C# - Track Changes Of Object Contained In Dictionary And Change TKey Accordingly
Nov 17, 2010
I am writing a class library to interact with a domain Active Directory. In my object model, I have the following:
Domain;
Organizational Unit;
Group;
User.
In my Domain object, I have an Entries property and an Add() method.
public class Domain {
// The ReadOnlyDictionary<TKey, TValue> is a custom wrapper over an IDictionary.
public ReadOnlyDictionary<string, IDirectoryEntry> Entries { get; }
public void Add(IDirectoryEntry entry) {
Entries.Add(entry.Name, entry);
[Code] .....
For your information, I implemented the INotifyPropertyChanged interface to ease my life, but I don't seem to find a way to make it work the way I want. Perhaps am I not doing things right somehow, as for the location of different methods, I don't know. How can I make my Domain aware of a change that occured within one of its Entries, so that the TKey value is also changed? That is wanted because one could possibly add an entry, change its name meanwhile adding a new entry with the "old" name of the actual within entry, and cause a conflict, etc. In the end, causing the test to fail. But I'd like to make it pass like it actually is. Is there another better approach or workaround?
I created my own Dictionary class, based on the .NET Dictionary. Now I want to overload then Item() Method. This works fine with the following code: Public Overloads Property Item(ByVal key As TKey) As TValue
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] .....
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.
dim l as List(of MyClass) = new List(of MyClass) and I want to get the type of the objects contained in the list, how do I do that? The obvious answer, that doesn't seem to be possible from my actual implementation, would be to do something like this...
public function GetType(byval AList as IList(of GenericType)) as System.Type dim lResult as system.type = nothing if AList.Count > 0 then lResult = AList(0).GetType return lResult end function
But what if the list is empty and I still want to know the type it contains?
I am having some real issues with this one. I have a class which contains two other objects...but I cannot seem to instantiate those sub objects. Here is the code for my class:
I'm trying to setup a WCF web service to be consumed by JavaScript using JSON and jQuery.I've noticed that you can send JSON without a DataContract if the service method parameters match the naming structure of the JSON object:
I have to make a VB project for one of my college Co-Sci classes. However, I am having issues doing what I think is logically possible. Part of our project entails creating a user defined class, then create a form that then instantiates an instance of the object type. After that we are to list the item in a listbox. That is all well and good and works fine.
What I need help with is looping through each object in the listbox, getting some data from the object, then moving to the next.
I have been trying something similar to c++. For example, an object contained in a c++ array can be accessed like this:
array[index].someObjectMethod().
How would someone do something similar to that for objects contained in a VB listbox? I imagine it starts something like this:
how to track an object such as your eyes or a red ball with VB.NET using a webcam or some other video device. I know I have seen a guide to do this, but I can no longer find it.
I can define a NEW sub that runs when an object is instantiated. What is the correct sub to call when it is disposed? I would think a method named dispose, but I seem to remember somewhere that there is a better choice than dispose.
Why do I care? I want to be able to track when a given object is released.
With a form, I can use formClosing, but what about a simple class definition?
how I would know what to search for to have found it without bugging any of you? everything I tried resulted in way too many hits that had nothing to do with VB or what I wanted to achieve.
I'm working on a small project, and ran into an issue. I'm creating new picture boxes on a form to represent a control. My question is how would I code a click event for an object that isn't on the forum initially? Also, how can I keep track of which object is assigned to which data in an array? (IE picturebox 0 is array(0) of data)
I have an officecharge textbox in which I specify how much I'm charging the customer for a specific service. If the user changes the officecharge value for that customer I would like to keep track of the previous value to then compare
it to the new value to then set a boolean variable true or false accordingly. I would like to fire/trigger this segment of code everytime the user leaves the OfficeChargeTextBox (after it loses focus) so that it can compare the final value entered with the previous value and then decide what to do based on whatever login.applies from that point forward.[code...]
I'm attempting to create a customized dictionary object, because I want to add some code to the Add routine, and I can't just inherit because Add is not overridable.
So I'm creating a class that implements IDictionary. Already I am confused, because Dictionary implements a lot of interfaces, listed below:
But IDictionary inherits ICollection and IEnumerable, so why implement all three (and don't they have overlapping methods)?
#2, when I implement IDictionary, the code fills in two Add methods (one for the ICollection add of a keyvaluepair, one for the Idictionary method). Apparently both these add methods are required for Idictionary, yet a regular dictionary (which implements IDictionary) only has one Add method that I can see. I actually would like to have only one Add method if possible. Why am I being asked to make two (and that's before all the other interfaces have been added)?
There a dictionary object that gets loaded with the following key values:
[Code]...
In most situations, life is good and all the individual key values are needed/unique. But in certain situations, the keys with letters behind them (ie...189a, 189b, 189c) all mean the same thing (ie...189). So I need a way to see if a key value exists (like the containskey method) for only the first part of the key and then return true.
I'd like to store a set of key/value pairs in the application settings of my ASP.NET web app, but I'm not finding a straightforward way to do that. For example, these two questions tell me that StringDictionary etc. won't serialize to XML and suggest that I'll have to roll my own implementation. But it seems like this should be easier to do; after all, web.config is XML and < applicationSettings> is essentially a collection of key/value pairs, so it feels like I'm missing something obvious. Given my specific case below, do I really have to roll my own serialization, or is there an easier workaround?
The web app in question is a basic contact form that sends email to different recipients based on the value of a parameter; e.g. [URL]...The goal is to be able add or remove recipients (or change their addresses) by editing the web.config file so that I don't have to recompile and can easily maintain different configurations in test and production environments. For example:
// I can use something like this for the sender address SmtpMsg.From = New MailAddress(My.Settings.EmailSender)
// And then just edit this part of web.config to use different addresses in different environments. <setting name="EmailSender" serializeAs="String"> <value>webcontact@exampledomain.com</value>
I have a VB.NET project where I am able to iterate through the keys and values collections of a dictionary object using an index:
MyDictionary.Keys(idx) MyDictionary.Values(idx)
When this code is taken from the test project and placed into the real project I get the following error:
'System.Collections.Generic.Dictionary(Of Double, String).KeyCollection' cannot be indexed because it has no default property.[code]...
In the line in sub search that says "dtf.Keys(idx) = 0" place your cursor after the right parenthesis and backspace you should get a tooltip that says, "<Extension> ElementAtOrDefault(index as Integer) as Double - index: the zero based element of the index to retrieve.
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.
If I declare my object at the beggining of my page class, and instantiate it in a dropdownlist selected_index change event. Shouldn't this object be available thru out the entire page and also persist thru a postback? I lose the object in my selected date change event in my calendar.
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
