Spring Thyme Leaf checking for global errors results in NPE

Question

To display global errors created with Spring MVC with Thyme Leaf, I tried the example given at http://www.thymeleaf.org/doc/tutorials/2.1/thymeleafspring.html#global-errors:

That, is:

<div th:if="${#fields.hasGlobalErrors()}">

and

<ul th:if="${#fields.hasErrors('global')}">

and

<div th:if="${#fields.hasGlobalErrors()}">

When I add them to my HTML, the page won't even render, nevermind about submitting the form. All the examples result in:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#fields.hasErrors('global')"

I tried this with v2.1.4 and v.2.1.3 and got the same error. Bug or am I doing something wrong?

Yes, the tags are all closed and properly formed. Yes, this code was within a form. Yes, all the other aspects of the form work without the global error check.

Here is a short version of broken HTML:

<form action="search.html" th:action="@{/auto/search}">
<p th:if="${#fields.hasErrors('global')}" th:errors="*{global}">
    Incorrect date
</p>
<input type="text" th:field="${command.stockNumber}" />
<select th:field="*{command.startYear}">
    <option value="" th:each="year : ${modelYears}" th:value="${year}"
            th:text="${year}"></option>
</select>
</form>

And the controller..

@RequestMapping(value = "/auto/search", method = RequestMethod.POST)
public String search(@Validated
                     @ModelAttribute("command")
                     AutoSearchCommand autoSearchCommand
                     BindingResult result, Model model) {
    return "search";
}

score 5 · Accepted Answer · edited May 23 '17 at 11:59

Solved:

th:object is needed in a tag preceding to the global error check. Unfortunately, this isn't mentioned in the Spring Thyme Leaf tutorial. Presumably, there's a default form name somewhere which I've overridden in my controller.

Adding the tag in results in this working html:

<form action="search.html" th:action="@{/auto/search}">
<div th:object="${command}" th:remove="tag">
    <p th:if="${#fields.hasErrors('global')}" th:errors="*{global}">
        Incorrect date
    </p>
</div>
<input type="text" th:field="${command.stockNumber}" />
<select th:field="*{command.startYear}">
    <option value="" th:each="year : ${modelYears}" th:value="${year}"
            th:text="${year}"></option>
</select>
</form>

.. Where "command" is the name of the form bean in the controller.

This thread helped me figure it out.

You should be able to access it outside the form or without `th:object="${command}"` by using the syntax `th:errors="${command.global}"`. See [http://www.thymeleaf.org/doc/tutorials/2.1/thymeleafspring.html#displaying-errors-outside-forms] — phn, Oct 04 '16 at 11:51

Spring Thyme Leaf checking for global errors results in NPE

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