Why "checked" attribute doesn't apply to my Thymeleaf's checkboxes? - spring

Question

I was working with Spring and Thymeleaf when I've encountered the following problem: I need a Form object, which has a list of items (Item) as attribute; I'm using an html form to print the Name of the Item, and to generate a checkbox for each Item (any checkbox's value is the corresponding item's id).
The form works correctly, sending to the Controller a list of item's ids corresponding to the checked checkboxes.
However, now, I'm trying to check some checkbox upon the occurrence of a condition (if itemIds, which is a list, contains the current item's id). For that I'm using:
th:checked="${#lists.contains(itemIds, item.id)}"/>
But it doesn't work (checkbox are all unchecked).
I tried also with a "dummy test":
th:checked="${1 == 1 ? 'checked' : ''}"/>
But, again, all the checkbox remain unchecked; the "checked" attribute is ignored as you can see in this example of the rendered HTML:
<input type="checkbox" value="12" class="chkCheckBox" id="ids1" name="ids">
What am I doing wrong? What am I missing here?
form.html
<form th:action="#{${uriBase}+'/new/' + ${date}}"
method="POST" th:object="${form}">
<div class="table-responsive">
<table class="table">
<thead class=" text-primary">
<tr>
<th>Name</th>
<th><input type="checkbox" th:id="checkAll"/>Check</th>
</tr>
</thead>
<tbody>
<tr th:each="item : ${items}">
<td th:text="${item.name}"></td>
<td>
<input type="checkbox" th:field="*{ids}"
th:value="${item.id}" th:class="chkCheckBox"
th:checked="${#lists.contains(itemIds, item.id)}"/>
</td>
</tr>
</tbody>
</table>
<button type="submit" class="btn btn-primary pull-right">Submit</button>
<div class="clearfix"></div>
</div>
</form>
Form class
public class Form implements Serializable {
private List<Long> ids;
//getter and setter
}
Thank you in advance.

Answer 1

I have been struggling with this as well. If you use the th:field it will override the checked and value options, as Xaltotun mentions, because it is trying to get the value and checked option from the field/form.
If you change it to th:name it should work how you want...
But this forum seems to be helpful for doing it with th:feild.

Answer 2

As far as I understand there are 2 issues in your post:
The dummy example is incorrect.
th:checked="${1 == 1 ? 'checked' : ''}"
In fact the value must true or false not 'checked'. If you try with
th:checked="${1 == 1}"/>
It will work.
If you set th:field="*{ids}" then the checkbox should be trying to get the value from the field item.ids and will not use the "th:checked" or "th:value" properties. Does the item has the field ids?