Disposing of the DbContext Object

I have two separate styles for using the DbContext object. In one style I create the DbContext object when my class is instantiated, either as part of defining a field for my class:

Public Class Customer Repository
  Dim db As New CustomerEntities

Posted by Peter Vogel on 06/18/20180 comments

URL Rewriting vs. HTTP Redirects

As Philip Jaske mentioned in his interview with Becky Nagel, one of the cool things in ASP.NET Core is the ability to rewrite incoming URLs to "fix up" a request. There are lots of reasons to do this, the primary one being that it gives you the flexibility to move server-side resources to new URLs: You just rewrite incoming requests using the old URLs to point to your new URLs.

Posted by Peter Vogel on 06/18/20180 comments

Converting DataTables to JSON

When I started creating Web Services, I was using ADO.NET DataSets to retrieve data and then sending that data to my consumers using XML. Those Web Services are still there, but my consumers now want JSON.

The good news is that I don't have to rewrite my code to return the data in the right format. While I could switch to using SQL Server's new ability to convert query results into JSON, the existing code has that whole "working" feature that people like so much -- I have no desire to replace it.

Posted by Peter Vogel on 05/29/20180 comments

What the Colors for Changed Lines in Visual Studio Mean

If you have change tracking turned on in Visual Studio, then you'll be getting highlights in the right-hand margin of your editor window flagging the condition of lines in the current file. If you're not getting those lines and would like to, then go to Tools | Options | Text Editor and check the Track Changes option.

Posted by Peter Vogel on 05/22/20180 comments

Sealing Methods and Properties

In general, it's considered rude to seal classes because it prevents other developers from extending the class through inheritance. However, when you declare a base class it's considered perfectly acceptable to mark some classes as overridable/virtual ... and to leave some methods unmarked. Those methods left unmarked can not be overridden by derived classes that inherit from the base class. Essentially, the base class developer is saying that these methods are essential to the nature of the class and modifying those methods (or properties, for that matter) would distort the class.

Posted by Peter Vogel on 04/26/20180 comments

Don't Use Enumerables as Numbers

I just read another discussion of Enums in .NET where the author was all excited about the fact that (under the hood) a named, enumerable value is actually stored as a number. There are ways, in both Visual Basic and C#, to use those numeric values.

I'm not going to show you how to do that because it's wrong, wrong, wrong. The point of using enumerated values is to get away from embedding magic numbers in your code and, instead, replace those values with meaningful names. Accessing the numeric value (a textbook example of an "implementation detail") violates the purpose of setting up an enumerated value in the first place.

Posted by Peter Vogel on 04/23/20180 comments

HTTP Protocol: Headers vs. Body

As part of putting together a request to a Web Service, I'm perfectly willing to modify the headers in the request to carry some data rather than put that data in the body of the request. There is a risk here because some proxy servers will strip out any headers they don't recognize. However, in an SSL request, headers are encrypted and, as a result, not visible to proxy services. To ensure that my custom headers aren't stripped out I only use this technique where all requests are traveling over SSL.

Posted by Peter Vogel on 04/16/20180 comments

Object Browser: The World's Worst-Named Tool

So, you know the class you need but you don't know what class library it's in. How do you add the right reference to your project? Object Browser will let you do it in two steps.

Posted by Peter Vogel on 04/05/20180 comments

Inheriting from Generics: Set the Datatype ... Or Not

When you're creating a derived class and your base type is a generic class, you have two choices in implementing your derived class: You can set the type of your derived class or you can make your derived class another generic class.

For example, imagine that you have a class called ReadRepository that accepts a variety of types:

Posted by Peter Vogel on 04/02/20180 comments

Collecting Collections: The Lookup Collection

Every once in a while, I end up with a bunch of collections in memory and need the ability to pick the collection I want by name. For example, I might need a bunch of Customer collections, one for each city where I have a customer.

Furthermore, I'd like to have those collections organized into a larger collection called CityCusts so I can pull out all of the Customers for any specific city.

Posted by Peter Vogel on 03/19/20180 comments

Finding What's Changed in Your Code

You (or someone else) rolled out a new version of an application and it's behaving…oddly. You ask the people involved (or yourself) "What changed?" and the answer you get is "Nothing." This is, of course, not true. Users do this to us all the time though the question we ask is slightly different ("What did you do differently?", "Nothing").

Posted by Peter Vogel on 03/15/20180 comments

Converting Your ASP.NET Web Forms Application to ASP.NET MVC

If you want to build a Web application quickly, do it with ASP.NET Web Forms. However, you have to be willing to give up a lot: client-side coding and Ajax is more awkward in Web Forms than MVC, you won't have as complete control over your HTML/CSS as in MVC, and you'll have to be careful about what code goes into your code-behind file if you want to do automated testing.

Posted by Peter Vogel on 03/12/20180 comments