Here are the results of my exploration of Jwt tables with Clojure. The code is inspired by an example in the Jwt sources.

A table in Jwt is created with WTreeView

 let [ tree-view (WTreeView.) ]

and the columns are configure in a model object. In my case, I'll use the WStandardItemModel . When instanciating the model, you tell it how many row and columns it should have, in this case 0 rows (I don't know yet why I should pass anything else than 0 here) and 4 columns:

 (WStandardItemModel. 0 4)

Once the model is intanciated, we can set the column headers with the setHeaderData method:

 (.setHeaderData model 0 Orientation/Horizontal "Places")
 (.setHeaderData model 1 Orientation/Horizontal "Weather")
 (.setHeaderData model 2 Orientation/Horizontal "Drink")
 (.setHeaderData model 3 Orientation/Horizontal "Visited")

Now we should add data to the table! A data row is represented by a list of WStandardItem objects, each being the data displayed in a column, so in our case we'll have each row represented by a list of 4 elements. A list? That's perfect for Clojure! I'll build a list of the items I want in the table and map them to a list of WStandardItems, like this:

 (map #( WStandardItem. % ) '("Leuven" "Rain" "Beer" "Yes") )

For the fun I defined a function building the WStandardItem:

 (defn standard-itemize [ item ]
   (WStandardItem. item))

Which lets me write this code to build a row:

(map standard-itemize '("Leuven" "Rain" "Beer" "Yes") )

When we have the row, we can add it to the table with appendRow :

 (.appendRow model row)

We can the set assign this model to the tree-view with :setModel

 (.setModel tree-view model)

Once we know that, it's trivial to work on list of rows:

(let [data'(("Leuven" "Rain" "Beer" "Yes")("Brussels" "Rain" "Beer" "Yes")) )
 rows (map #( map standard-itemize %) data)]
....
(doall (map #(.appendRow model %) rows))

With a function I called standard-rowize taking a row of data and returning a row of WStandardItems, we get somewhat cleaner code:

(defn standard-rowize [ row ]
 (map standard-itemize row))


 (let [data'(("Leuven" "Rain" "Beer" "Yes")("Brussels" "Rain" "Beer" "Yes")) )
 rows (map standard-rowize data)]


 ... 
 (doall (map #(.appendRow model %) rows))

Here's the result, a table with row ordering and alternating row colors

But there's more to it than this. As the table is represented by a tree view, it can group rows and that is achieved really easily: each row can be the container of its sub rows! Here are the only changes to do:

Create a europe-row which will contain european cities

europe-row (WStandardItem. "Europe")

appends the rows to the europe-row rather than to the model:

(doall (map #(.appendRow europe-row %) rows))

and finally, append the europe-row to the model:

(.appendRow model europe-row)

This is all what's needed to get this:

The changes were so small that despite the fact that I discovered all this, it worked at the first try! Here's the code of the function buidling the tree-view:

(defn build-tree-view []
 ( let [ tree-view (WTreeView.)
 model (WStandardItemModel. 0 4)
 europe-row (WStandardItem. "Europe")
 rows (map standard-rowize '(("Leuven" "Rain" "Beer" "Yes")("Brussels" "Rain" "Waffles" "Yes")) )
 ]
 (.setHeaderData model 0 Orientation/Horizontal "Places")
 (.setHeaderData model 1 Orientation/Horizontal "Weather")
 (.setHeaderData model 2 Orientation/Horizontal "Item")
 (.setHeaderData model 3 Orientation/Horizontal "Visited")
 (.setAlternatingRowColors tree-view true)
 (doall (map #(.appendRow europe-row %) rows))
 (.appendRow model europe-row)
 (.setModel tree-view model)
 tree-view))

Let's go further and manipulated the table: let's add a button to toggle the alternated row colors. Again, the changes to make are minimal:

• instanciate a WPushButton
• instanciate a WContainerWidget and pass it as the parent widget to the button and treeview constructor
• return the container in place of the treeview
• add a listener to the click event of the button to toggle the rows coloring. This uses the macro written for the Jwt-Clojure previous post.

Here is the code where I indicated the lines that were added or adapted:

(defn build-tree-view []
 ( let [ 
 container (WContainerWidget.) ;added
 button (WPushButton. "Toggle colors" container) ;added
 tree-view (WTreeView. container) ;adapted
 model (WStandardItemModel. 0 4)
 europe-row (WStandardItem. "Europe")
 rows (map standard-rowize '(("Leuven" "Rain" "Beer" "Yes")("Brussels" "Rain" "Waffles" "Yes")) )
 ]
 (.. button clicked (addListener container (create-listener [mouse-event]
 (.setAlternatingRowColors tree-view (not (.hasAlternatingRowColors tree-view) ))))) ; added
 (.setHeaderData model 0 Orientation/Horizontal "Places")
 (.setHeaderData model 1 Orientation/Horizontal "Weather")
 (.setHeaderData model 2 Orientation/Horizontal "Item")
 (.setHeaderData model 3 Orientation/Horizontal "Visited")
 (.setAlternatingRowColors tree-view true)
 (doall (map #(.appendRow europe-row %) rows))
 (.appendRow model europe-row)
 (.setModel tree-view model) ;adapted
 container)) ;adapted

Although there's a lot more to explore (pagination being the first thing I want to explore next), this is is for now. I hope this encourages to test Jwt and Clojure, both being very exciting projects!