Why do we use the reference of abstract class (or base class) to create object of it's sub-class. eg: TextWriter is the abstract class for StreamWriter & StreamWriter.
Configuration Error Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. Parser Error Message: Cannot create an abstract class.
Source Error:
Line 150: <providers> Line 151: <clear/> Line 152: <add name="NDMSMembershipProvider" type="CSW.Web.Security.NDMSMemberProvider"/> Line 153: </providers> Line 154: </membership>
A instance of a class is created in the partial class of an aspx page.Under page_load or button click method I'm trying to set the value to the class. but when each postback takes place new instance is created and I'm losing the previous value.
public partial class DatabaseSelection : System.Web.UI.Page { DBProperties dbpro; Metadata obmeta; protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { dbpro = new DBProperties(); }
Does anyone have a recommendation how this is archievable? I am trying to pass in the Type to the method and then create an instace of it and then access the properties in it.
I am trying to create instance of class by using reflection in ASP.net web site. Class ClassName is defined and located in App_code folder. Following line returns null, what could be wrong.
Type type = Type.GetType("NameSpace.ClassName", false, true);
From the following URL i got some doubts about the Recommendations for using Abstract class vs interfaces
[URL]
1. If you anticipate creating multiple versions of your component, create an abstract class. Abstract classes provide a simple and easy way to version your components. By updating the base class, all inheriting classes are automatically updated with the change. Interfaces, on the other hand, cannot be changed once created. If a new version of an interface is required, you must create a whole new interface. { Is there any example for this t ounderstand throughly ?} If you are designing small, concise bits of functionality, use interfaces. If you are designing large functional units, use an abstract class. If you want to provide common, implemented functionality among all implementations of your component, use an abstract class. Abstract classes allow you to partially implement your class, whereas interfaces contain no implementation for any members. { Is there any example for this t ounderstand throughly?
I just want to know that how can I utilize the concept of Abstract class, virtual class etc. in my shopping cart website. I have read the tutorial out there on internet and I saw some examples too, but those examples are so general that they dosen't fit into real world scenerio like I am searching for a shopping website. Same questions again and again comes to my mind that why to made a class only to give the declaration of methods and property.
I know what Singleton Pattern means and Abstract class means.What I wanted to know was how would this apply to real world.Could anyone give me any good example or simple explanation.Say I have a simple website, why would I use any of the above if any.Why would it simplify my architechture.
I am developing a couple of small ASP.NET application and would like to know what pattern. approach do you use in your projects.
My projects involve databases, using Data access and Business logic layers.
The data-access approach that I was using so far is the following(I read in some book and liked it):
For DAL layer:
Creating an abstract class that will define all database manipulation methods to implement. The abstract class will contain a static "Instance" property, that will load (if instance == null) an instance (Activator.CreateInstance) of the needed type (a class that implements it).
Creating a classes that implement this abstract class, the implementation will be according to the databases (SQL, mySQL and etc) in use.
With this I can create different implementation according to database in use.
For BLL layer:
A class that encapsulates all all retrieved fields , and static methods that will call the DAL classes.
I am attempting to bind a Repeater (but it could be a GridView or ListView) to a list of objects. The List's type is an abstract type, which has two different classes derived from it, both with different properties. Because they have different properties, I cannot just have one ItemTemplate. If I bind a control to a property of one type of class and the other type doesn't have it, it throws an error.
Here's where I'm at:
I cannot use <% if (whatever) { %> some stuff <% } else { %> some other stuff <% } %> because I cannot access the databound item to make the choice based on its type. I cannot use the <%# %> syntax, which lets me use the databound information, because you cannot code logic like if...then...else. I cannot (rather not) call a function and return a string with the code because what I want to render is complex and contains further nested databound controls. Has anyone found an ingenious way of doing if it is this type of object, display these controls, else display these other controls?
I have a class instance which is created by using Activator.CreateInstance() method. That class instance contains helper methods which are frequently used throughout the application. In order to avoid creating the instance multiple times, I'm just thinking about implementing an appropriate caching mechanism. The following consideration should be taken into account:
1) I can't use static class and methods. 2) There are around 6 instances (1 instance per class) per App Domain.
I am following the Nerd Dinner tutorial as I'm learning ASP.NET MVC, and I am currently on Step 3: Building the Model. One part of this section discusses how to integrate validation and business rule logic with the model classes. All this makes perfect sense. However, in the case of this source code, the author only validates one class: Dinner.
What I am wondering is, say I have multiple classes that need validation (Dinner, Guest, etc). It doesn't seem smart to me to repeatedly write these two methods in the partial class:
[code]....
This doesn't "feel" right, but I wanted to check with SO to get opinions of individuals smarter than me on this. I also tested it out, and it seems that the partial keyword on the OnValidate method is causing problems (understandably so). This doesn't seem possible to fix (but I could very well be wrong).
Suppose we declare and define the variable in one class let say FirstClass and we want to use that variable in another class let say SecondClass which is outside of FirstClass .how to do this?
I have a form with multiple TinyMCE instance. I created the TextArea controls dynamically using a Repeater control - They all have the same ID,but I gave each one a different class. I assigned each of the TextArea controls a TinyMCE instance using the editor_selector : option in the TinyMCE Init function.
I want to refer to a specific TinyMCE instance in a JS function and get its content. In the case when each TextArea control has a different id that could by done by using :
Is there a way to get ref to a specific TinyMCE instance content by the class assigned to it in the editor_selector option of the TinyMCE Init function ?
I've a class that hold all the necessary properties. I want to pass the instance of that class in RedirectToAction. Right now, I can pass the instance but the action to which it redirect, doesn't receive that same instance. The target action has new instance of class.
eg. AbcFilter a = new AbcFilter(); a.ABCname="abc"; RedirectToAction("AbcAction",a); Public ActionResult AbcAction(AbcFilter a) {// this method receives the "a" as new instance, but not the same that I pass in RedirectToAction }
I have a public shared function and I'm trying to access the values of a text box and a session variable.
I'm getting the error "Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class."
Is there any way I can get to the values in the textboxes or session variables from within the method?
I have a class that inherited from object type and has some string properties, also I have a report(.rdcl) that use the fields of that class.I add a webpage in my project, then I drag a reportviewer component into it. then I set the report to my existing report mentioned before using choose report (small arrow). in my page load code behind, I create an instance of that class and now, I don't have any idea how to bind that data.
