I am creating a gridview and need to gather the data from various functions that return a type of IEnumerable. I've created gridviews using a dataset as a datasource, but how does one use multiple data sources(of IEnumerable) to populate one gridview? Like how do you combine all that into one dataset?
View 1 RepliesIn C#, when writing a function that returns an IEnumerble<>, you can use yield return to return a single item of the enumeration and yield break; to signify no remaining items. What is the VB.NET syntax for doing the same thing?
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I've searched everywhere for some example code for this, but I can't figure out how to bind data returned from a function that looks like this to a gridview or dataset.
Public Function GetCompanyList() As IEnumerable(Of BusinessUser)
Return (From companyList In CorporateLists
Select companyList.User).Distinct()
[code].....
Planning on migrating from 1.1 to 2.0 framework.After doing the automatic vs 2005 migration, it did highlighted lot of lines: due to unused variables and functions with no return type..Is there a tool which can fix those unused variables plus function with no return types.
View 2 RepliesI have an object called Result<T> that has a constructor which accepts an argument of IEnumerable<T>. I'd like to be able to pass in a datatable if possible.
I tried datatable.AsEnumerable(), but where I bind to the data it was complaining that 'MyProperty' is not a field or property on type 'DataRow' - which makes sense since 'MyProperty' isn't a property on 'DataRow', but it was a column in my datatable.Is there a way to convert a datatable to something that I can pass into the Result object and still have it bind to, say, a gridview?
I want to be able to have the user type in a function, say ,x^2 + 1, and have the computer store this such that it can be recalled and plug in a given value for x. For example, say they type in x+4, the program will then (in a bunch of different text boxes) return the value of x+4 when x = 1, x = 2, and so on up to x = 10. But how can I get it so that it will store x+4, be able to recall it and replace x with it's given value
View 2 RepliesHow to give another function's returned value in LINQ Ienumerable.
Private function GetFruitColor(fruit) as string
'It returns fruit color.
'If valid fruit and color not available, it returns ""(empty string)
[code].....
'Below code is wrong. but please suggest me how to correct it. My intention is, I want output collection(say dictionary) of each fruitname and its color(returned by other function call) for all the fruits which the GetFruitColor is not nothing(it can be empty or valid string).
Dim query = _
fruits.Where(Function(fruit) k= GetFruitColor(fruit) if not k is nothing select fruit, k)
End Sub
I am currently using double data types. The problem I am encountering is that sometimes the user will have to input a value of 0 in the required text box and this creates an error. My question is what data type will allow the user to input 0 and allow the mathematical functions to work properly. Decimals maybe?
View 8 Repliesis there a way to retrieve type T from IEnumerable<T> through reflection?
e.g.
i have a variable IEnumerable<Child> info; i want to retrieve Child's type through reflection
And here is the code that produces the error
CODE:
How can i cast this one?
While learning to use LINQ in VB.NET, I came across the following:Dim x As IEnumerable = (some LINQ query)
If you can't instantiate an interface, but only a concrete implementation of it, why is this allowed? Is there some difference between doing Dim x as (Type) and Dim x as New (Type)?
I'm creating my Data Access Layer and I want to return my object but not all the fields so this is the code i'm using
CODE:
I then call this method in the Business Logic Layer
CODE:
lastly I try to call in in my user interface and bind it to a DataGridView
CODE:
But I keep getting this error: Unable to cast object of type 'System.Data.Linq.DataQuery`1[VB$AnonymousType_0`3[System.String,System.String,System.String]]' to type 'System.Collections.Generic.IEnumerable`1[PP_DAL.DCProposal]'.
The following line is giving me an InvalidCastException when trying to convert to IEnumerable type, even though I have implemented IEnumerable interface. Return New CountryInfo(CountryCodes(i), CountryNames(i)) (also in bold below)
Imports System
Imports Gaia.WebWidgets.HtmlFormatting
Imports System.Collections.Generic
Imports System.Globalization
[code]....
Im writing a data access layer for my application.There are several functions that need to return a list of items like Employee Name, and EmployeeID so it can be bound to a dropdownlist.What would be the proper datatype to return, a Dictionary?The lists only contain 2 columns, a name and id.
View 5 RepliesIs there any particular reason why creating a reference to an object in an IEnumerable Linq query would be really slow? I have a Linq query list consisting of my own objects (count is about 200).I was doing a time-critical task, and this line (which was used a lot in a loop) took nearly a millisecond to execute:
Dim CurObject as MyClass = QueryResult(CurIndex)
I have a table in Oracle that has a column with the Long data type. I create a simple recordset and bind it to a gridview.
Me.grdFollowup.DataSource = rsDataSet
Me.grdFollowup.DataBind()
All of the columns populate correctly except for the Long column. It returns a null for all rows. I have tested the SQL statement in Toad and it works perfectly. how to get an Oracle Long data type to populate in a gridview? This is driving me nuts
In many projects I work on, whenever I have to return a read only collection, I use the IEnumerable<T> interface and make it type specific like so:
CODE:
Most of the time, I return a List but in some functions and read only properties I return an array which also serves the purpose alright by kind courtesy of Extension Methods.
My question is am I violating any design principles by returning IEnumerable<T>s instead of specific types (e.g.: List<T>, HashSet<T>, Stack<T> or Arrays)?
I have a number of text boxs that gather data and put it in a combined string in a rich text box that displays all of the collected data. Some of the text boxes require data pasted from other sources however when that data is then copied from the rich text box to the clipboard through a routine, it loses its formatting. home to maintain the original formating?
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I'm trying to write a program that will take emails that I have saved from outlook as text files and scan it for specific data, and return those strings to a textbox (i will modify it so it outputs the exact way i need it, i just need to grab that info faster than it takes by hand). I dont know how to go about actually grabbing that specific data.
From: Person
Sent: Wednesday, December 03, 2008 10:31 AM
To: Me
Subject: Subject
[code]....
There can be only one grouping (denoted with asterisks, they are separated in the emails like that as well), or 50 and any number in between. I only need the information as shown in the text file example above (sometimes, it is blank or not there - if that's the case just skip and messagebox.show to alert me that it was skipped).
I tried using the linq Zip method on IEnumerable but it does not work for more than 2 arrays.Here is an example in Python of what I am trying to do(I got p - nested IEnumerable - and need q - another nested IEnumerable):
>>> l=['a','b','c']
>>> m=[1,2,3]
>>> n=['x','y','z'][code].......
I have functions in my program that stop after it reaches a Return line but I need the function to continue in case what I want the function to return changes. Is there a workaround for this or a way to force the function to continue after a return?
I made a Test Program to demonstrate the problem. It is a Form that contains only a button.
Here is the source code:
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The messagebox always says "It returned False" when if it continued going through the code like I want it to it would have returned true.
Currently I have been writing subroutines in a activex dll to carry out functions in my main program but I have hit a little snag when trying to return a function when an if statement is triggered. What I want to do is for the dll to check if a function in the my.settings of the main program is true/false and if it turns out that it is true/false in the settings it will trigger the if statement in the dll which will then send data back to the main program - seem simple? I am also wondering, can you transfur boolean settings for enabled textboxes through functions stated in the subroutine of the dll?
View 8 Repliesi have a strange issue today. Sample code is at the below of the post. The code that i have pointed out is too strange. According to my knowledge using return statement the functions return values as byval and copies the value to the stack. Also how can my class can reach outscope elements and change them. Take a look at to the code below. How this could be?
code
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim b As New ByteClass
Dim sumArray As Long = 0
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I have a copy function that I'd like to override in subclasses to return the type of the subclass. Here are my interfaces:
Public Interface IBase(Of T)
Function Copy() As T
End Interface
[Code]....
I have a delegate and its event in C# as below:
public delegate UsernameCredentials UsernameRequiredEventHandler( object sender, string endpoint );
public event UsernameRequiredEventHandler UsernameRequired;
On Converting the above code in VB.Net as follow :
Public Delegate Function UsernameRequiredEventHandler(ByVal sender As Object, ByVal endpoint As String) As UsernameCredentials
Public Event UsernameRequired As UsernameRequiredEventHandler
I am getting error on the above line saying that "Events cannot be declared with a delegate type that has a return type".I understand that this is not supported in VB.Net.
I've just been burned again by the fact that there is no compiler warning when you fail to return a result in a Function that returns a Value type. I wrote the function:
Public Function CompareTo(ByVal other As MessageIndex) As Integer Implements System.IComparable(Of MessageIndex).CompareTo
Me._messageIndex.CompareTo(other._messageIndex)
End Function
which performs the CompareTo Function for two integers, then throws the result away and returns 0, because I forgot to either assign a value to CompareTo, or use Return, and that isn't flagged by the compiler because it's valid VB for a Value type.
I happen never to use "FunctionName = ReturnValue" because it hides information from maintenance programmers and also because I think it's insane .
Is there any way I can get the compiler to issue a warning whenever my Functions are missing a Return, whether it's a Value type or not?
I am trying to create a function to clear my form. The code is as follows:
Private Sub resetForm()
'Set an integer to loop through the controls
Dim x As Integer
[code]....
it works when I set the type of control as textbox but when I try to do the same thing with radioButton and make it's checked proporty = to false I get checked is not a member of 'system.windows.forms.control'
I'm Creating a wrapper dll for my favorite Windows API functions. Normally when windows API calls fail, Nothing happens and you don't know why and this frustrates me. Although you can use their return value to determine If it was successful.
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In this application I need to allow users to enter a month as integer (1-12) then use integer tryparse to validate that input, that seems to be the easy part. I need two create two functions, one that returns the name of the month and the other returns the number of days in that month. The arrays are supposed to be defined and initialized within the function so that the main program can take the user input and call the two functions, then return the appropriate values as output to labels. I am not sure how to declare the arrays in their appropriate functions and then how to call those functions to retrieve the right value from the function.
View 1 RepliesFor each column in data table i want to add parameter with same data type as column data type. But looks it's not that simple.
Dim cmd As New SqlCommand
Dim dType As New System.Data.SqlDbType
For Each cl As DataColumn In DataTable1.Columns
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How can I do this?