ch10_04.htm

用perl编写CGI的好书。本书从解释CGI和底层HTTP协议如何工作开始

  my $dbh = shift;

  my @value_array = (  );
  my @missing_fields = (  );

  my $field;
  foreach $field (@FIELD_NAMES){
    my $value = $cgi->param($field);
    if ($value) {
      push(@value_array, "'" . $value . "'");
    } else {
      push(@missing_fields, $field);
    }
  }

  my $value_list = "(" . join(",", @value_array) . ")";
  $value_list =~ /(.*)/;
  $value_list = $1;
  my $field_list = "(" . join(",", @FIELD_NAMES) . ")";

  if (@missing_fields > 0) {
    my $error_message = 
      qq`<STRONG> Some Fields (` . join(",", @missing_fields) .
      qq`) Were Not
            Entered!
            Address Not Inserted.
         </STRONG>`;
    displayErrorMessage($cgi, $error_message);

  } else {

    my $sql = qq`INSERT INTO $TABLE $field_list VALUES $value_list`;
    my $sth = $dbh->prepare($sql) 
           or die "Cannot prepare: " . $dbh->errstr(  );
    $sth->execute(  ) or die "Cannot execute: " . $sth->errstr(  );
    $sth->finish(  );
    
    displayMaintenanceChoices($cgi,"Add Was Successful!");    

  }

} # end of doAdd

sub doDelete {
  my $cgi = shift;
  my $dbh = shift;

  my $delete_criteria = $cgi->param("delete_criteria");
  if (!$delete_criteria) {
    my $error_message = 
      "<STRONG>You didn't select a record to delete!</STRONG>";
    displayErrorMessage($cgi, $error_message);
  } else {

    my %criteria = (  );

    my @field_values = split(/\|/, $delete_criteria);  
    for (1..@FIELD_NAMES) {
      $criteria{$FIELD_NAMES[$_ - 1]} = 
        $field_values[$_ - 1];
    }

    # build up where clause
    my $where_clause;
    $where_clause = join(" and ", 
                    map ($_ 
                         . " = \"" 
                         . $criteria{$_} . "\"", (keys %criteria)));
    $where_clause =~ /(.*)/;
    $where_clause = $1;


    my $sql = qq`DELETE FROM $TABLE WHERE $where_clause`;
    my $sth = $dbh->prepare($sql) 
           or die "Cannot prepare: " . $dbh->errstr(  );
    $sth->execute(  ) or die "Cannot execute: " . $sth->errstr(  );
    $sth->finish(  );
    
    displayMaintenanceChoices($cgi,"Delete Was Successful!");    

  }

} # end of doDelete

sub doUpdate {
  my $cgi = shift;
  my $dbh = shift;

  my $update_criteria = $cgi->param("update_criteria");
  if (!$update_criteria) {
    my $error_message = 
      "<STRONG>You didn't select a record to update!</STRONG>";
    displayErrorMessage($cgi, $error_message);
  } else {

    # build up set logic
    my $set_logic = "";
    my %set_fields = (  );
    my $field;
    foreach $field (@FIELD_NAMES) {
      my $value = $cgi->param($field);
      if ($value) {
        $set_fields{$field} = $value;
      }
    }
    $set_logic = join(", ", 
                 map ($_ . " = \"" . $set_fields{$_} . "\"",
                 (keys %set_fields)));
    $set_logic = " SET $set_logic" if ($set_logic);
    $set_logic =~ /(.*)/;
    $set_logic = $1;

    my %criteria = (  );

    my @field_values = split(/\|/, $update_criteria);  
    for (1..@FIELD_NAMES) {
      $criteria{$FIELD_NAMES[$_ - 1]} = 
        $field_values[$_ - 1];
    }

    # build up where clause
    my $where_clause;
    $where_clause = join(" and ", 
                    map ($_ 
                         . " = \"" 
                         . $criteria{$_} . "\"", (keys %criteria)));
    $where_clause =~ /(.*)/;
    $where_clause = $1;


    my $sql = qq`UPDATE $TABLE $set_logic` .
                  qq` WHERE $where_clause`;

    my $sth = $dbh->prepare($sql) 
           or die "Cannot prepare: " . $dbh->errstr(  );
    $sth->execute(  ) or die "Cannot execute: " . $sth->errstr(  );
    $sth->finish(  );
    
    displayMaintenanceChoices($cgi,"Update Was Successful!");    

  }

} # end of doUpdate

sub displayEnterNewAddressScreen {
  my $cgi = shift;

  displayNewDeleteUpdateScreen($cgi, "ADD");

} # end of displayEnterNewAddressScreen

sub displayUpdateQueryScreen {
  my $cgi = shift;
 
  displayNewDeleteUpdateScreen($cgi, "UPDATE");

} # end of displayUpdateQueryScreen

sub displayDeleteQueryScreen {
  my $cgi = shift;

  displayNewDeleteUpdateScreen($cgi, "DELETE");

} # end of displayDeleteQueryScreen

sub displayNewDeleteUpdateScreen {
  my $cgi       = shift;
  my $operation = shift;

  my $address_op = "Enter New Address";
  $address_op = "Enter Search Criteria For Deletion" if ($operation eq "DELETE");
  $address_op = "Enter Search Criterio For Updates" if ($operation eq "UPDATE");

  print $cgi->header(  );

# Prints out the header
print qq`
<HTML><HEAD>
<TITLE>Address Book Maintenance</TITLE>
</HEAD>
 
<BODY BGCOLOR="FFFFFF">
 
<H1>$address_op</H1>

<HR>
<P>
<FORM METHOD=POST>
`;

if ($operation eq "ADD") {
  print "Enter The New Information In The Form Below\n";
} elsif ($operation eq "UPDATE") {
  print "Enter Criteria To Query On In The Form Below.<P>\nYou will then be 
  able to choose entries to modify from the resulting list.\n";
} else {
  print "Enter Criteria To Query On In The Form Below.<P>\nYou will then be 
  able to choose entries to delete from the resulting list.\n"
}

my $address_table = getAddressTableHTML(  );
print qq`
<HR>
<P>

$address_table
`;

if ($operation eq "ADD") {
      print qq`
      <P>
      <INPUT TYPE="submit" NAME="submit_add" 
      VALUE="Add This New Address"><P>
      `; 
} elsif ($operation eq "UPDATE") {
      print qq`      <INPUT TYPE="checkbox" NAME="exactsearch">
      <STRONG>Perform Exact Search</STRONG>
      <P>
      <INPUT TYPE="submit" NAME="submit_query_for_update"
      VALUE="Query For Modification">
      <P>
      `;
} else {
      print qq`
      <INPUT TYPE="checkbox" NAME="exactsearch">
      <STRONG>Perform Exact Search</STRONG>
      <P>
      <INPUT TYPE="submit" NAME="submit_query_for_delete"
      VALUE="Query For List To Delete">
      <P>
      `;
}

# print the HTML footer.

print qq`
<INPUT TYPE="reset" VALUE="Clear Form">
</FORM>
</BODY></HTML> 
`;

} # end of displayNewUpdateDeleteScreen
sub displayErrorMessage {
  my $cgi = shift;
  my $error_message = shift;


  print $cgi->header(  );

  print qq`
<HTML>
<HEAD><TITLE>Error Message</TITLE></HEAD>
<BODY BGCOLOR="WHITE">
<H1>Error Occurred</H1>
<HR>
$error_message
<HR>
</BODY>
</HTML>
`;

} # end of displayErrorMessage

sub getAddressTableHTML {

return qq`
<TABLE>
<TR>
  <TD ALIGN="RIGHT">First Name:</TD>
  <TD><INPUT TYPE="text" NAME="fname"></TD>
</TR>
<TR>
  <TD ALIGN="RIGHT">Last Name:</TD>
  <TD><INPUT TYPE="text" NAME="lname"></TD>
</TR>
<TR>
  <TD ALIGN="RIGHT">Phone:</TD>
  <TD><INPUT TYPE="text" NAME="phone"></TD>
</TR>
<TR>
  <TD ALIGN="RIGHT">Department:</TD>
  <TD><INPUT TYPE="text" NAME="dept"></TD>
</TR>
<TR>
  <TD ALIGN="RIGHT">Location:</TD>
  <TD><INPUT TYPE="text" NAME="location"></TD>
</TR>
</TABLE>
`;

} # end of <a name="INDEX-2174" />get<a name="INDEX-2,175" /><a name="INDEX-2,176" />Address<a name="INDEX-2,177" /><a name="INDEX-2,178" />TableHTML</pre></blockquote>


<p>You probably noticed that the style of this CGI script is different
from other examples in this book. We have already seen scripts that
use CGI.pm, Embperl, and HTML::Template. This script uses quoted
HTML; you can compare it against other examples to help you choose
the style that you prefer.</p>


<p>Likewise, this CGI script is one long file. The advantage is that all
of the logic is present within this file. The disadvantage is that it
can be difficult to read through such a long listing. We'll
discuss the pros and cons of unifying applications versus breaking
them into components in <a href="ch16_01.htm">Chapter 16, "Guidelines for Better CGI Applications"</a>.</p>
</div>
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