Wizard of X

I was asked to create a control that would allow users to select the number of rows per page in a view/repeat control (the application uses both). It seemed simple at first, but I ran into a few issues that I thought I'd share the solutions to. Problem 2: When the page refreshed, the combobox value always reverted back to the default It turns out that the Integer value stored in the viewScope doesn't get run through the converter back to a string before being compared to options. I needed a way to calculate the option values so that they would be Integers. This is also not the first time I've run into issues where I need a value to be of a different type, and I see questions like this on StackOverflow from time to time. I attempted a few minor things before I realized I needed to break out my old stand-by, the GetMap . The GetMap is just a fake Map implementation that takes the key and transforms it or uses it to look up some other value. In this case, we are doing the f...

I was asked to create a control that would allow users to select the number of rows per page in a view/repeat control (the application uses both). It seemed simple at first, but I ran into a few issues that I thought I'd share the solutions to. First, lets start at the beginning. I went through the relevant design elements and set row="#{viewScope.tableRows}" , and I created an xp:comboBox with value="#{viewScope.tableRows}" and added items for 20, 30, 50, and 100, and I assigned it an onChange event handler that did a partial execution and partial refresh of a div containing the combo box, pager and the table. Then I started fixing all the problems. Problem 1: The combobox value was a string, but the rows parameter requires an integer. This was causing IllegalArgumentException / java.lang.String incompatible with java.lang.Integer. I added a NumberConverter, but this only slightly changed the exception message to java.lang.Long incompatible with java.lang....

I just had a need to do this and a Google search didn't immediately turn up a solution. So I thought for a couple of minutes and came up with this: value="0#{numberVar}" This takes advantage of the way Java auto-converts objects to strings when doing a concatenation. So if your number is 13, Java EL turns this into new String("0"+13), which becomes "013". You can then strip off the leading zero or just parse the string back into a number.

In my last post, I offered a very rough overview of the framework I've been building and adapting. Full credit where it's due, I've been borrowing and adapting from Jesse Gallagher's XPages Scaffolding - an awesome project that I've learned a great deal dissecting. This is one of those projects that, if you make the effort to truly understand it, will give you entirely new tools and approaches for problems. As usual, I've learned the most changin g things and breaking them. My project differ s f rom Jesse's mostly in that it supports 8.5.3 and doesn't require any relaxed security permissions - bec ause I'm on 8.5.3 and because the admins h ere will not grant any relaxed permissions.

In part 1, I showed how you can expand the DataObject implementation to allow you to pass a parameter to a method and return the result. It's not a perfectly elegant solution, and it has some limitations, but it's a very solid technique and not at all difficult to implement or maintain. But I kept running into roadblocks. What if I have to compute part of the expression? What if I have to get a value based on another parameterized getter? You can't compute part of an EL expression in your EL. So after some research and experimentation, I created the GetMap. This isn't a new concept - it was developed for JSF 1.1 (which is what XPages is built on) but the rest of the world has moved on to JSF 2.0 and so some of these older techniques can be a little tricky to unearth since this hasn't been an issue in the JSF world for years.

Expression Language is a powerful and useful tool, but it doesn't handle parameterized methods (other than Map.get(Object) and DataObject.getValue(Object)). That means if you need to do anything more complicated than simple data retrieval, you have to jump through some hoops. I'm going help you get started here.

Note: I changed projects and priorities after my last POI article, resulting in a long hiatus. I anticipate using that framework on my current project and will likely refine and complete my related article series. For the past several months, I've been fortunate enough to lead a project overhaul from traditional Domino Webapp to XPages. I had a few goals in mind, but the top three were integrating Bootstrap, embracing MVC principles, and eliminating all SSJS . I imagine the motivation for Bootstrap integration is self-explanatory. There is an OpenNTF project out there called Bootstrap4XPages. I didn't use that for a number of reasons - the main being a policy in the current environment. But you may ask yourself (if you didn't follow that link), why so much hatred for SSJS? I have a litany of reasons. It impacts readability of the XPage source; it hurts maintainability when logic is scattered across dozens of XPages, custom controls, and script libraries; it mixes log...