I am trying to understand architecture of Spring MVC. However, I am completely
confused by behavior of @SessionAttributes.
Please look at SampleController below , it is handling post method by SuperForm class. In fact, just field of SuperForm class is only binding as I expected.
However, After I put @SessionAttributes in Controller, handling method is binding as SubAForm. Can anybody explain me what happened in this binding.
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@Controller
@SessionAttributes("form")
@RequestMapping(value = "/sample")
public class SampleController {
@RequestMapping(method = RequestMethod.GET)
public String getCreateForm(Model model) {
model.addAttribute("form", new SubAForm());
return "sample/input";
}
@RequestMapping(method = RequestMethod.POST)
public String register(@ModelAttribute("form") SuperForm form, Model model) {
return "sample/input";
}
}
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public class SuperForm {
private Long superId;
public Long getSuperId() {
return superId;
}
public void setSuperId(Long superId) {
this.superId = superId;
}
}
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public class SubAForm extends SuperForm {
private Long subAId;
public Long getSubAId() {
return subAId;
}
public void setSubAId(Long subAId) {
this.subAId = subAId;
}
}
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<form:form modelAttribute="form" method="post">
<fieldset>
<legend>SUPER FIELD</legend>
<p>
SUPER ID:<form:input path="superId" />
</p>
</fieldset>
<fieldset>
<legend>SUB A FIELD</legend>
<p>
SUB A ID:<form:input path="subAId" />
</p>
</fieldset>
<p>
<input type="submit" value="register" />
</p>
</form:form>
