I have a generic class called SessionManager to control the types of variables I store in session. I have been doing it for String, Integer, List(Of T) without any issues like this.
Public NotInheritable Class SessionManager
'''<remarks>
'''Private constructor to prevent instantiation of, or inheritance from, this class.
[code].....
I would like to do the same for Dictionary(Of T, T). I would like 2 generic private methods for Dictionary(Of T, T) for getting and setting; GetFromSessionAsDictionary and SetInSessionAsDictionary. (When nothing returns empty dictionary like the List(Of T) properties and sets in session) And this should allow me to create as many public properties of Type Dictionary (e.g. Dictionary(Of String, String), Dictionary(Of String, Integer)) as possible to store in session.
EDIT:This is what I have ended up doing after trying to make it generic Dictionary(Of T, T), and it works without any issues. What I want instead is a solution that would not constraint the type to Dictionary(Of String, Integer).
Private Const _Dictionary1OfStringInt As String = "DICTIONARY_1_OF_STRING_INT"
Public Shared Property DictionaryOf As Dictionary(Of String, Integer)
Get
I have created a Dictionary class (MyDictionary for the example). I am currently trying to pass MyDictionary into a function, filter it into a new instance of MyDictionary and pass this new instance into another method. When I am attempting to create the second instance from the filtered first instance of MyDictionary via Lambda Expressions and the ToDictionary Method, I am getting the following error:
Unable to cast object of type 'System.Collections.Generic.Dictionary`2[System.Int32,System.String]' to type 'MyDictionary'. I have simplified the example and recreated it in LINQPad and am getting the same error.
As I am beginner in LINQ, I have small problems. I have dictionary of Char and Long, and I would like to use LINQ to retrieve Char with highest Long Value. I saw some C# samples, which look pretty easy, but I can't achieve such expression in VB.Here are two expressions, and I don't think they are most efficient possible.
I have a mutable class that I'm using as a key to a generic dictionary. Two keys should be equal only if their references are equal. From what I've read, in this case, I don't need to override Equals, GetHashCode , or implement IEqualityComparer.
I have a Generic Dictionary contained or nested as a child in another Generic Dictionary. I need to be able to access the child dictionary objects by key. When I attempt to do this I get the following error: "Value of type 'System.Collections.Generic.KeyValuePair(Of String, String)' cannot be converted to 'System.Collections.Generic.Dictionary(Of String, String)'."
So it seems that the contained Generic Dictionary is being returned as a Generic KeyValuePair when accessed via a key as opposed to iterating through the parent dictionary in a For/Each loop.
The first section of the sample works OK (using a key to access a string value in a dictionary). The second section of the code works OK (iterating through the dictionary values in a For/Each). The third section of the sample is where the error occurs (using a key to access a nested generic dictionary...see underlined code).
Dim td1 As Dictionary(Of String, String) For Each thisKey As String In td1.Keys Debug.Print(td1(thisKey)) Next Dim td2 As Dictionary(Of String, Dictionary(Of String, String)) [Code] .....
If i wish to put items into a System.Collections.Generic.Dictionary, I can either Add or set the Item.I know if you do Add it helps you check if the key already exists and if not it throws an exception.Now I'm curious, so if I'm adding a ton of items, should I prefer setting Item instead of Add since Add does unnecessary checks that may actually slow things down?
Is there any reason to favor one of these approaches over the other when inserting into a generic dictionary with the possibility of a key conflict? I'm building an in-memory version of a static collection so in the case of a conflict it doesn't matter whether the old or new value is used.
If Not mySettings.ContainsKey(key) Then mySettings.Add(key, Value) End If
We have migrated our Vb6 application to VB.NET using a third party tool. Now we are in a process of Refactoring and introducing object oriented concepts in the application.
In VB6, we were using structures in many places. As a part of introducing object oriented programming,
1. is it a good idea of changing all Structures to Classes? or Is there a concept of "Generic Structure" similar to Generic collections, Generic classes?
2. Can some one guide me any source containing guide lines or best practices for applications that are migrated to VB.NET from VB6 and implementing object oriented programmaing.
I want to group items from a linq query under a header, so that for each header I have a list of objects that match the header title. I assumed the solution would be to use ToDictionary to convert the objects, but this allows only one object per "group" (or dictionary key). I assumed I could create the dictionary of type (String, List Of()), but I can't figure out how to write it. As an example I have written a simplified version below.
I am storing a session variable that a user types into a textbox. With their valid input, their session gets created and they get a little more functionality than the regular end users of the site.I was wondering if it is possible to find a way to add someone's session variable to the end of a URL. This way we can email a link to one of our clients, they click it, and their session has automatically begun. They already have the textbox to enter their code into, but I was told that it would be much easier for the users to just click a link that will start their session.
I have created a class with a function in it. I have a collection of data I want to pass back. I tried an arraylist first. Now I am trying to use a dictionary. My problem is that it creates the dictionary ok, but I am only get the last row of data from my
Function GetWeldAuditInfo(ByVal ResourceId As String, ByVal VendorId
countDictionary As Dictionary(of Category, Dictionary(of Date, Integer))
The Class has a Enumeration Property. For the purposes of demonstration, I'll call it MasterCategory.I have been trying to get out an object that looks like the following:
groupedCountDictionary As Dictionary(of MasterCategory, Dictionary(of Date, Integer)
Which results in a IEnumerable (Of Dictionary(of Date, Integer)) for each MasterCategory value.However, I need that IEnumerable of Dictionary flattened to one dictionary with all the integers summed (total counts) for each date. I then tried to use various selects and group bys (from numerous stackoverflow posts) to "flatten" it, but my efforts have fallen short.
Current Code
[Category Class] - MasterCategory As Enum - Name As String etc
On startup of my software which i developed in vb.net, it connects to mssql server. I want to have session id or session number of the connection with mssql. I'm sure it is unique number and i want to use this session in my software for different purposes. My question is
1. is there anything like session id or session unique number when you connection mssql server
I use VS2005 and I have just started working with the dictionary in particular the Dictionary.ContainsKey method. At the bottom of the page in the msdn library it says the following in the community content How to make sure that Contains functions properly.
Public MustInherit Class Column Public ReadOnly Property ReturnSomethingUseful() As Object Get 'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean' cannot override 'Public Overridable Function ParseValue(sValue As String) As Object' because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
I am trying to create a list of a generic type in vb.net 2.0 framework. This is the generic type definition:
Public Class GenericParamMap(Of T) Public Sub New(ByVal pParamName As String, ByVal pPropValue As T) mParamName = pParamName
[Code]....
The compiler does not allow a "T" in the method's parameter because it's not defined, but I'm not sure how or where to define it. I thought it was okay to have a generic method definition.
I am trying to write a generic method, to avoid code duplication, which will create or activate a Form as an MDI children, based on its type. But I have to lines in error (see comments).
I have been using a pretty slick generic invoke method for UI updating from background threads. I forget where I copied it from (converted it to VB.NET from C#), but here it is: Public Sub InvokeControl(Of T As Control)(ByVal Control As t, ByVal Action As Action(Of t))
I have a page, a session starts on page load (using global.asax) the user may not move from (or interact with) that page for a long while and I dont want to increase the session timeout. When the session times out after say.. 20 minutes, I want to start a new one, without moving from the page. I also don't want constant keep-alives i want to do it via another method (timer, button press...)
Partial Class Preferences_MyPreferences Inherits System.Web.UI.Page Dim userID As String = Session("UserID")
This is just a page in asp.net. I want to be able to grab the Session("UserID") but every time I try, I get this error:
Session state can only be used when enableSessionState is set to true, either in a configuration file or in the Page directive. Please also make sure that System.Web.SessionStateModule or a custom session state module is included in the \ section in the application configuration.
If I put that Dim userID inside say the Page_Load Event, then it works fine. Why does it have to be inside an event? I want to dim it once, and use it throughout the page.
I have an 2-d arraylist with 2 fixed columns and dynamic rows. The arraylist will be assigned to the session variable at the end of the code below. My question is how can loop thorugh the arraylist from the session to get its value?
If .SQLDS.Tables(.sSQLDSTbl).Rows.Count > 0 Then Dim NoOfAdjType(1, .SQLDS.Tables(.sSQLDSTbl).Rows.Count - 1) For iRow As Integer = 0 To .SQLDS.Tables(.sSQLDSTbl).Rows.Count - 1
