Spring Thymeleaf-th：field中的条件表达式

Question

条件表达式（文档）：

<tr th:class="${row.even}? 'even' : 'odd'"> 

// This works fine.
<input type="text" th:value="${object.covered} ? 'yes' : 'no'" />

// This on the other hand, generates the error mentioned earlier.
// Which does make sense, cause it would otherwise generate invalid attributes.
<input type="text" th:field="${object.covered} ? 'yes' : 'no'" />

// Combining the two does not work.
<input type="text" th:field="${object.covered}" th:value="${object.covered} ? 'yes' : 'no'" />

// Ultimateley, what I want to achieve is something like this.
<input type="text" th:field="${person.age}" 
       th:value="${person.age} le 0 ? null : ${person.age}" 
       placeholder="age" />

（Thymeleaf 2.1.5和Spring Boot 1.4.2)

Answer 1

Thymeleafth:field生成3个html属性id、name和value。

对于您的情况，当年龄小于零时，不使用th:field，而是使用id、name和placeholder，如下所示

<input th:if="${person.age > 0}" type="text" th:field="${person.age}" />
<input th:if="${person.age <= 0}" type="text" id="person.age" name="person.age" placeholder="age"/>