Thymeleaf - Passing Variables From Child To Layout
Just a quick update after my last post to clarify things a bit. I mentioned in that post my dismay regarding the inability to pass model variables from the child view to the parent layout - and I shared that concern with the dialect developer Emanuel on GitHub. He quickly wrote back to clarify that it is indeed possible:
Hi Todd! First of all, nice blog - I came across it the other day when you wrote about using Thymeleaf w/ Spark \
Anyway, as for passing values from child templates up to their parent layouts, it’s possible using Thymeleaf’s
th:withattribute processors on any element that’s involved in the layout/decoration process, which would be anywherelayout:decorateorlayout:fragmentwill be found. eg:Child/content template:\
<html layout:decorate="your-layout.html" th:with="greeting='Hello!'">::: :::
Parent/layout template:\
<html> ... <p th:with="$"></p> <!-- You'll end up with "Hello!" in here -->::: :::
Now, I don’t seem to have documented this anywhere, and as someone who takes some pride in writing good docs, I feel a little bad that I’ve missed this! I swear I used to have it somewhere because others have come to me whenever this feature is broken/missing or they couldn’t get it to work.
Of course I had to quickly test this out back in my Spark Java application, so I went back to the thymeleaf-layout.html view and modified it to pass the menu variable from my model into the layout:
<html xmlns:layout="http://www.ultraq.net.nz/thymeleaf/layout"
layout:decorate="~" th:with="nav=$">
Here I’m declaring that in the parent layout there should be a variable called nav that contains the value of menu from my model. Now in the layout file (main.html) I can reference the nav variable to create my menu:
<ul class="nav navbar-nav">
<li th:each="i : $"><a th:href="@}"><span th:text="$"></span></a></li>
</ul>
And I’m in business! It’s great to see an open source developer so responsive and concerned with proper documentation. Thymeleaf definitely has potential.
\