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Flex: Using A SharedObject to Remember User Settings
Try this:
- Open the Contact Manager app.
- Change the columns that are visible by using the "column chooser" button, as below:
- Quit the browser.
- Re-open the browser and visit the app again.
- Notice how the visible columns are the same ones as before you closed the browser!
The View component I've been developing recently now uses the Flex equivalent to the cookie - the SharedObject - to remember your choice of columns across sessions.
Note that the same column preferences are shared across all browsers on your PC as the SharedObject is per Flash player install rather than per browser.
For now it won't remember your preferred order of columns (did you know you can drag and drop columns to change the order!?). I'll work on that. The updated demo now remembers the order of your columns! Nor does it remember the width of them. I'll work on that too.
In the mean time here's the updated source code for both the Domino database and the Flex source code. Enjoy. More to come...
...can anybody think of anything else this View component is lacking before I can consider it a universal solution for all your Notes-to-Flex migration tasks?
4/9 Comments Read - Add | Wed 10 Mar 2010 | Open »
Flex: A Toggle-Style Column Component for Your Views
Adding even more functionality to Flex "view" I've been building I've now added a "toggle column" to the list of available column types:
The idea is simple. You click the icon in the column to toggle a field value on the back end document. The icon in the view is either on or off and is dictated by the value stored in the field. It's an idea I've mentioned before which I've now made into a re-usable and customizable component.
In this example I'm using the idea of being able to mark certain contacts as favourites and you can see a working example in the Contact Manager app. The component itself can be re-used in almost any scenario though.
Adding a toggle column to a View is as simple as adding one line of XML to the View's configuration, which is specified in the backend Domino database, as discussed previously.
The XML looks like this:
As you can see it's fairly easy to configure and customize. You can easily change the icon, field name and what the "on"/"off" values should be for the field. You can also add a tooltip for the column.
The Column value of "starred" refers to the name of the XML node of each document which holds the field value we're interested. When the grid is first loaded it will show the icon as on or off depending on the value in the "starred" node.
Clicking on the toggle column on sets the value of the field called "Favourite" to "1". Clicking it again sets the value to "".
To see the XML used in the demo open the Contacts view as XML. This is the XML format that defines the structure and data of the View component. Simple, no?
Taking It Further
If you want to go further than simply modifying a single field at a time and want to perform a more involved action then you can do what I tend to always do and add a self-referencing "computed for display" field to the backend Domino form called something like "Action". In the WQS agent you can then check the value of this field. If the value is something like "Approve" then you can run a set of actions against the document.
In this scenario the XML data for each row just needs to define a true/false value to let Flex know whether to show the icon as on or off depending on whether it's approved or not. The value for the fieldValueOn would be "Approve" and for fieldValueOff it would be "Unapprove". The actual XML data for approved documents would be "Unapproved" and for unapproved documents the column value would be "Approve". If that makes sense.
Summary
It's the simple little components like this that show how powerful Flex can be once you get going with it. With the View component and the components I'm adding to it I feel like this is getting to the point where it's a viable product that can be re-used in live applications. In fact I already am using it in live applications for paying customers.
In the next couple of days I'll update the downloadable version of the app with updated Flex source code. Before I do I want to blog about another addition to the code -- the ability to store a user's choice of columns across sessions using the Flash/Flex equivalent of cookies - the SharedObject. Give me a day or three.
Update: Here's the updated source code and Domino db.
3/4 Comments Read - Add | Tue 9 Mar 2010 | Open »
Domino's POP3 Server Breaks HTML Emails by Removing Characters
There's a bug when sending and retrieving HTML email from Domino that has been plaguing me for years now. Now I've finally decided to take the time to investigate fully and find a fix.
First, imagine the code below:
While i<100 j = 0 html ="" While j<i html = html + "split string " j=j+1 Wend Set mail = New Email() mail.Subject = "Test " + CStr(i) mail.HTML = html mail.Send("jake howlett") i=i+5 Wend
What this does is send me 20 test emails. Each email is increasingly longer than the one before it and they all just repeat the words "split string" over and over.
The code to send the email is based on my Email class. All it does is create a multi-part MIME message. Nothing out of the ordinary. If you're using the MIME classes to send emails then this probably applies to you.
At some point in the loop the length of the message will get to such a size that something very worrying happens, as you can see below:
Notice the missing p?!
The Problem
From my investigations I've concluded the following:
If you use a 3rd party mail client (like Thunderbird) to download a multi-part HTML email from a mail file on a Domino server using POP3 then the POP3 server will remove the 655th character and put a line break in its place.
Looking at the very same email in the original mail file - using the Notes client - there's no missing character.
What I've also noticed is that it only removes the first 655th char. Not every subsequent 655th char in the whole string.
Obviously this can be very, very bad. At it's least worst, like in this example, it just looks like a typo. However, I've had numerous bug reports because it's broken the string inside an HTML tag, resulting in un-clickable links or -worse still - emails that just show raw HTML.
The problem seems only to occur when sending emails where the HTML content is made up of one very long string. I guess using very long strings is generally a bad idea in any case, but there's nothing actually wrong with it, and nothing half as wrong as the server removing characters.
The Solution
What we need to do is avoid very long lines of HTML code in the email. The obvious solution is to add line breaks in the HTML as you build it in your code.
Unfortunately, in my case, I have way too many instances of code sending HTML email to make it practical to go and add new line breaks in to each email. Instead, what I did was put a fail-safe in to the Email class which sends the email. At the point it adds the HTML to the email it adds a new line at every point an HTML tag is closed, like so:
Call stream.WriteText(Replace(Me.str_HTMLPart, ">", ">"+Chr(10)))
There's still a slight chance that there could be a long string that avoids this rule, but it's unlikely enough for me to feel happy this has resolved the issue for now.
Summary
So, you've been warned. If you're sending HTML emails to a Domino server, make sure you split the HTML string down in to sizeable chunks so that users who access their email via POP3 don't see broken HTML.
It all leaves me wondering why on earth the POP3 server would replace the 655th character in the first place. Assuming it does of course. My investigation wasn't exactly extensive but, from what I can tell, it definitely looks like it does. Why though? What's significant about 655? It's not like it's a base 2 number or anything.
9/20 Comments Read - Add | Wed 3 Mar 2010 | Open »
How Many Programming Languages Is It Possible To Know?
As I go about learning to develop with ASP.NET I can't help thinking what I think about every time I start learning a new programming language or skill -- does my head have the space for all the new information?!
While I'm sure the amount of knowledge currently stored in my head doesn't even come close to pushing the limits of the human brain I do sometimes feel a bit over-whelmed when I consider how much knowledge I need to retain in order to do my daily job.
It all makes me think of the age-old saying:
Does adding yet another skill to my tool belt mean I'll be just a little less able at one of those I already use?
Or, just as worrying, does learning something new mean something else is forgotten. Gotten rid of to make space. I remember reading that Einstein used to try and forget the phone numbers of people he no longer called, so that space was freed-up for something else.
Perhaps we each have our own amount of RAM that can be used. Perhaps this decreases with age. Perhaps I should consider stopping trying to learn more than I really need to and concentrate on getting better at the ones I do know.
Anybody ever think like this or, as I expect, am I just weird?
16/28 Comments Read - Add | Mon 1 Mar 2010 | Open »
Say Hello To Evelyn Howlett
Yesterday morning at 5-something o'clock Karen woke up in the early stages of labour. Within minutes I'd called the midwifes. Remember last time we'd planned a home birth for Minnie, but left it too late to call and ended up speeding to hospital in an ambulance. Didn't want to repeat that experience.
It was a good job I called so soon, as it had snowed during the night and the midwife on call had to come from a town about 14 miles away, which took her an hour. An hour after she arrived, so did Evelyn.
Here's a photo of her in the style of the one of Felix and of Minnie on the days they were born. She looks a lot more like her brother than her sister.
The birth was all very straight-forward, which I guess it's easy for me to say. Mother and baby are doing well.
My plan is to work from the house for at least this week and just spend an hour or so at the laptop each day to keep on top of things. At least that's the plan.
52/55 Comments Read - Add | Mon 22 Feb 2010 | Open »
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