Menu
I recently began using entity framework, and I noticed that generated entities are partial classes. What are the uses of that? I googled a bit and people mostly speak of validation, but I can add validation on the generated entity as well.
206
Partial classes are portions of a class that the compiler can combine to form a complete class. Although you could define two or more partial classes within the same file, the general purpose of a partial class is to allow the splitting of a class definition across multiple files.
Advantages of a partial classYou can separate UI design code and business logic code so that it is easy to read and understand. For example, you are developing a web application using Visual Studio and add a new web form then there are two source files, "aspx. cs" and "aspx. designer.
A partial class is one that can be split among multiple physical files. This feature came in C# 2.0. The partial class break the definition of class two or more than two class files, but it will be together at compile time as one class. Now here we will be using partial concept in MVC using entity framework.
Ordinarily, this means that you cannot override them; you cannot override in one partial class the methods that are defined in another partial definition of the same class. Nevertheless, you can override these methods by setting the Generates Double Derived flag for the domain class.
For the same reason partial classes typically exist at all, code generation.
When code is generated; you don't want your additional methods/properties/whatever blown away, so the designers mark such classes partial to allow users to put additional code in a different file.
In Code-First, the code-generation aspect of EF has largely become obsolete so any EF model classes you create do not need partial.
199
partial is added to generated entities for customization.
In situations when you wish to add your own methods to classes produced by code generators, including EF, it is a good idea to put your implementation in a separate file, so that you wouldn't run the risk of losing your customizations each time the code is re-generated.
Without partial developers wishing to customize the class would have to use work-around techniques, such as applying Generation Gap design pattern.
42
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
