Problem Statement
Jsp
<s:a href="newUser.action" > New User SignIn</s:a>
Struts.xml
<action name="*User" method="{1}" class="action.NewUser">
<result name="populate">/jsp/registerUser.jsp</result>
<result name="success">/jsp/success.jsp</result>
</action>
Action Class has the method
populate(){
}
I am wanting to use the Dynamic Method Invocation facility of STRUTS2. In general the framework substitutes the * word into the method attribute of struts.xml file.
Is there a way in which I can use a different method name. In my case the framework is attaching the method name new() to the struts.xml file but I have a method called populate() in my action class.
You can try to use Preparable interface and Prepare interceptor for this. If your Action class implements Preparable and provides one method called prepare(), it will be always called before executing any action methods.
There is no way to call populate method on newUser.action. You have to call only populateUser.action to call populate method.
Related
I found in a struts project this action mapping:
<action name="action" class="MyClass" method="add">
<result name="success">/jsp/test.jsp</result>
</action>
And in MyClass there is no method name ="add" but there is a method "onAdd"
I wanna know if struts know the name of the method in this case or its an error ?
because I found this in much actionmapping in this project;
Thanks for your help;
Server will throw exception there is no method MyClass.add().
For more details you can look struts2 documentation Action Method
Because when you are mapping action into the staruts.xml then you have to specify the particular class and method and if you are not specifying that method then by Default it will call Execute() method. so now try this and that will call the particular class.
<action name="actionname" class="package.class" method="methodname">
<result name="success">/folder/xyz.jsp</result>
</action>
that way it will work.
Form field is not automatically getting populated for below scenario
public class EmployeeAction extends ActionSupport implements ModelDriven{
private Employee employee=new Employee();
public Object getModel() {
return employee;
}
public String execute() throws Exception {
employee=employeeService.findById(employee.getId());
return super.execute();
}
}
the problem is new employee object but form is expecting old object reference , so manual mapping is working fine,
public String execute() throws Exception {
BeanUtils.copyProperties(employee,employeeService.findById(employee.getId()));
return super.execute();
}
how to avoid this object(new/old) reference problem
Employee.jsp
<s:form action="saveemployee" method="post">
<s:hidden name="id"></s:hidden>
<s:textfield name="name" label="Name" />
<s:textfield name="age" label="Age"></s:textfield>
<s:radio name="gender" label="Gender" list="%{staticMasterMap.gender}" listKey="key" listValue="value" ></s:radio>
<s:label value="DOB"></s:label><fw:datepicker name="dob" id="dob" changeMonth="true" changeYear="true" format="dd/mm/yy" yearRange="1900:2010"></fw:datepicker>
<s:textarea name="address" label="Address"></s:textarea>
<s:submit label="Save"></s:submit>
<s:reset label="Reset"></s:reset>
</s:form>
Struts.xml
<package name="fw" extends="struts-default" namespace="/">
<action name="saveemployee" class="com.example.employee.action.EmployeeAction"
method="save">
<result name="input" type="tiles">employee</result>
<result name="success" type="tiles">employee</result>
</action>
<action name="findemployee" class="com.example.employee.action.EmployeeAction" method="findById">
<result name="success" type="tiles">employee</result>
<result name="input" type="tiles">employee</result>
</action>
</package>
I have not much worked with Struts2 Model Driven Interface and can not recommend what best can be done in your case, but if i am right this is one of the pitfalls of using the Model Driven Interface.
In your case by the time the execute() method has been invoked S2 already has obtained a reference to your Model object which it will use for this particular request cycle. This means you're changing the reference inside your execute method using
employee=employeeService.findById(9l);
but still the framework has reference to the old model object. Since S2 gets the reference using the getter method it has no information what you are doing inside execute method and which is the cause of your data inconsistency.
Honestly i am not sure about any solution for this use-case and will go for a simple Object backed property approach.
Hope some one can provide a workaround if my inputs are correct.
I think the problem is simpler. By default, Struts 2 actions are instanced in each request (also written as having a scope of a request).
When you find a certain Employee an instance of EmployeeAction is created and used to populate the form.
When you press the "Save" button, a new instance of EmployeeAction is created with a new (empty) Employee instance.
You could verify if this is the case by having a constructor log something or using a debugger.
Solving this could be done by saving information to the Session (the employee id, for example) and verifying this data to create a new Employee instead.
Other option is to change the ObjectFactory of Struts 2 to something like Spring.
References: I've used Struts2 with and without Spring and tried to find some official reference. Struts 2 documentation is not clear about the instance creation in the request cycle but the documentation for the Spring plugin of Struts 2 says
Spring 2's bean scope feature can be used to scope an Action instance
to the session, application, or a custom scope, providing advanced
customization above the default per-request scoping.
How can I pass an attribute into my struts2 java action that tells me whether the action was called from one URL path / action mapping vs another?
I figured I could put something in the struts.xml for two action mappings but use the same java action and just pass in a flag into the action.
You'll want to use the <param/> tag. I do this frequently for actions that handle both adding and editing an entity, as the fields, validations, and whatnot are virtually identical. Here's an example of that.
struts.xml
<action name="users/add" class="AddEditUserAction">
<param name="edit">false</param>
<result name="input">/WEB-INF/jsp/addEditUser.jsp</result>
</action>
<action name="users/{username}/edit" class="AddEditUserAction">
<param name="edit">true</param>
<result name="input">/WEB-INF/jsp/addEditUser.jsp</result>
</action>
The Action
public class AddEditUserAction {
private boolean isEdit;
// this is called by the struts.xml to set the value
public void setEdit(final boolean edit) {
isEdit = edit;
}
}
In order for this to work, you need the static parameters interceptor in your stack (it's included by default).
I question the design.
I'd handle it by specifying a method in the action configuration for one or both mappings.
The method(s) would set a flag in the action and call the "guts" of the action, which would query the flag value, and proceed accordingly.
How would I execute a method with an argument in my model based on the URL? Ie, http://server/MyAction_Arg.action maps to MyClass.MyMethod(Arg)? I tried this:
<action name="MyAction_*" method="MyMethod({1})" class="example.MyClass">
<result>page.jsp</result>
</action>
but I get java.lang.NoSuchMethodException at runtime
In struts2 you can accomplish this like this:
server/myaction.action?arg=value
And in the MyClass action class you can declare a variable variable named arg with getter and setter. In the MyMethod() method you have access to the value of arg via the getArg() method.
In my TestClass action I am setting an action error using addActionError method. I have an action defined in the struts.xml as following
<action name="TestAction" class="TestClass">
<result name="input">/jsp/test.jsp</result>
<result name="error" type="httpheader">
<param name="error">409</param>
<param name="errorMessage">${SOME-EXPRESSION}</param>
</result>
</action>
The intent is to have the error message display whatever was added using addActionError. According to the org.apache.struts2.dispatcher.HttpHeaderResult documentation, I should be able to use Ognl expressions within errorMessage parameter.
So, is it possible to put something in place of ${SOME-EXPRESSION} that will reference actionerror in this scenario.(I tried ${actionerror} but it didn't work)
I know that I can have a workaround by declaring my own field (for example "errorText") in the action class and using that insteda of addActionError referencing it using ${errorText} inside the param tags. But before I go that route, want to make sure that's the only way.
Action errors are stored in a list, so you'll have to show something like ${actionErrors[0]}. But keep in mind this way it will only show your first added error, not all those you have included using addActionError.