AJAX and ThymeLeaf For Modal Dialogs

The final part of the basic phonebook application is being able to click on a person and see details about them. For this part I’ve decided for now not to open a new page but to open the persons details in a modal dialog box on the current screen just so I can demo how to do ajax calls using Spring and Thymeleaf.

First of all I need a PersonController which will populate the modelmap with the selected persons attributes and then return a thymeleaf page.

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This controller is very simple and very like all the other controllers it will respond on the /person/{Id} path and populate the modelmap with details of the selected person. I’m also adding in attributes for the person’s manager and their co-workers. The most important part however is the returned string at the end. In the other controllers I just returned a simple string that would match up to the thymeleaf html page that I wanted to render. This time, however, I have added a fragment name separated from the page name by a double colon. When this controller is called only a spamm portion of the modal/person.html page will be returned to the browser. Here is the corresponding fragment…

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To get the modal dialog to display I have added an onClick event to the table row which will run a function called openPersonModal and pass in that rows person id number.

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The function called the Spring MVC controller and is returned just the fragment of html code from Thymeleaf. I then pop this in to an empty div called personModalHolder which I had also added to the page and then I call the bootstrap function to show the modal.

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At this stage we have a very simple, read only, phonebook using our auto generated test data. For the next few posts I’m going to take a break from writing code and I’m going to show how to create a pipeline in VSTS and Rancher and Docker to auto build and deploy our application. After that we will come back to the app to add some additional features to allow for editing and adding new people.

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Posted in Domino To Spring

Highlighting The Selected Area With Thymeleaf

Now that I have pulled the side navigation menu out in to its own reusable code fragment I can now make a small adjustment to it to highlight the currently selected option in the navigator. In the Domino/XPage world this would be the script that you write to add a css class to a menu item using the selected property.

For the bootstrap based side navigator that I am using in this application you can add a background color to the side navigator by adding a css class of ‘active’ to the list item tag. Currently our side navigator fragment looks as follows.

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The list item tags for both the home link and the location links do not have any class associated with them at this stage.

Using Thymeleaf you can use a conditional expression to set the class. A conditional expression if pretty much like a simple If/Then/Else statement like th:class=”${row.even}? ‘even’ : ‘odd'”, You can also use nest conditional expressions using parenthesis like th:class=”${row.even}? (${row.first}? ‘first’ : ‘even’) : ‘odd'”. You can also leave out the else part if you want which is what I have done in my code.

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To get this working correctly I had to add a new attribute to the model in both my home controller and my location controller called selectedLocation. It is manually set to ‘Home’ in the home controller and it is programmatically set to the location name in the location controller.

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Now my phonebook correctly shows the currently selected area as highlighted in the side navigator.

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Posted in Domino To Spring

Reuse More Code With ThymeLeaf Layouts

As you saw in the last entry you can use ThymeLeaf Fragments to split out reusable parts of your html pages so that you can just drop them in where needed just like Custom Controls in XPages. Another great XPage concept was using a Custom Control to design the main layout of your page and then drop the content for the page that you are displaying in to a facet on that custom control. With an add-on to ThymeLeaf, which is automatically supplied when using ThymeLeaf with SpringBoot, this is also easily achievable.

I’ve created a new folder in my resources section called ‘layouts’ and I’ve pulled over a copy of my homepage that I will convert in to a layout.  I forst need to add the xml namespace in to the HTML tag and then I can add a div with a tag of layout:fragment to the sections that will be replaced with the content that I’m supplying.

You will also see that I’m still including some ThymeLeaf fragments as defined in the last blog entry, and I have changed how the head tag is setup by adding in a th:block ( because div is invalid in the head tag )  and for the title tag I now have a new layout:title-pattern tag that allows me to programmatically define the title using a combination of the layouts title and then contents title.

Over on my home page I can now add the same namespace and also specify which layout I will be using by adding in a layout:decorate tag.

The system will now merge the <head> elements from both the layout and the content pages  and then replace the layout fragments in the layout page with the layout fragments in the content page while ignoring anything else in the content page that is not part of the fragments.

Over on my location page you can see where I am adding a ThymeLeaf fragment in the header for the DataTables CSS and where I have specified the custom-footer fragment so that I can also add in the DataTables scripts.

As you can see a combination of ThymeLeaf Fragments and ThymeLeaf Layouts is very powerful and this is just scratching the surface of what ThymeLeaf can do.

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Posted in Domino To Spring

Introducing ThymeLeaf Fragments

When I created my people by location page I just copied the entire home page of the application. I now want to make a few changes to the side navigator but if I leave things as they are now I would have to make those changes in all pages that share the side navigator. In the XPages world we had custom controls which could be used to break your page in to separate components and ThymeLeaf has a similar concept called Fragments.

Under my templates folder I’m going to create a new folder called fragments and in there I’m going to add a new html page called layout.html. I’m then going to move the html that makes up the side navigator to this html file and add in an extra ThymeLeaf tag.

This tag identifies the div and everything between it and the closing div as the fragment called ‘sidenav’.

Now back on both the home and location pages I can replace that entire block of code with one simple line.

This tag tells the ThymeLeaf processor to replace this entire div ( and anything in the div ) with the fragment called ‘sidenav’ from the file called layout in the fragments folder.

If you restart the application now you won’t see any changes on the page but the side navigation bar is no longer duplicated across multiple pages so if you need to change it then you just have to update one file.

You can add as many fragments as you want to a single fragment file or you could split them up in to different files. You could even use fragments to set all your head tags or load your scripts. I’ve setup a fragment for my global scripts and I have added an additional ThymeLeaf tag of th:remove=”tag”.

What this does is it will remove the

tags and only render the contents which, in this case, are the two script tags.

If you are using a fragment to setup all your css then you may run in to the issue of how to set a page title. To do this you can add parameters to a fragment. Here I’ve added a pageTitle parameter and I’m using it in the title tag.

When I call this fragment I can then pass in a value to the parameter.

or you could even calculate a title using a ThymeLeaf Expression

So now you can break your application up in to smaller chunks and make reusable code sections for the frontend.

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Posted in Domino To Spring
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