Apologies in advance for the amateur nature of this question.
I am developing a Windows Forms Application and I am wondering how can I implement a method in a Baseform which then has to be implemented in all forms which inherit from this?
For example I have this as my baseform:
public partial class Baseform : RadForm
{
public Baseform()
{
InitializeComponent();
}
}
How do I then add a method to this class, so that every form that I create like this:
public partial class CustomForm : Baseform
{
public CustomForm()
{
InitializeComponent();
}
}
has to declare this method?
Any help / direction to other resources is appreciated.
Thanks.
Forms are just classes, and you use the C# inheritance rules to play with it. So if you want state the children implement a function declare the base abstract with one ( or possibly more ) abstract methods.
Related
I found the following use of a wrapper class, and was wondering if it is a good practice or whether its just duplication of code for no reason.
//Class:
public class SomeClass{
public Integer someInt;
public String someString;
}
//Callout Class:
public class CalloutClass{
public SomeClass someMethod(){
//...code to do a callout to an api
SomeClass someClassObj = (SomeClass)JSON.Deserialize(APIResponse.getBody(), SomeClass.class);
return someClassObj;
}
}
//Controller:
public class SomeController {
public SomeController(){
someClassObj = calloutClassObj.someMethod();
SomeWrapper wrapperObj = new SomeWrapper();
for(SomeClass iterObj : someClassObj){
wrapperObj.someWrapperInt = iterObj.someInt;
wrapperObj.someWrapperString = iterObj.someString;
}
}
public class someWrapper{
public Integer someWrapperInt{get;set;}
public String someWrapperString{get;set;}
}
}
The wrapper class "someWrapper" could be eliminated if we just use getters and setters ({get;set;}) in "SomeClass."
Could anyone explain if there could be a reason for following this procedure?
Thanks,
James
My assumption (because, code in controller is extra pseudo) is
SomeClass is a business entity, purpose of which is to store/work with business data. By work I mean using it's values to display it (using wrapper in controller), to calculate smth in other entities or build reports... Such kind of object should be as lightweight as possible. You usually iterate through them. You don't need any methods in such kind of objects. Exception is constructor with parameter(s). You might want to have SomeObject__c as parameter or someWrapper.
someWrapper is a entity to display business entity. As for wrapper classes in controllers. Imagine, that when you display entity on edit page and enter a value for someWrapperInt property, you want to update someWrapperString property (or you can just put validation there, for example, checking if it is really Integer). Usually, as for business entity, you don't want such kind of functionality. But when user create or edit it, you may want smth like this.
I am working a project in gui builder..As my project is growing bigger and bigger, i find it hard to search a particular forms and methods all in a statemachine class. so i wanted to create a separate class for each form. but since the gui builder create the methods automatically in statemachine which extends statemachineBase class. how can i use separate class for separate gui forms so that they automatically create methods in the designated class. for instance when i click before show event of form named "NextPage", the gui builder automatically create beforeNextPage method in NextPage class instead of statemachine. I did the followings but lost in the process..
NextPage.class
public class NextPage extends StateMachine {
private ArrayList<Map<String, Object>> mData;
private ArrayList<Map<String, Object>> moreData;
public NextPage(String resFile) {
super(resFile);
}
#Override
public void beforeNextPage(Form f) {
//.........
}
}
Forms generated by GUI Builder cannot be separated from StateMachineBase into different Classes.
What I do personally is create a form in GUI to get the right Look and Feel and then create a replica of that form in code, then delete the one on GUI Builder once I'm satisfied with the code version. It makes my projects well organized and easy to debug.
BeforeShow() would be handle while the form class is loading and to do anything in PostShow(), just do this:
this.addShowListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
removeShowListener(this);
//Your postShow() codes here.
revalidate();
}
});
Forms created in code are light-weight and more customizable than GUI forms.
Is there any way that I use data annotation as the source of validation in WPF? I want to be able to define a class such as:
class myData
{
[Required]
[MaxLength(50)]
public string Name{get;set;}
}
And then bind it to a field in a view and the wpf validate that user enter some value for this field and also make sure that its length is not greater than 50. I know that I can write a validator for this, but then if I change the maxLength to say 60, then I need to change it in validator and I don't want to have changes in different places.
You need to create a "metadata" definition of the class. You'll need something like this:
[MetadataTypeAttribute(typeof(MyClass.MyClassMetadata))]
public partial class MyClass
{
internal sealed class MyClassMetadata
{
// Metadata classes are not meant to be instantiated.
private MyClassMetadata()
{
}
[Required]
[MaxLength(50)]
public string Name{ get; set; }
}
}
This extends the class with the necessary meta data to support the validation.
Since this question is still left unanswered and I came across it while answering another question that was looking for the same thing, I would share the solution of that question over here too.
The Microsoft TechNet article "Data Validation in MVVM" is a very clean and thorough implementation of using Data Annotations for validation in WPF. I read through the solution myself and would recommend it to others.
I have two viewmodel classes called ChangePwdViewModel.cs and ExpiringPwdViewModel.cs.
ChangPwd.xaml binds to ChangePwdViewModel and ExpiringPwd.xaml binds to ExpiringPwdViewModel.
Both have the property as below.
private string _message;
public string Message
{
get { return _message; }
set { _message = value; OnPropertyChanged("Message"); }
}
In each class, there's a function called ValidatePwd() to validate the new password.
In this function, Message property is updated.
Eg.
if (IsAlphaNumeric(this.NewPassword) == false || IsAlphaNumeric(this.CfmPassword) == false)
{
this.Message = "Invalid new password, only characters and numbers are accepted, password must contain at least one character and one number";
this.ResetPasswordFields();
return false;
}
I want to create a common class to write this function and used by two viewmodel. But, How can I update the Message Property of the viewmodels from this class?
How about putting it in a base class:
class ViewModelBase
{
private string _message;
public string Message
{
get { return _message; }
set { _message = value; OnPropertyChanged("Message"); }
}
public bool VerifyPassword(string newPassword)
{
....
}
}
class ChangePwdViewModel : ViewModelBase
{
}
class ExpiringPwdViewModel : ViewModelBase
{
}
Update:
If you can't use a base class because your view models already have a base class then you could use an interface as suggested by others. However this means that you will still have to implement the interface in all your view model classes so you don't gain that much in terms of avoiding multiple implementations (except that you have a contract for your view models then which is usually a good thing to have).
You can achieve some kind of "multiple inheritance" in C# by using a tool like Dynamic Proxy which allows you to create mixins. So you could implement the Message property and password verification in one class and then create a mixin proxy which merges the view model with that implementation. It's not as nice as you will have to create all your view model instances via the proxy generator but it can be made to work. Have a look at this tutorial if it sounds like an option for you.
You could have the two ViewModel classes implement a common interface, say IMessage that implemented a single property - Message.
Then your common class or a function would take a parameter of type IMessage that it could use to update the message.
I would suggest to avoid base classes (could cause potential design issues in future) in such cases, I would rather suggest to pass through constructor an algorithm of validation, smth like this:
public class MyViewModel
{
public MyViewModel(Func<bool> validationAlgorithm)
{
// ... save function to use later for a validation
}
}
i have a winforms project, and i created a class on assembly A that inherits from System.Windows.Forms.Form to serve as a base class for various forms on my project, the base class is something like:
public partial class DataForm<T> : Form where T : class
{
T currentRecord;
protected T CurrentRecord
{
get
{
return currentRecord;
}
set
{
currentRecord = value;
CurrentRecordChanged();
}
}
}
Now, when i create a form on assembly B that inherits from my DataForm the designer won't load, but if i compile it the app runs fine.
The form looks like:
public partial class SomeTableWindow : DataForm<SomeTable>
{
public SomeTableWindow ()
{
InitializeComponent();
}
}
The error I'm getting is:
The designer could not be shown for this file because none of the classes within it can be designed.
The designer inspected the following classes in the file: CultivosWindow --- The base
class 'TripleH.Erp.Controls.DataForm' could not be loaded. Ensure the assembly has
been referenced and that all projects have been built.
Instances of this error (1)
1. Hide Call Stack
at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager)
at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host)
Is this a bug on the designer?, Am I doing something wrong? Is there some workaround this?
Thank you for your help
It's a known limitation. Basically you can work around this by declaring another class that inherits from the generic class.
For instance:
class Generic<T> : UserControl
{
}
then
class GenericInt : Generic<int> { }
then use GenericInt instead of Generic. SUcks I know.