I used to run into problems with this in VB6, too...
If Not ds_Students.Tables(0).Rows(0).Item("ClassDay2").IsNullOrEmpty Then
txtClassDay2.Text = ds_Students.Tables(0).Rows(0).Item("ClassDay2")
End If
This produces "Public member 'IsNullOrEmpty' on type 'DBNull' not found."
And is there a different test for fields of different data types?
I'm encountering a scenario where I need to see if e is "Empty" before I execute code (don't execute if it's Empty).In a routine similar to the following, I can see while debugging the code that "e" is empty, but I can't figure out how to test it in the
Private Sub RadioClick(ByVal sender As RadioButton, _
ByVal e As System.EventArgs) _
Handles Radio1.Click, Radio2.Click, Radio3.Click, Radio4.Click
[code]....
For some reason, I'm encountering situations where this event is being raised by clicking anywhere on the form. However, when this happens, e is Empty. If I can test for that, then my bug will go away, but I haven't been able to figure out the syntax.
When listbox is added to by the user a number of empty RTF files are created and saved with a string variable SavePath1,SavePath2 and SavePath3. The user can then add date to 3RichText boxes and save the data. The data can then be cleared from the RichText boxes, anotheraddition to the listbox and fill the RTB and save. I need to trap the RTBs being filled and the clear button being pressed before the data is saved. To do this I need to test for empty files and tell the user the data has not yet been saved.
View 1 RepliesHow to avoid getting empty fields in a databound combo box?
View 2 RepliesI'm trying to add a service company from a vb form to an SQL table. It works as long as I enter something in every field on the form. If not I get a syntax error so I thought I should check that the field values were not null
I've tried to add a sub to check for blanks but it's not working
btw the table will allow nulls for all fields
Private Sub btnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
Try
[Code].....
I have a database with lots of fields, some of which are still empty and are to be filled in at a later stage. Is there any way of writing an IF statement (or any other method) that will allow these empty records to be 'shown' in my textboxes in Visual Studio, without receiving the error:
Conversion from type 'DBNull' to type 'String' is not valid.
I am building a vb.net application for a client, and there is a problem. I am connecting to a mySQL server, and using the UPDATE command to update certain fields to the specified values, however, once I run this code, the fields on the mySQL server turn EMPTY. Here is my code :
Sub updateresidents()
'MAKES NO SENSE; UPDATES EMPTY FIELDS ON mySQL SIDE??!!!!!!!!!!!!!!!!!!
Dim connection As MySqlConnection
[Code]....
How to tell the program that if the field is empty to skip it and go to the next step. I have tried IsEmpty (but it tells me the variable IsEmpty was not declared), I have tried to use different If statements but in most cases I get the message
"Conversion from type 'DBNull' to type 'String' is not valid."
I tried using an integer variable and setting it to
'Test = CStr(dt.Rows(I)("socSecNumber")).Length'.
It works for the first step (which makes sense b/c socSecNumber is never empty), but when I set the 2nd and 3rd ones
(TestFName = CStr(dt.Rows(I)("firstName")).Length TestLName = CStr(dt.Rows(I)("lastName")).Length If TestFName > 0 And TestLName > 0 Then...)
Then I am back to getting the message
'Conversion from type 'DBNull' to type 'String' is not valid'.
I do not know anything about recordset and when I did try to use it it displayed the message something like 'get and set are no longer allowed'.
The entire function is below:
Private Sub BtnCreateLetter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCreateLetter.Click
Dim SSN As String = TxtBxSSN.Text
Dim dt As New DataTable()
[Code] .....
Is it possible to include something in the SELECT from table? Such as:
"SELECT * FROM" & Students & "WHERE" * NOT DBNull
or
I do not know if it is possible to use variables in the SELECT from table code but if it is I thought perhaps could make a variable named FieldContents and pass it to a function that would do something like:
"SELECT * FROM" & Students & "WHERE" * FieldContents LIKE '[A-Z]'
why this code returns the property names as column headers and empty fields?
Dim table As New List(Of SalesPersonClass.SalesPersonClass)
Dim i As Integer
For i = 0 To salesPeople.GetUpperBound(0)
table.Add(salesPeople(i))
Next
dgSalesPeople.DataSource = table
I have a nullable database field of type varchar. I am writing a unit test for a service method that retrieves the value of this field. The service method uses a custom DAL that returns a value of String.Empty if the database field is Null (this is desired behaviour).
[Code]...
I'm looking into adding some unit tests for some classes in my data access layer and I'm looking at an update routine that has no return value.It simply updates a row based on the id you provide at whichever column name you provide.Inside of this method, we collect the parameters and pass them to a helper routine which calls the stored procedure to update the table.Is there a recommended approach for how to do unit testing in such a scenario?
View 4 RepliesI use VS team system 2008. At the moment i need to test some business classes, i have found two kinds testing NUnit and the unit testing provided by the VS team system. what are there differences?
View 1 RepliesI'm building an Active Directory wrapper in VBNET 2.0 (can't use later .NET) in which I have the following:
IUtilisateur
IGroupe
IUniteOrganisation
These interfaces are implemented in internal classes (Friend in VBNET), so that I want to implement a façade in order to instiate each of the interfaces with their internal classes. This will allow the architecture a better flexibility, etc.Now, I want to test these classes (Utilisateur, Groupe, UniteOrganisation) in a different project within the same solution. However, these classes are internal. I would like to be able to instantiate them without going through my façade, but only for these tests, nothing more.
[Code]...
I am currently using the following code to check for the presence of an entry in a table. I choose this code because I thought it was a good idea to use a public function to reduce the amount of code required. It works fine until the field I am checking for contains a ' character. I realise I need to use a parameter like @name but cannot work out how to pass the correct information to the public function. Can someone show me how to amend my existing code so I can use @staffNo.
Imports System.Data.SqlClient
Dim PaddedStaffNo As String
PaddedStaffNo = (TextBox2.Text.PadLeft(4, "0"c))
[code]....
Unit test method that has Public Read Only property, how do I set the public read only property?target.MyReadOnlyProperty = MyObject
View 1 RepliesI'm making a keyboard test that will test to make sure each key, in a specific keyboard layout, is working correctly.
Each key, with the exception of the first, will be disabled by default. I need to have the tester press the first key (Escape) and if it works, disable that key and move on to the next, (F1). This process will repeat until all the keys have tested.
The dilemma I have is figuring out how to test each keystroke, in order, without making a huge nested if statement.
The only method I could think of, at the moment, was to check the Enable property of the control and then check for the correct keystroke. But, again, doing this would make a huge mess.
how to use bit fields (Boolean) in datagridview in visual basic 2010 how to know CheckBox checked state checked or not if CheckBox Checked State = Checked?
View 1 Repliesim trying to empty a datarepeater control because when the user selects the button twice it throws an error about double binding to the same control.i tried setting the datasouce to nothing and stating databindings.clear() but still didnt work?
View 1 RepliesThe data source is an Access 2003 table. I create the table in code and then populate it with 70 rows (each one empty apart from a date field). This unfortunately adds a 71st row (the placeholder for a new table row). Is there a way to stop this row appearing (I don't allow users to add rows anyway, only to edit existing ones, so this final empty row is just untidy and always empty).
Here is the code I use to create the 70 rows:
Conn.Open()
da.Fill(ds)
dsNewRow = ds.Tables(0).NewRow()
[code]....
I'm currently refactoring an old Visual Basic DLL (VB.Net), which stores all of its data in one module called Globaldefinitions as public fields. There are about 200 fields, referenced thousands of times all around the code:
Public Module Globaldefinitons
Public a As Short
...
Public zz10 As Double
[Code]...
I need to change the module into a class with non-shared fields. This means, each and every of these thousands of references needs to reference the instance of that class:
globalDefinitionsInstance.a = 5
How do I go about this efficiently?
Regular expressions operating on the source fall flat. Refactoring tools like Re-Sharper or CodeRush don't seem to offer this functionality. Visual Studio 2010 cannot do it automatically either.
Class Foo
ReadOnly name As String
Public Sub New(name As String, dependentUpon As Foo)
Me.name = name
[code]....
The output of New Bar() is:
Dependent created. Dependent upon nothing.
Independent created. Dependent upon nothing.
It seems fields are initialized in the same order as they appear in the source code, which (a) leads to an unexpected result, and (b) seems a little puzzling, given that one is normally not permitted to read from uninitialized variables in .NET, yet that seems to be working fine above.I would've expected VB.NET to be smart enough to initialize referenced fields first, and only then those that reference it; i.e. I'd have liked to see this output instead:
Independent created. Dependent upon nothing.
Dependent created. Dependent upon Independent.
how to get VB.NET to behave like that instead, without simply having to swap the declaration order of dependent and independent inside class Bar?
I'm trying to create a table in Word using data from a table in Access. There are four fields in the access table that I need. 3 fields are text which I can populate the Word without any issues. However the fourth field is a memo with >255 characters.I'm struggling to come up with the proper code to allow me to populate the Word field with the memo data that has more than 255 characters. The code I have so far is listed below. But when it hits the memo field, it crashes on the line I marked with **. I know it's not text, but I've tried many different field types, but nothing has worked so far.[code]...
View 1 RepliesMy intent is to have the code - on a button.click event - check the Username and Password fields and return an error depending on which is wrong. Or if both are wrong, return a different error message. I've set the username as parts and the password as parts (still learning how to use external authentication). [Code]
View 2 RepliesIf i change any table definition after using the fields on a form VS stalls and doesnt allow to load the form
View 3 RepliesMy program is databound to an access 2007 database. I have a datagridview showing rows as part of my screen and the other part of my screen is texboxes bound to a different table.What I currently have:
1. Date in textbox from one table
2. Age in Datagridview column from another table
I need help with having a calculated date column in the datagridview that will be the textbox date + age (in days) in the datagrid column. I would also need this column to store in my database like any other field also. So if I typed in 2/17/11 into the textbox, and I typed in 2 in the age field, the calculated field would display and store 2/19/2011 in my datagrid and database. My dataset designer won't let me add a date to a string so I'm completely lost. A query calculates it easy in access but when I load the access query in my dataset it doesn't calculate anymore.
VS 2010 [RESOLVED] Caluclated Fields in a Datagrid
View 8 RepliesI have been using VB a fair bit in the past developing a Access Database, recently I wanted to give my front end interface a bit more power so I have started learning VS 2010.
Anyways, I am still using Access for my databases and i am having a bit of trouble working with the data in VS 2010, what i would like is the following:
A way to form a string or integer from a SQL query (from a single field or multiple on that row) assuming the query will always return one row.
Then a way to write string or integer variables back in to db fields.
example:
Dim cn As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|ItemRegisterDB.mdb")
Dim cmd As New OleDb.OleDbCommand With {.Connection = cn, .CommandText = "select * from tblItemregister where ItemID = 1"}
[Code]....
Example = ??? 'What would i need here to copy fields from that row to string?
I want to be able to select multiple files to upload to my FTP server. Everytime i browse for a file i want a new "Browse" button to appear. What i found was:
Dim f As New Button
f.Location = New Point(0, 0)
f.Parent = Me
[code]....
My DateTimePickers are retaining their values from one added record to the next. How do I empty their Value contents after each record is saved?
View 5 RepliesI have a field that I want to check to see if it has a value or not. But my code is not working. I am using:[code]
View 9 Replies