如何使用 thymeleaf 将迭代索引放入数组索引中？

Question

I am trying to iterate over list with keeping track of iteration and I want to place iteration index into array index of that list:

What I tried:

<tr th:each="experience, iter : *{experiences}">
    <td>Experience name:</td>
    <td><input type="text" th:field="*{experiences[iter.index]}" value="${experience.name}">
</tr>

Here I get NumberFormatException. So I tried to use $, because I think that iter is a variable:

<tr th:each="experience, iter : *{experiences}">
    <td>Experience name:</td>
    <td><input type="text" th:field="*{experiences[${iter.index}]}" value="${experience.name}">
</tr>

Here, ${iter.index} is not evaluated, so我会发现$ {iter.index}不是数字的错误（再次numberformateXception）。

Answer 1

您可以使用2个下划线使用iter.index。

<tr th:each="experience, iter : *{experiences}">
    <td>Experience name:</td>
    <td><input type="text" th:field="*{experiences[__${iter.index}__]}" />
</tr>

__ $ {...} __语法是一种预处理表达式，它是一个内部表达式，在实际评估整个表达式之前进行评估。 https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf#预处理