if a class has a private constructor then it cant be instantiated. so, if i dont want my class to be instantiated and still use it, then i can make it static. what is the use of a private constructor? Also its used in singleton class, except that, is there any othe use ? (Note : The reason i am excuding the singleton case above is because I dont understand why do we need a singleton at all ? when there is a static class availble.
View 8 Replies
Is declaring a constructor private or declaring a class sealed is same thing?
View 1 RepliesWhat is another name of Constructor?
View 3 RepliesI am confused about the constructor of ObjectContext
// Summary:
// Initializes a new instance of the System.Data.Objects.ObjectContext class
// with a given connection string and entity container name.
//
// Parameters:
// connectionString:
// The connection string, which also provides access to the metadata information.
//
// defaultContainerName:
// The name of the default entity container. When the defaultContainerName is
// set through this method, the property becomes read-only.
protected ObjectContext(string connectionString, string defaultContainerName);
I am not understanding the parameters clearly.
I have a connection string defined in my web.config like:
<connectionStrings>
<add name="LibraryConnectionString" connectionString="Server=.SQLEXPRESS3;Database=Library;Integrated Security=true" />
Well...lI do not understand why when i drag-and-drop tables into a new DataClasses dbml it does not construct a default constructor specifying the connection string. I only have constructor with params like:
public DataClassesDataContext(string connection) :
base(connection, mappingSource)
{
OnCreated();
}
I do need a default constructor for LinqDataSource..
I have the following constrcutors within a Model and I want to click the create button on a previous view and pass the projectID in and call the second Constructor so I have the projectID on this view. Do I need to change the routing in someway to call the constructor with the parameter? -
[Code]....
I'm using Microsoft Unity. I have an interface ICustomerService and its implementation CustomerService. I can register them for the Unity container using the following code:
container.RegisterType<ICustomerService, CustomerService>(new TransientLifetimeManager());
If CustomerService has a certain parameter in its constructor (e.g. ISomeService1), I use the following code (I need to specify SomeService1):
container.RegisterType<ICustomerService, CustomerService>(new TransientLifetimeManager(), new InjectionConstructor(new SomeService1()));
No problems here. The problem appears when CustomerService class has two parameters (not one param as in the previous example) in its constructor (e.g. ISomeService1 and ISomeService2). It works fine when I'm using the following code: container.RegisterType(new TransientLifetimeManager(), new InjectionConstructor(new SomeService1(), new SomeService2()));The problem is that I do not want specify SomeService2() for the second parameter. I want to specify only first parameter - SomeService1(). But I get the error that I need to specify none or both of parameters. How can I specify only first parameter of constructor?
I've created a web service , which can a method to set the user credential using Microsoft.Web.Services3.WebServicesClientProtocol. The sample code is :
<WebMethod()> _
Public Sub ClientCredential1(Of TSecurityToken As SecurityToken)_
(ByVal UserCred As Microsoft.Web.Services3.Security.Tokens.UsernameToken)
[code]....
When I run the web service it gives this error: "Microsoft.Web.Services3.Security.Tokens.UsernameToken cannot be serialized because it does not have a parameterless constructor."
I have a Class called Repository for accessing (Read/Write to and from) Database.The projects that require access to the database create an object of Repository and pass the connection string as a constructor parameter for the repository to work for that particular project.
I have few methods in the Repository that i want to be available only if certain connection strings are passed. I don't want them to be available if some different connection string is passed.Is there any way I can accomplish that?I have never used method header technique, if yes, how can i use it? if no, please let me know if there is any other way to achieve my goal.
I'm very new to Visual Studio and I am getting this error when trying to update an Oracle table from Gridview using a tableadapter datasource. I've followed the instructions in my text very closely but am at a loss as to why this error is occurring.
Details: System.MissingMethodException: No parameterless constructor defined for this object.
Source Error:
[Code]....
Stack Trace:
[Code]....
this is the stack trace error I am getting. At this point, I'm a little clueless how to resolve it.
I am doing Music Store sample application.Here my code.
StoreViewModel
[Code]....
StoreController
[Code]....
Create.aspx
[Code]....
But when i click Save it show Error
Server Error in '/' Application.
No parameterless constructor defined for this object.
when we declared as static then we will not create the object to call the static method. then my doubt is how is call the static constructor after creating the object?can you explain cleary?
View 1 RepliesWhat's the best way to handle exceptions that happen from within a controller's constructor?
All I can think of to do is use Application_OnError() or put a try/catch in my ControllerFactory.
Neither of these solutions seem ideal. Application_OnError is to broad - I have some non-mvc content in the site that has its own error handling. Using a try/catch block seems kinda hacky.
If I'm serving different content type -html/text/json/rss.... I would like to be able to handle the exception from within the action method instead of having to write all kinds of conditions to determine what kind of error message to serve.
I just struck upon a prime opportunity to further exhibit my MVC ignorance, by way of the following: How can one make use of a custom view model class that has parameters in the constructor? For example, a class that could intitialize various collections/properties based on an IPrincipal object passed in. I've come across several allusions to this scenario, involving a class inheriting DefaultModelBinder which overrides the CreateModel method, but have yet to find an example.
[Code]....
I receive the error "No parameterless constructor defined for this object", I have read some post on this forum about this error, but i cannot get it to work.
ViewModel
[Code]....
Controller:
[Code]....
[Code]....
First I incorrectly had my node defined in /shared/web.config instead of the web.config in the root of the WebUI project. I also had not correctly defined my connection string within web.config. I have pasted the proper web.config sections below:
[code]....
I am having a constructor on my user control From a main page I just reinitialize the user control.
I tried
[code]....
BtnAdd is the (aspx button runat server) control I want to disable.
While compiling it does not shows error.But while runtime It throws error saying btnAddis null.
when does the constructor on a page in asp.net page lifecycle get called?
View 1 RepliesI have a common base class from which all my ASMX webservice classes will inherit. In the constructor, I want to do some common authentication checks; if they fail, I would like to halt processing right away (subclass's code would not get executed) and return a 401-status-code response to the caller.
However, the common ASPX-like ways of doing this don't seem to work:
Context.Response.End(); always kicks back a ThreadAborted exception to the caller, within a 500-status-code response. Even if I explicitly set Context.Response.StatusCode = 401 before calling End(), it is ignored. The result is still a 500-response, and the message is always "thread-aborted-exception". MSDN suggests I use HttpContext.Current.ApplicationInstance.CompleteRequest() instead. However, this does not stop downstream processing: my subclass's functions are still executed as if the constructor had done nothing. (Kind of defeats the purpose of checking authorization in the constructor.) I can throw a new HttpException. This is a little better in that it does prevent downstream processing, and at least it gives me control over the exception Message returned to the caller. However, it isn't perfect in that the response is still always a 500. I can define a DoProcessing instance var, and set it to true/false within the constructor. Then have every single WebMethod in every single subclass wrap its functionality within an if (DoProcessing) block... but let's face it, that's hideous!
Is there a better / more thorough way to implement this sort of functionality, so it is common to all my ASMX classes?
edit: Accepting John's answer, as it is probably the best approach. However, due to client reluctance to adopt additional 3rd-party code, and some degree of FUD with AOP, we didn't take that approach. We ended up going with option #3 above, as it seemed to strike the best balance between speed-of-implementation and flexibility, and still fulfill the requirements.
I have a [BeastAuthenticate] attribute on my controller. The following code works fine but I would like to use Contructor (Dependency) Injection with Unity. The problem is that the attribute will run the contructor with no parameters. terfaces ITMSLogger and IADGroups are setup to use Dependency Injection with TMSLogger and ADGroups respectively. The following code works fine but doesn't use dependency injection for class ADGroups.
[Code]....
I tried the following but I'm getting an error ("Object reference is required...") with "this (adGroups).
[Code]....
I've set up a strongly-typed View and a controller method to save the object represented in that View. The object in question is from a class that uses named parameters with default values. This is not a database object, but rather is the intermediate object that is used for the display and user input. It gets translated into a database object in the service class. Anyway, when I attempt to save the object, I get the following error:
System.MissingMethodException: No parameterless constructor defined for this object.
This is kind of aggravating. I can add a parameterless constructor to the class, and then everything works just fine. I just don't understand why it is necessary. I'm new to named parameters with default values, but the reading and such that I've done has described that method calls with default values do not have to have a 'no-parameter' implementation. You can just call the method with any or none of the parameters specified and everything works as expected. If there is a 'no-parameter' implementation and no params are passed, then that one is used, since it is more specific than the one with default values. Is the behavior somehow different when this is used in the constructor of a class? Why would I have to include a parameterless constructor when I have all the values accounted for? Is the runtime creating an object on the fly as the save method executes, which requires this? The method is like this:
[Code]....
I'm wondering if the object is instantiated by the runtime in order to populate the method parameter, and then assigned values from the form collection. I suppose that would make sense, but I do not understand why this causes an exception. For what reason would a parameterless constructor be required?
I have an ASP.NET webform where I initialize an array with a list of controls on the page like this
FileUpload[4] = new FileUpload[4];
public myclass()
{
fileUpload[0] = FileUpload1;
fileUpload[0] = FileUpload2;
...etc
}
I then use these in the page load and they are all null. they are null in the constructor but why should they be null when used in the page load.
I have an HTML markup which has HTML Table and Images in it. I am using iTextSharp API to convert the HTML markup to PDF. But, unfortunately the iTextSharp fails to export the HTML markup containing the Images & Table to PDF.
Error: The network path was not found.
using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.text.html;
using System.Data.SqlClient;
using System.Text;
using iTextSharp.text.html.simpleparser;
[Code] ....
I know this error is due the Image Path. But, not able to resolve.
I want to create PDF in a folder and not be able to downloadable to user.
sb.Append(" <table width=100% cellspacing=0 cellpadding=2 class=table1>")
sb.Append(" <div style=text-align: right;>")
sb.Append("<input type=button onClick=window.print() value=Print></input>")
sb.Append("</div>")
sb.Append("<tr><th align=center Cssclass=theadPO style=background-color: #18B5F0><b>Order SHeet</b> </th></tr>")
[Code] ....
Can it handle mapping using private members like NHibernate can? The documentation is very slim, but it seems like one of the objects or methods provided with the tool could do something like this.
Mapper
.With<FooDTO>()
.Map(x => x.Value)
.To<Foo>("_value");
// To<T>(string member) or To<T>(Func<T, bool> func)
Mapper.CreateMap<Foo, FooDTO>();
I know my example methods don't exist as-is, but maybe I've overlooked something else already built in.
