Using VB.Net
I have about 60 Child forms
Each have a variable with same name.
In Main form I want to set the value of the variable of the active child.
One way of doing that is like
Select Case Me.ActiveMdiChild.Name
Case "formName"
frmformName.Variable=0
I donot want to do that as it involves writing many cases and I may miss some.
Is there some other way of doing it .
I tried
Dim O as Object = Me.ActiveMdiChil
O.VariableName= 0
and its various variants but its not working
Another way to do that is with an Interface, example:
Public Interface IChildVariable
Property Variable() As Integer
End Interface
Public Class Form1
Implements IChildVariable
Private _MyVariable As Integer
Public Property Variable() As Integer Implements IChildVariable.Variable
Get
Return _MyVariable
End Get
Set(ByVal value As Integer)
_MyVariable = value
End Set
End Property
End Class
Then you can just have a single check point:
If TypeOf Me.ActiveMdiChild Is IChildVariable Then
DirectCast(Me.ActiveMdiChild, IChildVariable).Variable = 0
Else
''Throw Exception
End If
Related
Hi there have a list of custom objects that I need to be able to sort, one property within another. How do I go about doing this using .Net. Normally I would carry out all sorting requirements within the SQL that delivers the data, unfortunately in this case I don't have control over that generation of the raw data. I consequently have no experience of sorting content using .Net functions such as Linq and/or IComparable. An impression of the code elements involved are listed below:
Public Class CustomObject
Public Property PrimaryItem As String
Get
Return _primaryItem
End Get
Set(ByVal value As String)
_primaryItem = value
End Set
End Property
Public Property SecondaryItem As String
Get
Return _secondaryItem
End Get
Set(ByVal value As String)
_secondaryItem = value
End Set
End Property
End Class
Public Class CustomObjectList
Inherits List(Of CustomObject)
Public Sub New()
End Sub
End Class
In essence I want to be able to sort CustomObjectList according to SecondaryItem within PrimaryItem:
PrimaryItem1
SecondaryItem1
SecondaryItem2
etc...
PrimaryItem2
SecondaryItem1
SecondaryItem2
etc...
etc...
Hoping that some kind person will be able to give me a 'leg up' in usage of either Linq and/or iComparable.
Dim result = MyList.OrderBy(Function(x) x.PrimaryItem).ThenBy(Function(x) x.SecondaryItem)
I have this class:
Public Class clsServCasam
Public ID As Long
Public CANT As Decimal
Public PRICE As Decimal
End Class
I create a variable of that type and get the object from an API result:
Dim myObj As clsServCasam()
Dim rsp As HttpWebResponse = CType(rq.GetResponse(), HttpWebResponse)
If rsp.StatusCode = HttpStatusCode.OK Then
Using sr = New StreamReader(rsp.GetResponseStream())
myObj = JsonConvert.DeserializeObject(Of clsServCasam())(sr.ReadToEnd())
End Using
Then I try to get the field names from the object:
For Each p As System.Reflection.PropertyInfo In myObj.GetType().GetProperties()
Debug.Print(p.Name, p.GetValue(myObj, Nothing))
Next
But, instead of class fields (ID, PRICE, ...) I got:
- Length
- LongLength
- Rank
Update
As Steven Doggart pointed out, the above loop won't work because it looks for properties rather than fields. So, I tried changing the loop to this:
For Each p As FieldInfo In myObj.GetType.GetFields()
Debug.Print(p.Name)
Next
But now I'm getting no results at all.
In your code, myObj is not declared as clsServCasam. Rather, it is declared as clsServCasam(), which means it's an array of clsServCasam objects. So, when you use reflection to iterate over its properties, you're getting the properties of the array rather than the actual clsServCasam type.
For instance, this would work more like you're expecting:
For Each item As clsServCasam in myObj
For Each p As PropertyInfo In item.GetType().GetProperties()
Debug.Print(p.Name, p.GetValue(item, Nothing))
Next
Next
However, I think you'll find that that still won't work because it iterates over the properties rather than the fields. In the definition of the clsServCasam class, all of the members are fields rather than properties, so the only properties that it have would be ones that are inherited from Object. You will need to either iterate over the fields using GetFields, like this:
For Each item As clsServCasam in myObj
For Each f As FieldInfo In item.GetType().GetFields()
Debug.Print(f.Name, f.GetValue(item))
Next
Next
Or you'll need to change them to properties:
Public Class clsServCasam
Public Property ID As Long
Public Property CANT As Decimal
Public Property PRICE As Decimal
End Class
Or, if you are using an older version of the VB compiler which doesn't support auto-properties:
Public Class clsServCasam
Public Property ID As Long
Get
Return _id
End Get
Set(value As Long)
_id = value
End Set
End Property
Public Property CANT As Decimal
Get
Return _cant
End Get
Set(value As Decimal)
_cant = value
End Set
End Property
Public Property PRICE As Decimal
Get
Return _price
End Get
Set(value As Decimal)
_price = value
End Set
End Property
Private _id As Long
Private _cant As Decimal
Private _price As Decimal
End Class
I have a public subroutine that is called by many classes. However, I now need to do something in that subroutine that only pertains to a small number of the classes that call it. So instead of going back and adding the property to all of the existing classes, I would like to simply check to see see if that class has that property and if so, then do something with it. But I can't seem to figure out how to simply check for the existence of the member without getting an error.
For example:
Public Class_1
Public a1 as string = ""
Public Sub New()
' when a button is clicked call subroutine "check()"
End Sub
End Class
Public Class_2
Public a1 as string = ""
Public a2 as integer = 0
Public Sub New()
' when a button is clicked call subroutine "check()"
End Sub
End Class
Public Class whatever
Public Sub check(sender as object)
If sender.a2 = 0 then
' do something
End if
End Sub
End Class
I have tried such things as
If not(sender.a2 is nothing) then
If isnothing(sender.a2) then
But I can't get past the fact that I get an error simply by using "sender.a2" since a2 is not always a member of the sender.
How can I check to see if a2 is a member of the sending class without using "sender.a2"?
If you want to see that a field exists you need this:
Dim fi As FieldInfo = sender.GetType().GetField("nameOfFieldHere")
If fi IsNot Nothing
'field exists now get the value
Dim o As Object = fi.GetValue(sender)
End If
Take a look at the documentation Type.GetField Method (String)
There are also overloads available too.
You can test that the Object you are referencing is of a certain type before attempting to use it. Once you've determined it's the right type, you can safely cast to it and then use the right properties like so:
If (TypeOf sender Is Class_2) Then
Dim castObj As Class_2 = CType(sender, Class_2)
'We can now access castObj.a2
End If
If there are multiple classes with the property, it would be sensible to create an Interface which states they have the a2 property and have them all implement it. You can then test their type against the new Interface instead of Class_2.
An alternative option is to use class inheritance to implement a default public method for all classes, and override it in your special Class_2 case for your subclasses.
Dim objects As New List(Of Object)
With New Object
.prop1 = "Property 1"
.prop2 = "Property 2"
objects.add(.instance) 'i mean instance of New Object
End With
is it possible.
I ask new question because last question has mislead information and I don't give right answer. so here code.
No it is not possible. The With statement basically creates an implicit variable. All you can do with that variable is access members and there is no member that returns a reference to the object itself.
If you want succinct code to create, populate and add an object to a list then do this:
myList.Add(New SomeType With {.SomeProperty = someValue,
.SomeOtherProperty = someOtherValue})
Interestingly, you can make it work the way you wanted if you create your own extension method. I was under the impression that you could not extend the Object class but either I was wrong or that has changed because I just tried in VB 2013 and it worked. You can write a method like this:
Imports System.Runtime.CompilerServices
Public Module ObjectExtensions
<Extension>
Public Function Self(Of T)(source As T) As T
Return source
End Function
End Module
and then do something like this:
With New SomeType
.SomeProperty = someValue
.SomeOtherProperty = someOtherValue
myList.Add(.Self())
End With
I'm not sure that that really provides any benefit though, given the availability of the object initialiser syntax that I demonstrated first.
Hmmm... I just realised that that's not actually extending the Object class. It was my original intention to try to do so but then I realised that a generic method was better because it would then return the same type as you call it on. I did just test it with a non-generic method extending type Object and it did still worked though.
You should to create your own class By example :
Public Class Car
Private _NumberCar As Integer
Public Property NumberCar() As Integer
Get
Return _NumberCar
End Get
Set(ByVal value As Integer)
_NumberCar = value
End Set
End Property
Private _ColorCar As Color
Public Property ColorCar() As Color
Get
Return _ColorCar
End Get
Set(ByVal value As Color)
_ColorCar = value
End Set
End Property
Private _OwnerName As String
Public Property OwnerName() As String
Get
Return _OwnerName
End Get
Set(ByVal value As String)
_OwnerName = value
End Set
End Property
End Class
and in the Class where you want to add the cars object do this :
Dim CarList As New List(Of Car)
Dim item As New Car
With item
.NumberCar = 1243
.ColorCar = Color.Red
.OwnerName = "Ibra"
End With
CarList.Add(item)
strong text
-EDIT Fixed
I was missing one thing and doing one thing wrong. First I was missing a function to access the collection by index. And I should of been using a for Loop instead of a for each loop in my module code
I forgot to add this to the collection class
Public Function GetPayRecords(ByVal index As Variant) As PayRecords
Set GetPayRecords = pObjCol.item(index)
End Function
and replaced
For Each vItem In .GetPayRecords
....code to do stuff
Next vItem
with this in the module
Dim x As Integer
For x = 1 To .Count
Debug.Print .GetPayRecords(x).PY_PayRecord.CEOCompanyID
Debug.Print .GetPayRecords(x).PY_PayRecord.OrigBankID
Next x
I'm writing a program that has 8 Classes. Each class represents a specific record type.
I have an overall Class that contains those 8 classes which is for simplicity when coding in the Module. I only have to declare one class which gives me access to all 8 classes. I have a collection which contains all the records types. Once all the logic of loading the individual records is complete they get added to the collection. This all works perfectly and I can see all the records in the collection. The final step, which happens to be where i'm having the problem, I need to extract each item within the collection by record type and write it to a csv. The problem I encounter is trying to iterate through each record.
Here's how the structure looks
Classes
clsAllRecordTypes
clsRecordType1
clsRecordType2
...
clsRecordType8
Collection
clsColRecords
The problem is in the retrieval
Module
Dim PayRecord As PayRecords 'Class of Classes
Dim PayRecordList As bankCollection
...code to load all the payrecords
With payrecordlist
Foreach vItem in .pObjCol
debug.print .pObjCol.Item(?) ' not sure why i can't see all 8
next vItem
End With
When I add vItem to the watch I can see each and every record type filled up with information but yet i Can not access it. Below is the Class of classes and collection
Class of Classes
Option Explicit
'This class is a representation of all the record types that apply to our Payment Manager
'It aggregates all the record types (classes) into one class. That one class is used in the main processing module for simplicty
'
Private pPayRecord As New PayRecord
Private pPNAR_OP As New PNAR_OP
Private pPNAR_RP As New PNAR_RP
Private pSuppACHREC As New SuppACHRec
Private pSuppCCRRec As New SuppCCRRec
Private pSuppCHKRec As New SuppCHKRec
Private pDocumentDelieveryRec As New DocumentDeliveryRecord
Private pInvoiceRecords As New InvoiceRecords
Public Property Get PY_PayRecord() As PayRecord
Set PY_PayRecord = pPayRecord
End Property
Public Property Let PY_PayRecord(ByVal newPayRecord As PayRecord)
Set pPayRecord = newPayRecord
End Property
Public Property Get PA_PNAR_OP() As PNAR_OP
Set PA_PNAR_OP = pPNAR_OP
End Property
Public Property Let PA_PNAR_OP(ByVal newPNAR_OP_Record As PNAR_OP)
Set pPNAR_OP = newPNAR_OP_Record
End Property
Public Property Get PA_PNAR_RP() As PNAR_RP
Set PA_PNAR_RP = pPNAR_RP
End Property
Public Property Let PA_PNAR_RP(ByVal newPNAR_RP_Record As PNAR_RP)
Set pPNAR_RP = newPNAR_RP_Record
End Property
Public Property Get AC_SuppACH() As SuppACHRec
Set AC_SuppACH = pSuppACHREC
End Property
Public Property Let AC_SuppACH(ByVal newSuppACH_Record As SuppACHRec)
Set pSuppACHREC = newSuppACH_Record
End Property
Public Property Get AC_SuppCCR() As SuppCCRRec
Set AC_SuppCCR = pSuppCCRRec
End Property
Public Property Let AC_SuppCCR(ByVal newSuppCCR_Record As SuppCCRRec)
Set pSuppCCRRec = newSuppCCR_Record
End Property
Public Property Get AC_SuppCHK() As SuppCHKRec
Set AC_SuppCHK = pSuppCHKRec
End Property
Public Property Let AC_SuppCHK(ByVal newSuppCHK_Record As SuppCHKRec)
Set pSuppCHKRec = newSuppCHK_Record
End Property
Public Property Get DocumentDeliveryRecord() As DocumentDeliveryRecord
Set DocumentDeliveryRecord = pDocumentDelieveryRec
End Property
Public Property Let DocumentDeliveryRecord(ByVal newDocumentDeliveryRecord As DocumentDeliveryRecord)
Set pDocumentDelieveryRec = newDocumentDeliveryRecord
End Property
Public Property Get InvoiceRecords() As InvoiceRecords
Set InvoiceRecords = pInvoiceRecords
End Property
Public Property Let InvoiceRecords(ByVal newInvoiceRecord As InvoiceRecords)
Set pInvoiceRecords = newInvoiceRecord
End Property
Collection Class
Option Explicit
Private pHeaderRec As New HeaderRec
Private pNewPayRecords As New PayRecords
Public pObjCol As Collection
Private pTrailerRec As New TrailerRec
Private Sub Class_Initialize()
Set pObjCol = New Collection
End Sub
Private Sub Class_Terminate()
Set pObjCol = Nothing
End Sub
Public Property Get HD_HeaderRecord() As HeaderRec
Set HD_HeaderRecord = pHeaderRec
End Property
Public Property Let HD_HeaderRecord(ByVal newHeaderRecord As HeaderRec)
Set pHeaderRec = newHeaderRecord
End Property
Sub Add(ByVal newPayRecs As PayRecords)
pObjCol.Add newPayRecs
End Sub
Property Get Count() As Long
Count = pObjCol.Count
End Property
Public Property Get TR_TrailerRecord() As TrailerRec
Set TR_TrailerRecord = pTrailerRec
End Property
Public Property Let TR_TrailerRecord(ByVal newTrailer_Record As TrailerRec)
Set pTrailerRec = newTrailer_Record
End Property
I'm sorry if this doesn't help, because your explanation is hard to follow. But, I'll assume that you are saying that you have an object of type Payrecords, which contains references to seven other objects of types PNAR_OP, PNAR_RP, etc. Each of these latter objects contain "20-30 fields" that you want to get at. You ask how to loop through all of these.
A simple way to do that is to use an array. Yes, you can foreach through Collections or (better yet) Dictionaries, but arrays work, they're easy to understand, and they were iterating through objects when Collections were running around in diapers.
Let your Payrecords have a property of type Object(6). When you initialize it, instantiate one of each of the seven objects and add it to the array (for example, "Set myPayrecordsObjects(3) = New SubCCRRec" and so on). To loop through, just use a for next loop to loop through the 7 objects.
Since you provide no information about how you structure your "fields" within these objects, I'll recommend that you iterate through the Fields collection of the ADO object to loop through those. (If you're not using the ADO Fields collection, well, your attention to detail gets mine in return.)