimeType, %catData); # Keys should mirror extensions and values should be the proper MIME t +ype # Currently, we only use gifs and jpegs. %mimeType = (jpg => 'jpeg', gif => 'gif'); # This creates an extension alternation to be used in a regex $types = join '|', keys %mimeType; # The catData hash fields are as follows: # # primary key -- This corresponds to $imageType # database -- Database image is in # table -- Table in database # field -- field in table where image is stored # noImage -- Path to image to display if no image found in databas +e # mimetype -- If an explicit mime type is not listed, this represen +ts # the fieldname in table that the mime type is stored i +n # This probably will not be used, but is included on th +e # off chance that this is necessary in the future. # Thus, if in our UFMCatalog database, in table _5, we have an image w +ith # an ID of 4392, a proper request for it might be: # <img src="/images/category4392.jpg" height=215 width=131 alt="Some i +mage"> %catData = (category => {database => 'UFMCatalog', table => '_5', field => 'image', noImage => '../images/no-image-long.jpg', mimetype => 'jpeg'}, productLarge => {database => 'UFMCatalog', table => '_4', field => 'largeImage', noImage => '../images/no-image-big.jpg', mimetype => 'jpeg'}, productSmall => {database => 'UFMCatalog', table => '_4', field => 'smallImage', noImage => '../images/no-image-small.jpg', mimetype => 'jpeg'}, logo => {database => 'ECinterface', table => 'logo', field => 'logo', noImage => '../images/1xshim.gif', mimetype => 'format'} ); $ENV{'QUERY_STRING'} =~ m!([a-zA-Z]+)(\d+)\.($types)$!; # Creates a "broken image" if the form of the image request is wrong $imageType = defined $1 ? $1 : exit; $imageID = defined $2 ? $2 : exit; $extension = defined $3 ? $3 : exit; # Creates a "broken image" if $imageType is not in %catData if (! exists $catData{$imageType}{field} ) { exit; } $image = getImage(); $image = getNoImage() if ! defined $image; print "Content-type: image/$mimeType{$extension}\n\n"; print $image; sub getImage { my $image; my $dbh = DBI->connect("dbi:ODBC:ourdb", 'ourdb', 'youwish', {RaiseError => 1}) or die DBI->errstr; $dbh->{LongReadLen} = 200000; $dbh->{LongTruncOk} = 1; my $sql = "SELECT $catData{$imageType}{field} " . "FROM $catData{$imageType}{database}..$catData{$imageT +ype}{table} " . "WHERE id = $imageID"; my $sth = $dbh->prepare($sql); $sth->execute; $image = $sth->fetchrow_array(); $sth->finish(); $dbh->disconnect; return $image; } sub getNoImage { my ($chunk, $image); open IMAGEFILE, "<$catData{$imageType}{noImage}" or die "Cannot open $catData{$imageType}{noImage}: $!\n"; binmode IMAGEFILE; while (read(IMAGEFILE, $chunk, 1024)) { $image .= $chunk; } close IMAGEFILE; # Since we're not getting the image we expected, reset the extensi +on to # the noImage extension to guarantee the correct MIME type is sent +. $catData{$imageType}{noImage} =~ /\.(\w+)$/; $extension = $1; return $image; } |
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