在Spring MVC控制器中发现加载了Ajax的动态下拉列表为null [英] Dynamic drop down loaded with ajax is found as null in spring mvc controller
问题描述
我已经通过 ajax 调用动态加载了一个下拉列表，但是问题是我无法在 controller 中访问它.在控制器中，动态加载的下拉列表为 null ！
I've dynamically loaded a dropdown with ajax call but the problem is I can't access it in controller. the dynamically loaded dropdown is found as null in controller!
JSP代码:
<body>
<c:url var="updateUrl" value="${actionPath}"/>
<form:form method="post" action="${updateUrl}" commandName="complaintDetail">
<table>
<tr>
<td><form:label path="complaintCategory">Category</form:label></td>
<td>
<form:select path="complaintCategory">
<form:option value="NONE" label="--- Select ---" />
<form:options items="${categoryList}"/>
</form:select>
</td>
</tr>
<tr>
<td><form:label path="complaintReasonDetail">Reason</form:label></td>
<td>
<form:select path="complaintReasonDetail">
<form:option value="NONE" label="--- Select ---" />
<form:options items="${reasonList}" />
</form:select>
</td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="${submitString}">
</td>
</tr>
</table>
</form:form>
</body>
JS代码:
$('#complaintCategory').change(
function(){
var findReasonsURL = '/Vela-web-client/complaint/getReason/' + $(this).val() + '/GENERAL.htm';
//alert($(this).val());
$.getJSON(findReasonsURL, {},
function(data) {
var html = '<option value="">--- Select ---</option>';
var len = data.length;
$.each(data, function(i, obj){
html += '<option value="' + obj.idNr + '">' + obj.complaintReasonSt + '</option>';
});
$('#complaintReasonDetail').html(html);
});
});
对于此ajax调用，相应的控制器代码:
@RequestMapping(value = "/complaint/getReason/{category}/{rType}", method = RequestMethod.GET)
public @ResponseBody
List<ComplaintReasonDetail> getReason(
@PathVariable(value = "category") String category,
@PathVariable(value = "rType") String rType)
{
List<ComplaintReasonDetail> complaintReasonDetails;
ComplaintCategory complaintCategory = ComplaintCategory.valueOf(category);
ReasonType reasonType = ReasonType.valueOf(rType);
try
{
complaintReasonDetails = ComplaintReasonHandler.getComplaintReasonAdvanceSearchResult("", false, complaintCategory, true, reasonType, true, BigInteger.ONE);
System.out.println("reason list count = " + complaintReasonDetails.size());
return complaintReasonDetails;
}
}
到目前为止，一切正常！
Up to this, everything works fine!
我提交表单时出现问题.我在控制器代码中以 null 的形式获得了 complaintReasonDetail .
The problem occurs when I submit the form. I get complaintReasonDetail as null in controller code.
控制器代码:
@RequestMapping(value = "/complaint/doadd/addnew", method = RequestMethod.POST)
public String addCompliant(@RequestBody @ModelAttribute("complaintDetail") ComplaintDetail complaintDetail, BindingResult result, Model model)
{
System.out.println("category = "+complaintDetail.getComplaintCategory()); // OK
System.out.println("reason = "+complaintDetail.getComplaintReasonDetail()); // print null ???
}
这是一个很长的问题，但是要弄清楚，我认为这是必要的.
It's a bit long question, but to make it clear, i think it is necessary.
那么，我到底想念什么?
So, what am I missing actually?
推荐答案
您可以通过带有onchange事件的select调用ajax，例如以下代码:
You can call ajax from select with onchange event like code below:
function onChangeAjaxMain()
{
var name = $('#state').val();
$.ajax({
type: "POST",
url : 'mainAjax',
data: ({
nameOfCategory: name
}),
success : function(data) {
$('#city').html(data);
}
});
}
在jsp中使用form:spring格式:
in jsp use form:spring format:
<form:select name="state" id="state" onclick="onChangeAjaxMain()" path="state">
<form:option value="1">blah</form:option>
<form:option value="2">blah</form:option>
</form:select>
<br>
<form:select id="city" path="city">
<form:option value="NONE">City</form:option>
</form:select>
最终在控制器中:
@RequestMapping(value = "/mainAjax", method = RequestMethod.POST)
public @ResponseBody
String mainAjax(@RequestParam("state") String state){
String cities= "<option value=\"\">City</option>";
ArrayList<City> citySet = /*fill list respect to state*/
for(City city : citySet){
cities+= "<option value=\""+city.getName+"\">"+city.getName+"</option>";
}
cities+= "</option>";
return cities;
在maven中添加:jackson-core和jackson-databind.我使用2.6.3版本，并在1.5.3版本中添加jackson-mapper-asl
In maven add: jackson-core and jackson-databind. I use 2.6.3 version and also add jackson-mapper-asl with 1.5.3 version
希望对您有所帮助！
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