C# - How To Create A Generic/parent Type That You Could Send To Methods Without Having To Define An Overload For Each Type
Mar 5, 2011
I'm trying to create a validation layer that will contain methods to validate all my objects (in my Business Objects layer) .. but when I try to reference both the validation and business objects to each other I get a circular dependency error .. so I've decided to create a new layer (BLL) to validate the objects for me and I'll be able to reference both the validation and the object layers.
so I want to build some kind of class/interface -I don't know what fits more- to be like a generic type or a parent type that my method could accept it as a parameter and check for it's Name/ID property. Instead of defining a new method overload for each object type I have
Simplification
However, when I try to build the control I'm getting the error as shown in the subject. I've tried searching, and it seems the signature for the original function matches the one I have, and all other solutions I've seen uses the same signature.
public static T Sum<T>(this DataTable dt, string columnName) where T : IEnumerable<decimal>, IComparable<decimal>[code]....
It feels like i'm almost there, but not quite :/
Just trying to sum up either decimal or int values in a column in datatable. Currently getting a compile error, however think this is due to the incorrect generic constraint.
I am struggling to find relevant documentation on this, what I basically want to do is to create a 'hyperlink' type and a 'pdf' type that I can put into my XML file and use to link to a webpage or a PDF, with the relevant icon.
I am trying to set property value using reflection as below. I wanted to know if there is any generic way of finding the property type instead of doing it int he below way.
I have a class Trans, with properties siteID and TID. I have a generic list of this class, TransList = list(Of Trans).
Now I want to find the Trans in TransList where the siteID is 3 and the TID is T1. There will only be one record. I want to then update this Trans in the TransList (so I need a reference to the Trans). I am trying to do the following, but it doesnt like it.
In Asp.net Web forms why must a user control be partial? I tried to remove the partial keyword and it says: Missing partial modifier on declaration of type 'test'; another partial declaration of this type exists Where is the other declaration?I am trying to pass a generic type with the user control how can I do that? I can't unless I change the other declaration too. I couldn't find it so I removed the partial keyword.Note: you do have 3 files if your making WebApplication but if your making website you only get 2 files? UserControl.ascx UserControl.ascx.cs so in website where is the other declaration?the reason i want generic is because im making a Grid User Control so i want to pass the type the datasource is going to have.
I'm busy writing a handler to serve various documents for download or presentation in web forms pages. The documents range from various image formats, to PDF, to MS Office documents, to generic binaries. My basic draft of the download process is as below:
[code]....
However, I have some misgivings about lumping all documents together as application/octet-stream, and I would prefer, if feasible, to use a more specific content type per document type. I have a DB table for document types where I could store this. Am I going in the right direction, and if so, where can I find a suitable starting list of content types for document types?
I'm writing a formbuilder for our CMS which dynamically loads bespoke controls into panels within a repeater.
The bespoke controls all inherit from, lets say 5arx.FormBuilder.FormControl, a base class which defines abstract methods for initialising, validating, repopulating, gathering submitted data from them. Controls range from simple text fields to complex, composite client-side controls.
It all works very well, but I've noticed something I feel is anomalous. During the course of writing code to retrieve form controls. gather their data and persist it to my database I noticed that their type reverts to the way objects get typed if you write your code in the (v. irritating) VS 'website project' mode.
So, for example a control that is defined as living in a namespace and being of type
Getting the BaseType property will correctly retrieve the underlying class, but it is perplexing to me why this should be happening. Particularly as I spent much of the summer refactoring our app from its original form as VS Website project (complete with shared code in the App_Code folder and other nastiness) to the (IHMO) correct web application project + supporting claass libraries so that we would have control over our namespaces and not get everything compiled into the ASP.x namespace
EDIT: Modified the (hypothetical) example root namespace.
I have several custom classes that derive from a common base class so they share several members in common. I would like to be able to pass objecs from any of these three classes to a function that will "look at" common properties. However, it seems there is a catch 22 -- When I try to access a member (.FirstName) of the passed object, the computer reports an error that it thinks the member doesn't exist.
It seems to be a sort of contradiction -- since I didn't declare the type, the computer can't confirm existence, but it seems that it should have to take it on faith since the generic character of the type is specified by the code. Possibly there is something I don't know about that would fix this. I'm showing VB code for what I have so far. I went ahead and hardcoded an instance to confirm that the object exists and has the needed property. I commented out the line that had the code that resulted in the computer reporting an error.
Cannot implicitly convert type 'System.Collections.Generic.IEnumerable' to 'hcgames.ObjectClasses.ShoppingCart.ShoppingCartCartAddon'. An explicit conversion exists (are you missing a cast?)
From this query
ShoppingCartItems items = Cart.GetAllItems(); ShoppingCartCartAddons addons = Cart.GetAllAddons(); var stuff = from x in items select new ShoppingCartItem() { ProductID = x.ProductID, Quantity = x.Quantity, Name = x.Name, Price = x.Price, Weight = x.Weight, Addons = (from y in addons where y.ShoppingCartItemID == x.ID select y) };
I have a class constructor which accepts a Listbox.
[Code]....
I need to be able to pass another control type and execute the exact same logic in one of the methods... Seems like a use for Generics... I'm not so sure about the syntax... The type of control that I will pass is a rad combo box which has many of the same properties of the listBox control. However, RadComboBox does not inherit from listBox or dropDown so I am unable to cast. When changing the signature of the constructor to As RadComboBox as well as the property and field the method works as expected. I am trying to avoid duplicating code here.
Now i can populate my gridview trough code by this: //gvwDiensten.DataSource = new BindingList<diensten>(dataManager.GetList<diensten>().ToList());But i would like to use an objectdatasource, so i created this:
[Code]....
</asp:ObjectDataSource>
But when running the page i get:
ObjectDataSource 'dsDiensten' could not find a non-generic method 'GetList' that has no parameters.
Calling Index view is giving me this very very annoying error . Can anybody tell me what to do about it
Error:The model item passed into the dictionary is of type 'System.Collections.Generic.List1[MvcApplication13.Models.Groups]', but this dictionary requires a model item of type 'MvcApplication13.Helpers.PaginatedList1[MvcApplication13.Models.Groups]'.
public ActionResult Index(int? page) { const int pageSize = 10; [code].....
I am developing a C# VS 2008 / SQL Server 2008 website. Although this same code compiles in the Project version, the website version does not compile. Many of their files are the same so I do not understand even where to look. The only compile error I get is:
Could not load type 'DataMatch'
in my DataMatch.aspx file. Is the problem in my web.config file? How do websites differ from projects in VS? All four of these files reside in same directory.
Error parsing attribute 'something': Type 'System.Web.Mvc.ViewPage' does not have a public property named 'something'.
Notice how it tries to use System.Web.Mvc.ViewPage rather than my BaseViewPage class. To make it more interesting, if I remove the "Something" attribute from the Page directive and put some code in the generic version of BaseViewPage (OnInit for example) the class is actually called / used / instantiated.
So, am I doing something wrong or is this a limitation.
I have a FormView that allows a user to register for a company event. I want to do a couple of things with this form.
1. I need to write this data to a MS SQL database
2. I need to send an email confirmation of their registration to their email.
I know how to do both of these things, but i am having trouble doing both at the same time.
It would be nice if I could do it in one click, but I coded it into two pages to try to help simplify it.
The first page allows the user to input their information into a formview and when they click the submit button, it places those answers into session variables:
[Code]....
[Code]....
The Second page confirms the users information by taking those session variables and placing them into labels:
[Code]....
[Code]....
However, after I place information into the formview on the first page, it throws up this error:
"Conversion from type 'TextBox' to type 'String' is not valid".
I have this error "The given value of type String from the data source cannot be converted to type datetime of the specified target column." when I used sqlbulkcopy to do the transaction
