I have code that handles multiple events. FYI - I use Devexpress Components. I have two items, a Lookupedit and a GridLookupEdit, that are handled by the same code. I am trying to do something like the following:
Dim type = sender.GetType()
Select Case DirectCast(sender, Type).Name
Case "mgrLUE"
log("View metrics for manager: " & mgrLUE.Properties.GetDisplayText(mgrLUE.EditValue), Me.Name)
Case "sectLUE"
log("View metrics for section: " & sectGLUE.Properties.GetDisplayText(sectGLUE.EditValue), Me.Name)
End Select
I am getting errors at the select case line. I cant figure out how to dynamically get the type to be able to direct cast to it. The types will be DevExpress.XtraEditors.GridLookUpEdit and DevExpress.XtraEditors.LookUpEdit in this case. I have tried searching for a solution, but everything I have tried is failing.
Thank you for the help.
Casting can't be done dynamically because its sole purpose is to let the compiler know that you expect an object to be of a certain type. This is necessary so that the compiler knows what members the object contains when you try to access it.
I should mention that VB.NET has a feature called late binding, which allows you to access members of a type wrapped in an Object by looking up if the member you're trying to access exists at runtime. Using late binding, however, is not recommended as it is very easy to make mistakes and break your code.
Now, as for your problem: Casting can be done if an object is of a certain type, or if it inherits from that type. Since I'm guessing what you're using are controls (that you've placed on your form) they all should inherit from System.Windows.Forms.Control, thus you can cast them to that which contains the base property Name:
Select Case DirectCast(sender, Control).Name
Related
A table in MS Access opened in Design View exposes several properties, as does the table's Property Sheet. Many of these properties are undocumented or documented only for other objects. The question is, to which object do these properties belong? Further, how does one identify them in code? Pressing F1 for context help in each case reveals no clues.
Examples include (and recognize that the names below follow from their visual context, not an object model):
Field.Description is a column in Design View (along with Field Name and Data Type) but is undocumented. Also, iterating DAO.Field.Properties reveals no Description field and references to the property fail.
Table.Description appears in the Property Sheet but also is undocumented.
Table.Filter and Table.OrderBy and their ~OnLoad counterparts appear on the Property Sheet but are documented only for other objects. I understand that information specified here is intended somehow to flow through to forms for which the table is the RecordSource, but the mechanism is not obvious and still leaves the initial question, flowing through from which object's property.
Table.LinkChildFields and Table.LinkMasterFields appear in the Property Sheet but are documented only for other objects. Also, their use in this context is not obvious.
Other table properties on the Property Sheet tell the same tale.
Any thoughts, in general or specific to any of the foregoing, would be most helpful and appreciated.
To show properties of some Access database object (table, query, form, report, ...), we can do this on VBA, defining this global function:
Function objShowProperties(ByVal xobj As Object)
Dim i As Long, varPropValue, prop As Object
On Error Resume Next
'
' loop over properties:
'
i = 0
For Each prop In xobj.Properties
varPropValue = prop.Value
'
' sometimes we have error accessing property value:
'
If (Err <> 0) Then
varPropValue = "[UNAVAILABLE]"
Err.Clear
End If
Debug.Print prop.Name, "=", varPropValue
i = i + 1
Next
On Error GoTo 0
Set prop = Nothing
objShowProperties = i
End Function
In my Acccess db I've a table named customers.
To show properties of this table, I call the above function like this:
objShowProperties CurrentDb.TableDefs("customers")
In my debug console, I got this:
All listed properties can then be accessed directly on VBA code, eg, RecordCount property:
dim lngRecords as long
lngRecords = CurrentDb.TableDefs("customers").Properties("RecordCount")
Hope this will help you.
A few things:
Field.Description is a column in Design View (along with Field Name and Data Type) but is undocumented.
No, it is not un-documented.
You are confusing DAO, and that of ms-access.
DAO "field" does not have a description property. So, it not un-documented at all.
Also in Access, there is help. You an put your cursor in the description, and hit help, and you get this:
so, place cursor here, and hit f1 for help:
And now you get this:
So, you are confusing the database engine object called DAO.FIELD with that of ms-access and it allowing you to have/enjoy/see a description in the table desinger.
I should point out that the DAO object model does not have a table designer!!!
In fact, what Access does is add's a custom property to the field, and then display's that. So, field.Description is not un-document, it in fact does not exist.
As noted in the other post here, you can "interate" all of the properties. However, if you use the database engine outside of ms-access, and EVEN create fields in code (or even by sql commands), you WILL STILL find that no descripton property exists. However, as noted, there is this thing called help, and you can give help a try, as it will explain what the description setting in ms-access does.
However, at the end of the day, field.description is not un-documented, and in fact does not exist.
so, if you read/look at/see documentaiton for the DAO field object, then these properties and options will not be found.
After all, you might be using c++, c# or some other system and that database engine that MS-Access just also happens to use.
MS-Access is not the database here. It is a tool that lets you build software, and forms and reports, and write code.
When you using MS-Access, you are not required to use the JET (now called ACE) database engine to store your data. You are free to use the Oracle database, or SQL server or whatever.
So, features of Access and things like link master fields etc.?
Those are MS-Access features, and not the database engine (ACE) features.
I just installed Visual Studio 2010 Service pack (proposed on Windows Update), and I can see a new feature on the "intellisense" that means when I write a Function or Sub in VB.NET it doesn't auto-complete parameters with ByRef or ByVal...
1) Is there anyway that I can configure this option back to how it was before?
2) If I don't specify ByX, which one is used by default? (it seems like it is always ByRef)
It seems that this post covers your question:
http://msmvps.com/blogs/carlosq/archive/2011/03/15/vs-2010-sp1-changing-quot-byval-quot-vb-net-code-editor-experience.aspx
So no, there is no way to get the old behaviour. From now on ByVal is the default (what it was before) and it won't get added automatically to the method parameters.
In my opinion this is a good decision since it's making VB.NET a bit more consistent with C# and avoids unnecessary "noises"(it's already verbose enough).
Old behaviour:
Private Sub test(ByVal test As String)
End Sub
New behaviour
Private Sub test(test As String)
End Sub
Tim covered what you asked directly, but something else to keep in mind is that any reference type variable, like a user defined class even if passed by value will allow you to make changes to that instances properties etc that stay. It won't however allow you to change the entire object. Which may be why it seemed to you to be defaulting to by reference
Public Sub (Something As WhateverClass)
Something = New WhateverClass 'will result in no changes when outside this method
Something.Property1 = "Test" 'will result in an updated property when outside this method
End Sub
From MSDN:
The value of a reference type is a pointer to the data elsewhere in memory.
This means that when you pass a reference type by value,
the procedure code has a pointer to the underlying element's data,
even though it cannot access the underlying element itself. For
example, if the element is an array variable, the procedure code does
not have access to the variable itself, but it can access the array
members.
Beware when transferring routines to VBA, where the default is ByRef (see, e.g., "The Default Method Of Passing Parameters" at the bottom of this page, by the great Chip Pearson).
That can be messy.
I have an existing class structure in place and want/need to use that as a data source for a series of reports using vb and 2005, (though we are almost ready to move to 2010, so if that will solve this ill move today!)
Using gotreportviewer sample for nested objects ive added a reportmanager class exposing a getdata method which ive populated with all my data and returned a list(of object). the data is there and correct at the point of databinding, i can add and reference top level properties, however not matter what syntax i try i cant reference the fields in nested classes/lists. I get various messages ranging from "#Error" in the ouput field to nothing, to wont compile.
my class structure is roughly this in short form:
Assembly0
Class ReportManager
TheData as List(Of Object)
New() 'that populates TheData from the class structure below
GetData() as List(of Object)
Assembly1
Class Test
aProperty1 as String
aProperty2 as Int
aProperty3 as String
aProperty4 as String
aProperty4 as List(of aType1)
Assembly2
Class AaType1
aProperty1 as String
aProperty2 as Int
aProperty3 as String
aProperty4 as String
aProperty4 as List(of aType2)
aProperty4 as List(of aType3)
aProperty4 as String
Assembly3
Class aType2
aProperty1 as Boolean
aProperty1 as String
you get the idea
and so on.....
in my main app
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
' Create an instance of our ReportManager Class
Try
' trust assemblies used in get data
ReportViewer1.LocalReport.ExecuteReportInCurrentAppDomain(Assembly.GetExecutingAssembly().Evidence)
ReportViewer1.LocalReport.AddTrustedCodeModuleInCurrentAppDomain("assy1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=1234")
ReportViewer1.LocalReport.AddTrustedCodeModuleInCurrentAppDomain("assy2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=1234")
' etc through ALL dependant assemblies
' create datamanager, that will populate its TheData property
Dim reportMan As Data.Reporting.Manager = New Data.Reporting.Manager(18) ' test id sent
' this is the method from the gotreportviewer sample, which only allows you to reference top level properties, regardless of syntax used. i.e. =Fields!Prop.Value.SubProp
' doesnt work
'ReportViewer1.LocalReport.DataSources.Add(New ReportDataSource("DummyDataSource", reportMan.GetData))
'Me.ReportingDataBindingSource.DataSource = reportMan.GetData
' this is the only method I have found that allows me to reference an objects nested property and its fields.....?
Data = reportMan.GetData()
Me.ReportViewer1.ProcessingMode = Microsoft.Reporting.WinForms.ProcessingMode.Local
Me.ReportViewer1.LocalReport.DataSources.Add(New ReportDataSource("Data_Reporting_ReportingData", Data))
' fortnatley there is only ever one test in the list, HOWEVER there will be 4 specimens and n stages below that and so on..
Dim SpecimenData As SpecimenList = Data(0).Specimens
Me.ReportViewer1.LocalReport.DataSources.Add(New ReportDataSource("Tests_Specimen", SpecimenData))
' so this method is no good either. currently only a test its just returning the first specimen.
'Dim StageData As Tests.Stages = Data(0).Specimens(0).Stages
'Me.ReportViewer1.LocalReport.DataSources.Add(New ReportDataSource("Tests_Specimen", SpecimenData))
' render report
Me.ReportViewer1.RefreshReport()
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
Fixes i found online/googling:
You must add "ExecuteReportInCurrentAppDomain",
done that no difference.
You must add
Assembly: AllowPartiallyTrustedCallers() to AssemblyInfo.vb, No difference.
You must strongly name you dependent assemblies, done that and it did get rid of
an error regarding a call being made in the "Code" property of the report
(for localization).
have tried the =Fields!Property.Value.SubProperty syntax and it DOESN'T work! no matter what variation I try.
' in the rdlc - this syntax works for a top level properties
=Sum(Fields!TestVersion.Value, "Data_Reporting_ReportingData")
' using the alternate method list in the above code this works
=First(Fields!Index.Value, "Tests_Specimen")
' but these dont for its child properties
=First(Fields!Specimens.Value.Index, "Data_Reporting_ReportingData")
=Fields!Specimens.Value.Index
=Fields!Specimens.Value.Index.Value
So does that mean I have no choice but to create something like
Dim SpecimenData As Tests.SpecimenList = Data(0).Specimens for every single nested object? Also for obvious reasons I'd rather not have to flatten the entire datastructure as it's massive.
I have tried everything I can find on this, not much out there and everything points back to the same three four articles/blog posts that just aren't working for me, their samples unmodified work, but none of them work when applied to nested lists or nested objects of inherited list types.
Does anyone have any sample code of using objects with nested lists that actually works? as none of the ones I could find online work with anything but the simplest of scenarios. i.e. one assembly, or one code file or no nested lists or simple/native types.
I've been at this the best part of A WEEK! I'm now bald and stressed please help.
Failing that can anyone suggest a thrid party vendor that does support this sort of thing?
does crystal? pebble?
Apologies for the wall of text...
Matma
I´m Looking for almost the same, except, that I have objects that have as property other objects, no List of objects, any way, you asked if Crystal Reports do this kind of thing, YES IT DOES, it´s a little bit difficult to do it, but it does.
I don´t know why it´s so difficult to work with that kind of think on now days. Because we are aways working with persistance Frameworks, like Entity Framework, and others, so, you do a hell of a job with a Persistance, and when you go to reports, you need to back to your DataBase model if you want easy work! So waste of time!
I Just have found, it´s possible to do it in report viewer, But it had a problem in visual studio 2010, it´s fixed in SP1 but you need to set all your classes that are used as nested objects as Serializable
Please read : http://wraithnath.blogspot.com.br/2011/04/reportviewer-object-datasource-nested.html
This is probably a simple one but I can't seem to figure it out.
I have a bunch of form items created by the form designer declared as (in frmAquRun.Designer.vb)
Public WithEvents btnAquRunEvent1 As VisibiltyButtonLib.VisibilityButton
Public WithEvents btnAquRunEvent2 As VisibiltyButtonLib.VisibilityButton
... etc
And I basically want to be able to supply a number to a function access each of these fields. So I wrote this function. (in frmAquRun.vb)
Const EVENT_BUTTON_PREFIX As String = "btnAquRunEvent"
Public Function getEventButton(ByVal id As Integer) As Windows.Forms.Button
Dim returnButton As Windows.Forms.Button = Nothing
Try
returnButton = DirectCast(Me.GetType().InvokeMember(eventButtonName, Reflection.BindingFlags.GetField Or Reflection.BindingFlags.Public Or Reflection.BindingFlags.Instance, Nothing, Me, Nothing), Windows.Forms.Button)
Catch ex As Exception
End Try
Return returnButton
End Function
But it always seems to be generating field not found exceptions.
The message in the exception is "Field 'ATSIS_ControlProgram.frmAquRun.btnAquRunEvent1' not found.".
The namespace and form name in the message are correct. Any idea what i'm doing wrong?
The problem is that for WithEvents fields, VB actually creates a property that does the necessary event handler attaching and detaching. The generated property has the name of the field. The actual backing field gets renamed to _ + original name.1)
So in order for your code to work just prefix the button name by _ or use the BindingFlag that corresponds to the property getter (instead of GetField).
Alternatively, you can do this a lot easier by using the Controls collection of the form:
returnButton = DirectCast(Me.Controls(eventButtonName), Windows.Forms.Button)
But beware that this only works if the button is top-level, i.e. not nested within a container control on the form.
1) This is an implementation detail of the VB compiler but it’s portable (especially to Mono’s vbnc compiler) since the handling for WithEvents fields is described in great detail in the VB language specifications.
The problem is that the event handlers aren't really fields. As compiled they're really properties that implement add_btnAquRunEventX, remove_btnAquRunEventX and fire_btnAquRunEventX methods. There are ways of using reflection to get around this, but that's probably not the best way to approach the problem. Instead you can simply create a List<> and populate it with the event handlers, then index into that list.
I'm a little rusty in VB syntax but it should look something like this:
Dim events = New List<EventHandler>()
events.Add( btnAquRunEvent1 )
events.Add( btnAquRunEvent2 )
....
events( 0 )( null, EventArgs.Empty )
Take a step back though and evaluate why you're invoking by index. There may be a simpler way of abstracting the whole thing that doesn't involve all this indirection.
I have an object, o, and a type, T. I'd like to use reflection to change object o to type T at runtime without instantiating it.
The equivalent at compile time would be:
Dim p as Point = Nothing
I know how to use Activator.CreateInstance to create an instance at run time that is equivalent to:
Dim p as New Point()
But i don't want to do this. I have no knowledge of the type's constructor parameters and some types don't have a parameterless constructor. eg. Font.
So, to sum up, I'd like a way of performing the equivalent of:
Dim o as T = Nothing
In case you're wondering why I'm doing this, it's because I'm using a PropertyGrid on a form to edit types. If this is the first time for editing, say, a Font, then passing an uninitialised Font to the PropertyGrid makes the grid display the default values.
Cheers.
ETA:
I tried 'o = GetUninitializedObject(T)', but the PropertyGrid either wants a properly initialised object or an object, with a defined type, set to nothing.
I've actually solved my particular problem here:
how-to-use-the-property-grid-in-a-form-to-edit-any-type
, but i'd still be interested to know how to assign a type at run-time without the use of a wrapper class (which I was lucky enough to be using).
The closest thing would be to set o to default(T). Assuming the default is not Nothing (null), you'll get a default value such as Rectangle.Empty or 0 (int).
Nothing (null) doesn't have a type associated with it, so if o as object, (T) Nothing won't help.