Notes To Self

FCK Editor – page break

Saltmeister — Fri, 01 May 2009 15:39:51 +0000

FCK editor is a great open source HTML rich text editor. I use it in a project that allows users to create documents within the browser (with additional server side logic) and then have the result streamed to Word on the client. This is done very cheaply by streaming the actual HTML to Word forcing a .doc extension. The hack works well apart from page breaks.

FCK editor adds the following HTML tags for a page break …

const string fckePageBreak = “

”;

const string wordPageBreak = “

”;

… which Word completely ignores.

Replace the default FCK tags above with the tags below before streaming to see your page breaks in Word …

http://www.fckeditor.net/

ASP.NET DataGrid – Live Long & Prosper!

Saltmeister — Thu, 12 Mar 2009 11:00:29 +0000

Ok, they are out of favour since the DataView came along in dotnet 2.0 but, if like me, you are still maintaining a project that has evolved since the dotnet 1.1 days, the DataGrid may still be a major part of your coding life. One day I’ll migrate to a new grid, maybe even a third party vendor, but that seems a lot of work for little gain when the current code is humming along quite happily.

There are some occasions where the DataGrid is lacking features though. For example, you may want to display a potentially large notes field per row, but adding it as a column can make the grid layout look ridiculous and waste browser real estate displaying the other columns.

For a recent enhancement to on of our projects, I needed a kind of expandable/collapsible “preview” row – the likes of which dev express grid fans might have come across on winform or delphi apps – where you can optionally display a large notes field, or additional address info per row. Another good example is MS Outlook with its “Auto Preview” mode.

So, I went about adding my own preview row to the trusty old DataGrid. It works by hacking some html table tags onto the end of the last column for each row.

In the code forward, I added a template column to the DataGrids Columns element and also added my over-sized notes as a hidden column.

The main part of the hack is in the code behind dg_ItemDataBound method:

private void dg_ItemDataBound(object sender, DataGridItemEventArgs e)
{
  if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
  {
    DataRowView drv = (DataRowView)e.Item.DataItem;
    if (drv == null) return;
    //hack a preview row
    HtmlImage iExpand = (HtmlImage)e.Item.FindControl("iExpand");
    iExpand.Attributes.Add("onClick", "TogglePreview('" + e.Item.ClientID.ToString() + "_salt', this);");
    e.Item.Cells[e.Item.Cells.Count - 1].Text +=
String.Format("
 var salthack='table-cell';
 if (IE6 || IE7) salthack='block';
 if (e != null){
 if (e.style.display == 'none'){
   e.style.display = salthack;
   e.style.visibility = 'visible';
  } else {
   e.style.display = 'none';
   e.style.visibility = 'hidden';
  }}}

Note the hacks for the CSS ”display” property. Firefox and Chrome both correctly support the table-cell selector but IE does not.

Bash syntax reminder #2

Saltmeister — Mon, 02 Mar 2009 10:40:13 +0000

If your scripts mount other drives in order to backup or mirror data, it is good practice (if not essential) to check whether the mount is successful before copying the data to it.

#example Bash syntax mounting a windows share & checking if the mount was successful

mount -t cifs //server/share /mnt/mymount -o username=x,password=y
if [ $? != 0 ]; then
echo “cannot mount share”
exit 1
fi
#otherwise continue script …

Failure to do this can result in a rogue script filling up /mnt/whatever with real data until the partition is full, which then can wreak havoc with other applications.

For example: Firebird was reporting: ”cannot start transaction for password database”.

Excel formula to calculate age

Saltmeister — Mon, 02 Mar 2009 10:35:52 +0000

This excel formula calculates the difference between two dates. Useful for a persons age, or years of employment service etc.

Assuming cell A1 = your date (date of birth for example)

=DATEDIF(A1,NOW(),”y”)&” years “&DATEDIF(A1,NOW(),”ym”)&” months “&DATEDIF(A1,NOW(),”md”)&” days”

Bash syntax reminder #1

Saltmeister — Mon, 02 Mar 2009 10:34:52 +0000

Locate some files, iterate thru the list and manipulate file & folder strings

#!/bin/bash

locate /home/myfolder/*today.zip >/tmp/salt

for file in $(< /tmp/salt)

#separate folder from file

filename=`basename $file`

folder=`dirname $file`

mkdir -p $folder #create parent folders if needed & don’t error if exists

#substrings

substr1=${folder:0:8} # gets first 8 chars

substr2=${folder:9} # gets from char 9 to end of string

#strip

parentfolder=${folder%/backup} #strips /backup from the end of the string

childfolder=${folder#/home} #strips /home from the start of the string

done

Firebird Superserver versus Classic & VMware

Saltmeister — Mon, 02 Mar 2009 10:25:55 +0000

Firebird Superserver versus Classic - running on Fedora 8 under VMware

Firebird superserver, with its shared cache always seemed to suit our many-databases & many-client requirements. But when we moved from physical servers to virtual servers, we hit a major performance problem.

Using a bash script that simultaneously queried several different large-ish databases, we found that performance was 3 times slower in the virtual environment than in the physical environment. But running the same script using Firebird Classic on Fedora-8 under VMware gave us the same performance as Superserver on our physical hardware.

Tip 1: in a typical installation, Classic is spawned from xinetd. On our Fedora 8 install, xinetd had a fairly low instance limit and began to prevent connections once the load increased, so check your xinetd.conf file’s access restriction defaults. If you have tons of headroom, the quick hack is:

instances = UNLIMITED
per_source = UNLIMITED
cps = 1000 10

Tip 2: lower the page & buffer sizes of your databases because with classic, cache is not shared per database. There is a separate cache for each connection.

Versions used at the time of writing this article: Firebird 1.5.5, Fedora 8, VMWare ESX 3.5

Further Info: Classic and Superserver Architectures Article

Firebird Support Group :http://tech.groups.yahoo.com/group/firebird-support/