I want to map a given XML in object form. The XML includes e.g. values like a file path. A typical path consists of an xml-attribute for the folder-path and a file-name. The pattern should give me the opportunity to load and save object at any time. I don't want to put the file path always manually together or separate them. (I don't want to change the original serialized-object (like "katalog","kovkatalog",) because it is automatically generated.)
I think inheritance could solve my problem and improve the overviewability of my code (or should I use an other wrapper?). Is something against the approach? Are there any better approaches?
When deserializing, the following error is always returned:
"InvalidOperationException: http://example.net/V3.0/Schema'> is not expected."
Does anyone have a solution for how I can extend inheritance with additional methods?
VB.NET-CODE:
Namespace abc
Public Class Main
Public Sub New()
Dim des As New unifa_katalog
des = Deserialisieren(Of unifa_katalog)("<PATH_TO_FILE>\katalog.xml")
End Sub
Private Function Deserialisieren(Of T)(strSpeicherOrt As String) As T
Dim serializer As New XmlSerializer(GetType(T))
Dim deserialized As T = Nothing
Using file = System.IO.File.OpenRead(strSpeicherOrt)
deserialized = DirectCast(serializer.Deserialize(file), T)
End Using
Return deserialized
End Function
End Class
<XmlRoot("katalog", [Namespace]:="urn:kosxmlns")>
Partial Public Class unifa_katalog
Inherits katalog
Public Sub furtherMethod()
End Sub
End Class
<System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.1432"),
System.SerializableAttribute(),
System.Diagnostics.DebuggerStepThroughAttribute(),
System.ComponentModel.DesignerCategoryAttribute("code"),
System.Xml.Serialization.XmlTypeAttribute(AnonymousType:=True, [Namespace]:="http://example.net/V3.0/Schema"),
System.Xml.Serialization.XmlRootAttribute([Namespace]:="http://example.net/V3.0/Schema", IsNullable:=False)>
Partial Public Class katalog
Inherits kovkatalog
End Class
Partial Public Class kovkatalog
Private verfahrenField As String
Private verfahrensversionField As String
Private katalogversionField As Integer
Private myversionField As String
Public Sub New()
MyBase.New
Me.katalogversionField = 1
End Sub
'''<remarks/>
<System.Xml.Serialization.XmlAttributeAttribute()>
Public Property verfahren() As String
Get
Return Me.verfahrenField
End Get
Set
Me.verfahrenField = Value
End Set
End Property
'''<remarks/>
<System.Xml.Serialization.XmlAttributeAttribute("verfahrens-version")>
Public Property verfahrensversion() As String
Get
Return Me.verfahrensversionField
End Get
Set
Me.verfahrensversionField = Value
End Set
End Property
'''<remarks/>
<System.Xml.Serialization.XmlAttributeAttribute("katalog-version"),
System.ComponentModel.DefaultValueAttribute(1)>
Public Property katalogversion() As Integer
Get
Return Me.katalogversionField
End Get
Set
Me.katalogversionField = Value
End Set
End Property
'''<remarks/>
<System.Xml.Serialization.XmlAttributeAttribute("my-version")>
Public Property myversion() As String
Get
Return Me.myversionField
End Get
Set
Me.myversionField = Value
End Set
End Property
End Class
End Namespace
XMLFILE:
<?xml version="1.0" encoding="UTF-8"?>
<kov:katalog verfahren="kov" my-version="03000200" katalog-version="1" verfahrens-version="06090000" xmlns:kov="http://example.net/V3.0/Schema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
</kov:katalog>
It's not really an inheritance issue, rather a namespace issue. If you use the same namespace, it will deserialize
<XmlRoot("katalog", [Namespace]:="http://example.net/V3.0/Schema")>
Partial Public Class unifa_katalog
Inherits katalog
Public Sub furtherMethod()
End Sub
End Class
Related
So this is how I would design my Lazy class (From this SO):
Public NotInheritable Class MySingleton
Private Shared ReadOnly _instance As New Lazy(Of MySingleton)(Function() New _
MySingleton(), System.Threading.LazyThreadSafetyMode.ExecutionAndPublication)
Private Sub New()
End Sub
Public Shared ReadOnly Property Instance() As MySingleton
Get
Return _instance.Value
End Get
End Property
Private _MyString As String
Public Property MyString As String
Get
Return _MyString
End Get
Set(value As String)
_MyString = value
End Set
End Property
End Class
To access the _MyString value, I do the following:
Dim MyString = MySingleton.Instance.MyString
In fact, I always have to type the ".Instance."
Does it have any disadvantage if I design the Property the following way:
Public Property MyString As String
Get
Return instance._MyString
End Get
Set(value As String)
instance._MyString = value
End Set
End Property
So I can access it without always writing the ".Instance."
Dim MyString = MySingleton.MyString
Yes you can (of course with Public Shared Property), but you are losing some of the benefits from singleton over static classes.
Lets say you have another class MyWorker
Public Class MyWorker
Public Sub Work(instance as MySingleton)
Dim value as String = instance.MyString
' Do something ...
End Sub
End Class
I would not do this. This may not look like a big issue, but on the long run you have a tight coupling in your code base and a hard time mocking your class for unit testing, one of the reasons for using singeltons over static classes in the first place.
I often use this approach, when accessing Singelton values mutiple times:
Dim instance as MySingelton = MySingelton.Value
If instance.MyString = "something" Then
instance.MyString = "something else"
End If
much cleaner approach.
I've created a request class. Here is an abbreviated version of it:
Public Class Request(Of T)
Private _Account As String
Public Property Account() As String
Get
Return _Account
End Get
Set(ByVal value As String)
_Account = value
End Set
End Property
Private _InnerRequest As T
Public Property InnerRequest() As T
Get
Return Me._InnerRequest
End Get
Set(ByVal value As T)
Me._InnerRequest = value
End Set
End Property
End Class
And then I have two other classes that I intend to use with this one - again, abbreviated
Public Class Individual
Public FirstName As String
Public LastName As String
Friend Sub New()
End Sub
End Class
And
Public Class Commercial
Public EntityName As String
Friend Sub New()
End Sub
End Class
Again, both of these are pretty abbreviated. The issue comes in when I attempt to use the properties of individual or commercial:
Dim Req As New Request(Of Individual)()
Req.InnerRequest.FirstName = "Herman" <-- Null Ref Exception
So... how do I get my inner request null ref exception kicked? I tried simply using Me._InnerRequest = New T in the New sub of Request, but no dice. Is there a way to handle this?
Req.InnerRequest must be set to an object instance of Individual first.
Req.InnerRequest = new Individual()
Req.InnerRequest.FirstName = "Herman"
Or create an instance for InnerRequest with the following modifications
Public Class Request(Of T As {New}) 'Classes of type T must have a public new constructor defined
::
Private _InnerRequest As New T() 'Creates a new class of type T when an instance is created of Request
And make the constructors of the other classes Public instead of Friend.
Than you can directly do
Dim Req As New Request(Of Individual)()
Req.InnerRequest.FirstName = "Herman"
#Barry already answered what the main problem is, but here's an alternate syntax if you prefer object initializers:
Req.InnerRequest = new Individual() With { FirstName = "Herman" }
Or, if you prefer, you could overload the constructor for your Individual class:
Dim individual As New Individual("Herman")
Req.InnerRequest = individual
With the Individual class looking like:
Public Class Individual
Public FirstName As String
Public LastName As String
Friend Sub New()
End Sub
Friend Sub New(firstName As String)
Me.FirstName = firstName
End Sub
End Class
You probably should consider restricting the T to some Entity class:
Public Class Request(Of T As Entity)
From which both Individual and Commercial will inherit:
Public Class Individual : Inherits Entity
Then maybe declare an overridable property Name of type String on this Entity class (which can be abstract/MustInherit), this should provide some flexibility. Otherwise you'd be having a hard time consuming your design pattern.
How to pass a object that is initialized from a derived class to a method that has Interface as the parameter? Below is the example of what I'm trying. Is it possible? Please suggest any better way of doing.
Public Interface IFruit
Property Name As String
Property Color As String
End Interface
Public Class Fruit
Implements IFruit
Private _Name As String
Private _Color As String
Public Property Color As String Implements IFruit.Color
Get
Return _Color
End Get
Set(value As String)
_Color = value
End Set
End Property
Public Property Name As String Implements IFruit.Name
Get
Return _Name
End Get
Set(value As String)
_Name = value
End Set
End Property
End Class
Public Class FruitExtended
Inherits Fruit
Private _Taste As String
Public Property Taste() As String
Get
Return _Taste
End Get
Set(ByVal value As String)
_Taste = value
End Set
End Property
End Class
Public Class A
Public Sub ProcessFruit(F as IFruit)
'...
'Do something
End Sub
will the below code work? or how to achieve this in other ways?
Public Sub Test()
Dim F1 as new FruitExtended()
ProcessFruit(F1)
End sub
End Class
I didn't try your code, but - in general - interfaces are good because they define a behaviuor rather than a state (properties). So maybe you could rethink your design and ask yourself what the ProcessFruit is supposed to do with a IFruit.
Some languages even disallow to declare properties in interfaces, other than constants. Java is an example.
I’m working on some partial classes but I can’t figure out how to do it.
This is my classes:
Partial Public Class Form
Private InfoField() As Info
Private FormgroupField() As FormGroup
Private tittle As String
Public Property Info() As Info()
Get
Return Me. InfoField
End Get
Set
Me. InfoField = value
End Set
End Property
Public Property FormGroup() As FormGroup()
Get
Return Me.GromGroupField
End Get
Set
Me.FormGroupField = value
End Set
End Property
Public Property tittle() As String
Get
Return Me.tittleField
End Get
Set
Me.tittleField = value
End Set
End Property
End class
Partial Public Class Info
Private ChangeFormField() As ChangeForm
Private formYearField() As FormYea
Private idField As String
Public Property ChangeForm() As ChangeForm()
Get
Return Me.changeFormField
End Get
Set
Me.changeFormField = value
End Set
End Property
Public Property FormYear() As FormYear()
Get
Return Me.formYearField
End Get
Set
Me.formYearField = value
End Set
End Property
Public Property id() As String
Get
Return Me.idField
End Get
Set
Me.idField = value
End Set
End Property
End Class
Partial Public Class ChangeForm
Private idField As String
Private valueField As String
<properties goes here>
End Class
Partial Public Class FormYear
Private idField As String
Private valueField As String
<properties goes here>
End Class
And for the class FormGroup the organization is the same.
I want to build partial classes to extend these classes, so when I use all this classes in another project I only have to deal with (see) the topmost class (Form) and not the other classes (like Info and FormGroup. This is what I like to do:
Partial Public Class Form
Public Sub Init()
Me.Info = New Info
Me.FormGroup = New FormGroup
Me.Info.Init()
Me.FormGroup.Init()
End Sub
End Class
Partial Public Class Info
Public Sub Init()
Me.FormYear = New FormYear
Me.ChangeForm = New ChangeForm
Me.changeForm.Init()
End Sub
But I can’t write
Me.Info = New Info
Me.FormGroup = New FormGroup
because it is arrays with classes. How can I do it in my Form and Info class?
Thanks in advance.
You must first create an array, then loop over the array and assign each element. Also, unless you have a good, strong reason, do this in the constructor rather than a separate init method.
Public Class Form
Public Sub New()
'In VB, you give the max index, not the length.
'I prefer listing this as (whatever I want for length) - 1
Me.Info = New Info(size - 1) {}
For i = 0 to size - 1
Me.Info(i) = New Info()
Next
'similarly for other fields
End Sub
End Class
Alternatively, if you find yourself with a lot of array fields, and they all have default constructors, you could create a FixedCollection class that would encapsulate the repetitive initialization code.
Public Class FixedCollection(Of T As New)
Inherits Collection(Of T)
Public Sub New(ByVal size As Integer)
MyBase.New(New T(size - 1) {})
For i = 0 to size - 1
Me.Items(i) = New T()
Next
End Sub
'alternate constructors if you need additional initialization
'beyond construction of each element
Public Sub New(ByVal size As Integer, ByVal creator As Func(Of T))
MyBase.New(New T(size - 1) {})
If creator Is Nothing Then Throw New ArgumentNullException("creator")
For i = 0 to size - 1
Me.Items(i) = creator()
Next
End Sub
'this overload allows you to include the index in the collection
'if it would matter to creation
Public Sub New(ByVal size As Integer, ByVal creator As Func(Of Integer, T))
MyBase.New(New T(size - 1) {})
If creator Is Nothing Then Throw New ArgumentNullException("creator")
For i = 0 to size - 1
Me.Items(i) = creator(i)
Next
End Sub
'other collection overrides as needed here
End Class
EDIT: Added constructor overloads for when an element constructor is not enough.
If you only use the constructors with a creator parameter, you could remove the New constraint on T.
Use the overloads as follows:
Public Class Form
Private InfoField As New FixedCollection(Of Info)(10,
Function()
Dim ret As New Info()
ret.Init()
End Function)
End Class
Based on your comments, it seems like the Init methods are an unfortunate necessity. If possible, I would recommend that you find a way to get the generated constructor changed to call this method (defined in the generated code using partial methods) for you rather than forcing you to call it yourself.
You can initialize an Array of a Class like this:
Public FieldTypes As FieldTypeInfo() =
{
New FieldTypeInfo("Byte", 1),
New FieldTypeInfo("Int16", 2),
New FieldTypeInfo("Int32", 3),
New FieldTypeInfo("Integer", 3),
New FieldTypeInfo("Int64", 4),
New FieldTypeInfo("UInt16", 5),
New FieldTypeInfo("UInt32", 6),
New FieldTypeInfo("UInteger", 6),
New FieldTypeInfo("UInt64", 7)
}
Maybe I just don't know what to search for, but I'm going a little bonkers here trying to figure out how to create a collection of inherited classes. The base class, I will never use.
Basically, I have 3 components:
A base class call ImageFormat
Child classes of ImageForm
Code in Sub Main() to loop create a
collection and loop through it.
So it does it, #3. The problem is that it always gets the last item added to the collection and uses it's values only.
Here's my Base Class:
Public MustInherit Class ImageFormat
Protected Shared _extentions As String()
Protected Shared _targettype As String
Protected Shared _name As String
Public ReadOnly Property Extentions As String()
Get
Return _extentions
End Get
End Property
Public ReadOnly Property TargetType As String
Get
Return _targettype
End Get
End Property
Public ReadOnly Property Name As String
Get
Return _name
End Get
End Property
End Class
And here are the child classes:
Class WindowsEnhancedMetafile
Inherits ImageFormat
Sub New()
_extentions = {"EMF"}
_targettype = "jpg"
_name = "Windows Enhanced Metafile"
End Sub
End Class
Class WindowsBitmap
Inherits ImageFormat
Sub New()
_extentions = {"BMP", "DIB", "RLE", "BMZ"}
_targettype = "jpg"
_name = "Windows Bitmap"
End Sub
End Class
Class WindowsMetafile
Inherits ImageFormat
Sub New()
_extentions = {"WMF"}
_targettype = "jpg"
_name = "Windows Metafile"
End Sub
End Class
(don't know if these child classes need to different, like just instantied from ImageFormat type or Singleton patterns - would appreciate anything thoughts you have on this)
Then, my routine is:
Sub Main()
Dim imgFormats As New List(Of ImageFormat)
imgFormats.Add(New WindowsBitmap)
imgFormats.Add(New WindowsMetafile)
imgFormats.Add(New WindowsEnhancedMetafile)
Dim name As String = String.Empty
For Each imgFormat In imgFormats
name = imgFormat.Name
Console.WriteLine(name)
Next
Console.ReadLine()
End Sub
This returns Windows Enhanced Metafile three times at the Console. What am I doing wrong here?
The three properties:
Protected Shared _extentions As String()
Protected Shared _targettype As String
Protected Shared _name As String
Are marked as Shared - they belong to the class not the object.
Each time you assign a new value to _name it overrides the old value, thus why you get the same name printed each time.
It should be:
Protected _extentions As String()
Protected _targettype As String
Protected _name As String
Well, your _name et al are Shared, which means they are class-level variables. When you're adding WindowsEnhancedMetafile, it happens to overwrite these fields with WMF-specific information. If you changed your code to:
imgFormats.Add(New WindowsMetafile)
imgFormats.Add(New WindowsEnhancedMetafile)
imgFormats.Add(New WindowsBitmap)
you would've had "Windows Bitmap" printed three times.
All you have to do is to change your field declarations to
Protected _extentions As String()
Protected _targettype As String
Protected _name As String