C# - Generating Code - Get A Proper String Representation Of Nullable Type?
Mar 17, 2010
So I'm building an application that is going to do a ton of code generation with both C# and VB output (depending on project settings). I've got a CodeTemplateEngine, with two derived classes VBTemplateEngine and CSharpTemplateEngine. This question regards creating the property signatures based on columns in a database table. Using the IDataReader's GetSchemaTable method I gather the CLR type of the column, such as "System.Int32", and whether it IsNullable. However, I'd like to keep the code simple, and instead of having a property that looks like:
[Code]...
View 2 Replies
ADVERTISEMENT
Jan 18, 2010
how to implement Nullable Parameter of type string in vb.net
Function:
sub savedetail(byval name as string, byval age as integer)
if name isnot nothing then
some work
end if
[code]....
View 1 Replies
Aug 22, 2009
Dim strFilename As String strFilename = Format(Now, "ddmmyyyyhhmmss"
That generates the day number month and so on. But i want to generate a string with "VB Code Snippet" then after that just any 5 letters or numbers so it might generate "VB Code Snippet 7ef82"
View 17 Replies
Mar 11, 2010
I am currently working on a custom data type, and wanted to implement a = operator.
I data type is a nullable date that returns a string value if date was supplied.
I want to allow the variable to be set like this
Dim nd as New NullableDate nd = Today Does anyone know how this can be done, or can anyone point me in the right direction?
View 9 Replies
Sep 15, 2010
I have a Job Register Table and that table doesn't have any records.
This is my LINQ code:
Dim QRecordCount = (From LC In CntxtJobDetails.JobRegistrations _
Where LC.JobCode <> 0 _
[code].....
View 1 Replies
Aug 18, 2010
When i execute this linq to sql command its given an error "The null value cannot be assigned to a member with type System.Int32 which is a non-nullable value type." 0 Records in my Commotidy Table
I want generate manual number and get the last CommodityCode.My Code as follow,
Dim QRecordCount = From RC In cntxtCommodity.CommodityMasters _
Where RC.CommodityCode <> 0 _
Select RC.CommodityCode[code].....
View 1 Replies
Dec 14, 2011
I have a generic Class I'm using to hold information loaded from a database.I have a method which takes a DataRow as an argument, uses the object's known column name and extracts the data from the DataRow, such that:Dim loadData As T = CType(myDataRow("myColumnName"), T))works as my default assignment in most cases.Unfortunately, due to some horrifying design constraints, some of my columns may be null, and may also be taken from enumerations.This means that when <T> is Nullable(Of SomeEnumeration) the above code does not work because I can't cast 0 directly to SomeEnumeration.Zero.Is there some way to check whether <T> is Nullable(Of [Enum])? Or some way to write a method which allows Integers to be cast to Nullable(Of [Enum])?I feel like I'm forgetting something that would allow me to write one of the other of these, but my weak google-fu is turning up nothing.
EDIT: Okay, thanks to dasblinkenlight's answer below, I can detect when this circumstance is occurring, but what I need to do now is to take a type <T> which I know is Nullable(Of SomeClass), get a type reference to SomeClass and then create a new object of type Nullable(Of SomeClass) and assign that to LoadData.My problem was that I had a lot of difficulty in finding any function which would accept baseType as an actual Type.Parse accepted baseType as a parameter, I knew baseType was an [Enum] type because of dasblinkenlight's code, so I was, in this instance, able to code a solution. It's a solution which is very specific to my problem (i.e., T is Nullable(of SomeEnumeration)), but it's a solution nonetheless.
View 2 Replies
Feb 15, 2010
I am trying to convert a string to a single. Ive tried csng() directcast() and single.parse. The first two methods crash. Single.parse says input string was in incorrect format. The number is 777.7932 so should convert fine. Ive tried it this way:
'x = single.parse(pts(0), globalization.NumberStyles.AllowDecimalPoint)
how can i convert a string representation of a single data type that is read from a text file into its single data type. I checked control panel and globalization settings are set to english.
View 6 Replies
Jun 3, 2011
I want to make a hashtable of object references and I want a different object's reference to be the key. How can I do this in vb.net? In java (assuming I am using the default toString method and that add() takes a string as a key and an object ref as the value) this would be something like: hashtable.add(obj1.toString(), obj2)
I do not want to use a vb.net gethashcode() function because I want deep clones of objects to have different identifiers. A related question is what is the default toString in vb.net? How can I get a string that represents an object reference in vb.net?
View 3 Replies
Jan 12, 2012
<edit> Now showing the difference as a DECIMAL. Result looks like zero every time. </edit>Disclaimer: This code is provided "as-is" and should be treated as Freeware.( However any donations would be welcome as I have a "so-so" part-time job ).Please note all real numbers to be used should be in this format
"0.000000000000"Do not use numbers in string format in scientific notation like "1.2345E -06"I was feeling bored and decided to add to the code from JohnWein in this thread where I have used a routine that will multiply the contents of two long strings together.>>[url]I have now added a bit of code so you can multiply two really long numbers with or without a decimal point as a full-stop ( period or dot, call it what you like ).
[code]...
View 5 Replies
Jan 23, 2012
I am trying to log the contents of an object to a text file. If I do a debug.print of the object itself in the immediate window, it prints all of the values of the object's properties:
?mDb.DatabaseOptions
{Microsoft.SqlServer.Management.Smo.DatabaseOptions}
AnsiNullDefault: False
...
UserData: Nothing
However, I can't seem to access this as a string in code due to a type mismatch. I assumed I could get this information using the .ToString method, but all that returns is the object description with none of the properties or values:
?mDb.DatabaseOptions.ToString
"Microsoft.SqlServer.Management.Smo.DatabaseOptions"
View 2 Replies
Jan 14, 2011
I 've an ArrayList and to join all its elements with a separator in one string I m using...
Dim s As String = String.Join(",", TryCast(myArrayList.ToArray(GetType(String)), String()))
however, I would know if there is a smarter/shorter method to get the same result,or same code that looks better...
View 2 Replies
Aug 7, 2009
I want to retrieve an object by using a string representation of the objects name. For example lets say i want to change the font of 3 labels on a form programatically. Instead of changing the font property for each individual label like so:
Label1.Font = FontDialog1.Font
Label2.Font = FontDialog1.Font
Label3.Font = FontDialog1.Font
I want iterate through the labels in a For..next loop like so:
[Code]..
View 4 Replies
Jan 18, 2012
I had a weird series of errors involving e.Graphics.DrawString() when painting a panel.I am using a barcode font [Code 128] with a library that converts text to the proper format for Barcode readers.That's fine, however, when I draw it to the panel, that's where things stop being fine:But, here's where things get funky. When I put it into a TextBox instead of drawing it via Graphics.DrawString(), everything is peachy:In fact, the TextBox one looks much better than the Graphics.DrawString() one! Am I doing something wrong?[code]
View 2 Replies
Jun 18, 2009
Delegate Sub UpdateTextHandler(ByVal recbuffpass() As Integer)
Private Sub someSub()
Dim f As frmMain = My.Application.OpenForms("frmMain")
f.Invoke(New UpdateTextHandler(AddressOf f.UpdateTextMethod), New Object() {recbuf})
[code].....
View 2 Replies
Jun 9, 2011
I'm trying to compare two variables of type nullable(of boolean) in VB.NET 2010. One of the variables has a value False and the other is Nothing. Now I was expecting the following expression to evaluate to true, but this is not the case:
Dim var1 as nullable(of boolean) = False
Dim var2 as nullable(of boolean)
var2 = Nothing
[Code].....
Why don't I see my MsgBox? How should I compare two nullables (of boolean)?
View 4 Replies
Mar 23, 2011
I'm trying to use the type Boolean for some parameter.
<AttributeUsage(AttributeTargets.Method, Inherited:=True, AllowMultiple:=False)>
Public Class MyAttribute
Inherits Attribute
[code].....
View 14 Replies
Nov 11, 2010
I want to get a value from an item in a DataRow and I would like to store the result in a Nullable Date field.
I see (in VB) that there appears shared "Field" function on the object System.Data.DataRowExtensions. Here's from the Object Browser:
Public Shared Function Field(Of T)(ByVal row As System.Data.DataRow, ByVal column As System.Data.DataColumn, ByVal version As System.Data.DataRowVersion) As T
Member of System.Data.DataRowExtensions
[Code].....
Does somebody have a better way to move values to and from a datarow into Nullable types?
..OR is there a built-in handy function to do this so I don't have to define my own?
View 1 Replies
Jul 17, 2010
When the datagridview's selection mode is set to "RowSelect", the HitTestInfo Type property only returns column header as the type and not the cell that is being clicked on.Is there a way to keep the selection mode as RowSelect and still detect which cell is being clicked on?
View 9 Replies
Mar 3, 2011
I have the following VB.NET function, for example:
Public Function MyFunction (Of TData) (ByVal InParam As Integer) As TData
End Sub
How do I, in a function, determine if TData is a NULLable Type?
View 3 Replies
May 20, 2009
In the code base I'm working in there have a method that has the signature
Public Sub SetDropDownValue(Of T As Structure)(ByVal target As ListControl, ByVal value As Nullable(Of T))
The method I am writing is passed a parameter of type object.
How can I cast the object into something that can be passed into the SetDropDownValue method?
View 2 Replies
Dec 14, 2006
I have the following VB.NET function, for example:Public Function MyFunction (Of TData) (ByVal InParam As Integer) As TDataEnd Sub
View 5 Replies
Jul 9, 2010
I have a structure that contains another structure. The inner structure is nullable. Now wht I do is something like the following. I create a new instance of the inner structure, set the member variables and assign the whole structure to the inner structure of the parent. But it is giving an error. The assignment is not successful. If I try to peek into the structure in the watch window, it says "property evaluation failed" for the HasValue and Value properties.
Dim testData As List(Of TestData) = Nothing
Dim testData_List1 As New TestData
With testData_List1.commonTestParam
[Code].....
View 1 Replies
Oct 29, 2010
The code I want to work:
<Extension()>
Public Function NValue(Of T)(ByVal value As Nullable(Of T), ByVal DefaultValue As T) As T
Return If(value.HasValue, value.Value, DefaultValue)
[code].....
View 2 Replies
May 27, 2009
Why does this give variable A the value of zero (instead of setting it to nothing)?Dim A as double? A=If(2<3, Nothing, 6)
View 11 Replies
Aug 30, 2011
When using the If operator [URL] to assign a value to a System.Nullable object, if the result is Nothing (null), then 0 is assigned to the object. Example: 'Expected value is null (Nothing). Actual value assigned is 0. Dim x As System.Nullable(Of Integer) = If(1 = 0, 1, Nothing) If x is a nullable type, why is it being assigned the default integer type of 0. Shouldn't it receive a value of null?
View 2 Replies
Jan 16, 2012
I'm trying to check if a variable has been defined as a nullable Guid. eg.
Dim myGuid As Nullable(Of Guid) or Dim myGuid As Guid?
It seems doing a myGuid.GetType returns the underlying type, that is type Guid, not Guid?. So testing myGuid.GetType Is GetType(Guid?) always returns False.How do I find out if myGuid is a nullable type?
Ed: I can do the following, which correctly returns True for "Guid?" and False for "Guid":
Not Nullable.GetUnderlyingType(GetType(Guid?)) Is Nothing
The problem is that I don't know how to retrieve the nullable type from the variable itself, in order to test it. I've only been able to get the underlying (non-nullable) system type.
I've written a db helper function. I pass it an object comprised of public members, representing the row data of a table. The members are the table columns.Using reflection, I loop through these public members to create an INSERT statement for a command object and populate its parameters with the values in those members. So far so good.But now there's a table which has a uniqueidentifier column which I must not populate from the row object, as it defaults to "NEWID()" (using SQL Server 2008). Instead of skipping all Guid columns, which would be easy, I only want to skip ones defined in the row data class as "Guid" (non-nullable).Basically, I'm using the Guid? (Nullable) type to indicate it's ok to populate that uniqueidentifier column with data. If it's non-nullable, that tells me to skip it because the column has a NEWID() default value.
View 3 Replies
Jul 7, 2010
I have data source and table that I can bind to my controls and datagridview. I can add records to data table and i can view on datagridview but I can't update and Delete records using datagrid. I have following code.[code]
View 1 Replies
May 15, 2011
I have the following POCO:
Public Class T1
<Required()>
<MaxLength(128)>
<Key(), Column(Order:=0)>
Property K1 As String
[Code]...
I would expect C2 to be created as Nullable, but both C1 and C2 are Not Null. Adding
<Required(AllowEmptyStrings:=True)>
Does not make a difference, as it seems the decoration is aimed at data validation, not DB creation.
So how do i get a nullable column with Code First?
View 1 Replies
Sep 26, 2010
that i can get a message box containing thitems who have the first letter i asked in a textbox , and the items are in a list box. So I repeat, i have alist box, i havetems in it, and i have a text boxupper that i wrote a letter in, and i want that when i click on the button under, it shows me the items in the list boxhat begin with the letter I enteredn the text box
View 1 Replies
