Flex Datagrid Visibility Bug
Run into a nasty little bug with Flex datagrids the other, under some situations Datagrid columns with their visibility set to false will be displayed!
Here's a workaround.
Flex Filtering Long Lists
If you have a list box with a large number of items in it it can be hard for someone to find the item in the list that they need. One way around this is you add a filter on the list box.
Here's how it's done.
Flex Datagrid Edit Cell on Row Click
With flex datagrids you sometimes find you have a datagrid with multiple columns but only one or two columns are editable.
Which column are editable are not immediately apparent to a user, they have to click on cells to find out what's editable or not editable.
You can add some sort of visual indication to show what cells are editable (see here) OR you can make clicking on a row edit a cell.
Flex DataGrid Editing Cells
Flex datagrids provide an easy way to edit data. However one minor issue is that by default editable cells have no visual indication that they are actually editable.
You can add a graphical or textual indication that is a cell is editable with an item renderer.
ColdFusion Struct References
You need to be careful with references to objects or structs. I was looking at some old code the other day and I noticed I hadn't var'ed some local variables - very naughty of me. So I fixed the code but it no longer worked.
Flex Numeric Stepper with Currency
Flex's numeric stepper controls work well but will only work with numeric data so can't be used for editing currency.
Update - for a better solution look at the last code section
There's a few ways around the issues but none of the solutions are perfect.
Flex Webservices XML and Array Conversion
I'm currently working on a project involving simple webservices, the webservices return plain XML rather than using SOAP. Personally I prefer SOAP as you get a well defined interface but on this project it was felt that plain XML was less verbose, more efficient and easy to code server side.
Anyway one of the issues with returning XML via HTTPService calls is that when flex converts the XML to objects it treats it as array if there's more than one item of the same name but as a single item (ie not an array) if there's only one item of the same name.
This causes databinding to datagrids or lists to fail.
So how do you get around this issue?
ColdFusion Securing Databases (part 2)
In ColdFusion Securing Databases (part 1) we looked at restricting what sql statements can be run with a datasource and partitioning applications to use multiple datasources and multiple users to improve security. In this article we'll look at setting the permissions on the database tables.
ColdFusion Database Indexes
The most common problem I've run into with applications slow performance is the lack of indexes on the databases. Sometimes this is just because the application ran fine with a small amount of data but now is working off a larger amount, or the application is being used in unexpected ways (running less 'common' queries run more often), or the production environment doesn't have the same indexes as the development environment or worse case the indexes were never created in the first place.
Without indexes queries can take seconds with indexes they take milliseconds!
ColdFusion Securing Databases (part 1)
Most ColdFusion applications I'm come across tend to use a single datasource or if they use more than one the same user credentials are used. As well as causing possible performance and scalability issues this can be a security risk.
It's quite easy to restrict what SQL statements a datasource will run with the ColdFusion administrator.
