[英]Creating ArrayList through Form submitting ( Thymeleaf + Spring MVC )
i wanted to know, how Lists are getting binded in Spring...and how to access them in Thymeleaf. 我想知道,列表是如何在春季绑定的……以及如何在Thymeleaf中访问它们。 With and without WrapperClass How could achieve adding single / multiple objects through an form to an ArrayList or normal Array..
使用和不使用WrapperClass如何实现通过表单将单个/多个对象添加到ArrayList或普通Array。
I would be very thankful for an explanation. 我非常感谢您的解释。
Thats what i have tried: Form 那就是我尝试过的:表格
<form action="#" th:action="@{/tests}" th:object="${features}" method="post">
<input type="text" th:field="*{featureArrayList[0].name}"/>
<input type="text" th:field="*{featureArrayList[1].name}"/>
<p><input type="submit" value="Submit" /> <input type="reset" value="Reset" /></p>
</form>
Wrapper Class 包装类
ArrayList<Feature> featureArrayList = new ArrayList<Feature>();
public FeatureWrapper() {
}
public ArrayList<Feature> getFeatureArrayList() {
return featureArrayList;
}
public void setFeatureArrayList(ArrayList<Feature> featureArrayList) {
this.featureArrayList = featureArrayList;
}
Model: 模型:
private String name;
public Feature(String name) {
this.name = name;
}
public Feature() {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
Controller 调节器
@GetMapping("/tests")
public String showForm(Model model)
{
FeatureWrapper featureWrapper = new FeatureWrapper();
model.addAttribute("features", featureWrapper);
return "Feature";
}
@PostMapping("/tests")
public String proceedForm(@ModelAttribute("features") FeatureWrapper features,Model model)
{
for(Feature feature: features.getFeatureArrayList())
{
System.out.println(feature.getName());
System.out.println(features.getFeatureArrayList().size());
}
return "Feature";
}
Edit1: Now its working with an Wrapper Class and using static Indexes... How would i achieve this without a wrapper class , i read much about the EL expression ${var.index} , but how is this working ? Edit1:现在,它可以与包装类一起使用并使用静态索引...如果没有包装类,我将如何实现这一点,我对EL表达式$ {var.index}有了很多了解,但是它如何工作? And how should i use this to dynamically add my Objects.
以及我应该如何使用它动态添加我的对象。 Edit2: Now im able to add single objects , and multiple objects to the list, but im not using any EL Expression, so i wanted to know when would i need to use something like this:
Edit2:现在,我可以将单个对象和多个对象添加到列表中,但是我不使用任何EL表达式,所以我想知道何时需要使用如下所示的内容:
<div th:each="feature,stat:*{featureArrayList}">
<input id="myInput" type="text" th:field="*{featureArrayList[__${stat.index}__].name}"/>
</div>
As far as I know, you can't bind to a list without a wrapper class (as stated in comments). 据我所知,没有包装类就无法绑定到列表(如注释中所述)。
In normal Thymeleaf expressions, you can directly use variables as indexes. 在正常的Thymeleaf表达式中,您可以直接使用变量作为索引。 Expressions like this for example:
例如这样的表达式:
<th:block th:with="i=0"> <span th:text="${array[i]}" /> </th:block>
However, th:field expressions are different. 但是,th:field表达式是不同的。 If you read the section on dynamic fields :
如果您阅读有关动态字段的部分:
The problem is that Spring EL does not evaluate variables inside array index brackets, so when executing the above expression we would obtain an error telling us that
rows[rowStat.index]
(instead ofrows[0]
,rows[1]
, etc) is not a valid position in the rows collection.问题是Spring EL不会对数组索引括号内的变量求值,因此在执行上述表达式时,我们将得到一个错误,告诉我们
rows[rowStat.index]
(而不是rows[0]
,rows[1]
等)在rows集合中不是有效位置。 That's why preprocessing is needed here.这就是为什么这里需要预处理的原因。
So, when you are using th:field
to bind inputs to arrays, you must use preprocessing which is why you see expressions like this: 因此,当您使用
th:field
将输入绑定到数组时,必须使用预处理,这就是为什么看到以下表达式的原因:
<input type="text" th:field="*{featureArrayList[__${stat.index}__].name}"/>
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