When I bind data with custom controller, the following code works well.
public class searchContactCtrl {
String searchText;
public String getSearchText(){
return searchText;
}
public void setSearchText(String s ){
searchText =s;
}
}
but if I changed getter method of "searchText" as below, an error was occured.
public class searchContactCtrl {
public String searchText{get;}
public void setSearchText(String s ){
searchText =s;
}
}
Error message:
Compile Error: member variable not visible for assignment
Why is this happening?
You will need to define a private setter for the searchText property. E.g.
public class searchContactCtrl {
public String searchText {
get;
private set;
}
public void setSearchText(String s) {
searchText = s;
}
}
Or you could just remove the private modifier and directly set searchText without the setSearchText method.
Related
I'm working on a GUI application in WPF/MVVM. Let's say i have a Model class which is populated deserializing a (third-party) XML file
class Person
{
public string Name { get; set; }
public string Address { get; set; }
public string ReservationId { get; set; }
}
and a ViewModel which exposes to its View a lot of properties and commands to manipulate the Model, in this case strings (such as ReservationId):
class StringManipulatorViewModel
{
string modelString; //here's the problem
public StringManipulatorViewModel(string modelString)
{
this.modelString = modelString;
}
//Stuff to let the view manipulate the string
}
StringManipulatorViewModel is highly reusable and it is used by a lot of ViewModels, e.g.
class PersonViewModel
{
Person model;
public StringManipulatorViewModel ReservationManipulatorVM; //aggregated ViewModel
public StringManipulatorViewModel AddressManipulatorVM; //aggregated ViewModel
public PersonViewModel(Person model)
{
this.model = model;
ReservationManipulatorVM = new StringManipulatorViewModel(model.ReservationId); //here's the problem
AddressManipulatorVM = new StringManipulatorViewModel(model.Address); //here's the problem
}
}
Obviously passing the string as "model" to the ViewModel isn't effective, and C# doesn't seem to allow string references as fields.
What is the best/right way to let member ViewModels manipulate the Model when dealing with string types?
Thank you
Your problem is that you are trying to reference a property, not a string field.
But you can pass a delegate to the setter of the property.
If you also change the modelString field to a property, you can call this delegate automatically when the string is changed.
class StringManipulatorViewModel
{
private string modelString
{
get { return _modelString; }
set { _modelString = value; if (SetModelString != null) SetModelString(value); }
}
private string _modelString;
Action<string> SetModelString;
public StringManipulatorViewModel(string initialValue, Action<string> setModelString)
{
this.modelString = initialValue;
SetModelString = setModelString;
}
//Stuff to let the view manipulate the string
}
You initiate the StringManipulatorViewModel in PersonViewModel like this:
ReservationManipulatorVM = new StringManipulatorViewModel(model.ReservationId, value => model.ReservationId = value); //here's the problem
Here are some other ideas when you want to pass a property.
Passing properties by reference in C#
I can't think of a "right" way to manipulate the string as a reference inside the StringManipulatorViewModel, once you pass the string as a value it has nothing to do with the model.
But a way to legitimately change the model string value whenever the StringManipulatorViewModel manipulates it, is by raising an Event in the view model when it manipulates the string and then add an event handler to update the model with the new value:
class StringManipulatorViewModel
{
string modelString;
public event EventHandler<string> StringManipulated;
public StringManipulatorViewModel(string modelString)
{
this.modelString = modelString;
}
public ManipulateString()
{
// Manipulate the string
StringManipulated?.Invoke(this, modelString);
}
}
And in the PersonViewModel constructor:
class PersonViewModel
{
Person model;
public StringManipulatorViewModel ReservationManipulatorVM;
public StringManipulatorViewModel AddressManipulatorVM;
public PersonViewModel(Person model)
{
this.model = model;
ReservationManipulatorVM = new StringManipulatorViewModel(model.ReservationId);
AddressManipulatorVM = new StringManipulatorViewModel(model.Address);
ReservationManipulatorVM.StringManipulated += (sender, e) => model.ReservationId = e;
AddressManipulatorVM.StringManipulated += (sender, e) => model.Address = e;
}
}
I want to create a keyword search referring to "UserName__c" api on Salesforce Apex class.
compile error Unexpected token 'UserName__c'.
public with sharing class AccountListCon {
static List<String> TARGET_FIELDS = new List<String>{
'Name'
,'UserName__c'
,'CompanyName__c'
};
public SearchCondition condition{ get;set; }
public String UserName__c results { get;set; }
public String sortingField { get;set; }
public void init(){
this.condition = new SearchCondition();
this.results = new String UserName__c();
}
public PageReference clear(){
init();
return null;
}
There is no such type String UserName__c. It's not entirely clear what you want to do here, but I suspect you intend just to declare a String variable. The fact that you're looking for values in some field whose API name is UserName__c is not relevant to the type system
public String UserName__c results { get;set; } is wrong. Is this supposed to be just
public String results { get;set; } ?
Thanks in advance!
How should I use ObservesCanExecute in the DelegateCommand of PRISM 6?
public partial class UserAccountsViewModel: INotifyPropertyChanged
{
public DelegateCommand InsertCommand { get; private set; }
public DelegateCommand UpdateCommand { get; private set; }
public DelegateCommand DeleteCommand { get; private set; }
public UserAccount SelectedUserAccount
{
get;
set
{
//notify property changed stuff
}
}
public UserAccountsViewModel()
{
InitCommands();
}
private void InitCommands()
{
InsertCommand = new DelegateCommand(Insert, CanInsert);
UpdateCommand = new DelegateCommand(Update,CanUpdate).ObservesCanExecute(); // ???
DeleteCommand = new DelegateCommand(Delete,CanDelete);
}
//----------------------------------------------------------
private void Update()
{
//...
}
private bool CanUpdate()
{
return SelectedUserAccount != null;
}
//.....
}
Unfortunatelly, I'm not familiar with expressions in c#. Also, I thought this would be helpful to others.
ObservesCanExecute() works “mostly like” the canExecuteMethod parameter of DelegateCommand(Action executeMethod, Func<bool> canExecuteMethod).
However, if you have a boolean property instead of a method, you don't need to define a canExecuteMethod with ObservesCanExecute.
In your example, suppose that CanUpdate is not a method, just suppose that it's a boolean property.
Then you can change the code to ObservesCanExecute(() => CanUpdate) and the DelegateCommand will execute only if the CanUpdate boolean property evaluates to true (no need to define a method).
ObservesCanExecute is like a “shortcut” over a property instead of having to define a method and having passing it to the canExecuteMethod parameter of the DelegateCommand constructor.
I am trying to access a custom attribute applied to a method within a castle interceptor, but method Attribute.GetCustomAttribute() return null.
public class MyIntecept : Castle.DynamicProxy.IInterceptor
{
public void Intercept(IInvocation invocation)
{
// myAttr is null.
var myAttr = (MyAttribute)Attribute.GetCustomAttribute(
invocation.Method, typeof(MyAttribute));
}
}
[AttributeUsage(AttributeTargets.All, Inherited = true, AllowMultiple = true)]
public class MyAttribute : Attribute
{
readonly string _value;
public MyAttribute(string value)
{
this._value = value;
}
public string Value
{
get { return this._value; }
}
}
public interface IMyInterface
{
void Do();
}
public class MyClass : IMyInterface
{
[MyAttribute("MyValue")]
public void Do()
{
Console.WriteLine("Do");
}
}
How can i get 'MyAttribute'?
P.S. I'am using Castle.Core 3.3.3
Put the attribute "MyAttribute" on the method inside the interface and not inside the class
How do I obtain values of an array that is located inside a java object in a jsp page?
I have set an object attribute so that in the jsp page I can call the object like so
${obj.property}
My question is how would I obtain property String [] example from Object obj?
<c:forEach var="prop" items="${obj.example}">
<td>${prop}</td>
</c:forEach>
I get Errors that tell me the class obj.Obj does not have the property property 'example'
and obviously I don't get the data out.
Actual errors:
org.apache.jasper.JasperException: javax.el.PropertyNotFoundException: The class 'roommate.Roommate' does not have the property 'favProfessors'.
javax.el.PropertyNotFoundException: The class 'roommate.Roommate' does not have the property 'favProfessors'
And my actual class:
package roommate;
public class Roommate{
public String firstname;
public String lastname;
public String gender;
public String place;
public String[] favProfessors;
public Roommate(String fname, String lname, String roommateGender, String hangout,String[] professors) {
firstname= fname;
lastname= lname;
gender= roommateGender;
place= hangout;
favProfessors= professors;
}
public String getFirstname()
{
return firstname;
}
public void setFirstname(String newFirstname)
{
this.firstname = newFirstname;
}
public String getLastname()
{
return lastname;
}
public void setLastname(String newLastname)
{
this.lastname = newLastname;
}
public String getGender()
{
return gender;
}
public void setGender(String newGender)
{
this.gender = newGender;
}
public String getHangout()
{
return place;
}
public void setHangout(String newPlace)
{
this.place = newPlace;
}
public String[] getProfessors()
{
return favProfessors;
}
public void setProfessors(final String[] newfavProfessors)
{
this.favProfessors = newfavProfessors;
}
public void addRoommate(String fname, String lname, String roommateGender, String hangout,String[] professors)
{
}
}
I create the object in my servlet as well ass the Atrribute
String [] profArray = request.getParameterValues("professor");
Roommate roommate= new Roommate(
session.getAttribute("fname").toString(),
session.getAttribute("lname").toString(),
session.getAttribute("gender").toString(),
session.getAttribute("hangout").toString(),
profArray);
session.setAttribute("roommate",roommate);
I asked this earlier but did not receive a clear answer. I think my issue is in pulling the data out in the jsp alone in my forEach that I mentioned at the top
javax.el.PropertyNotFoundException: The class 'roommate.Roommate' does not have the property 'favProfessors'
Java is right. You do not have a getFavProfessors() method in that class. It's instead the following:
public String[] getProfessors()
{
return favProfessors;
}
You have 2 options: use ${roommate.professors} instead, or fix the getter method name to be getFavProfessors().
In contrary to what most starters think, EL does not access private properties directly. EL just calls the public getter/setter methods according the Javabeans specification. The real private property behind it can have a completely different name or even not exist at all.