Friday 13 February 2015

POCO classes in Entity FrameWork

POCO :- POCO class is the class which doesn’t depend on any framework specific base class. It is like any other normal .net class that is why it is called “Plain Old CLR Objects” These POCO entities (also known as persistence-ignorant objects) support most of the same LINQ queries as Entity Object derived entities. These classes (POCO classes) implement only the domain business logic of the application.
Some developers use DTOs (Data Transfer Objects) with classes to pass the data b/w layers., Because POCOs are also used to pass data b/w layers ,but they become heavy. So they use DTOs those are also classes.
The main difference b/w DTO and POCO is that DTOs do not contain any methods. They only contain public members. So sending data through DTO is easy because this is lightweight Objects .
The below  code defines a POCO class.

If you want to create POCO classes instead of entity classes or default entity object, then you can create POCO entity classes.
To create POCOs classes first we have to disable auto create classes or auto create code generation, Which generate Context classes entity code in Model1.designer.cs. For disable this code generation right click on model1.edmx( data modal) and  click on property then you will see   the value of ‘Custom Tool’ As ‘EntityModelCodeGenerator ’ you remove this value.

After removing value of “Custom tool” you will se that in modal1.edmx there is no  Model1.designer.cs class means now we have to create properties (Context and Entities ) so for this we have to create POCOs classes.
Now double click on Modal1.edmx and right click on designer surface and click on Code generation Items. There a screen will open from there you select ‘ADO.NET POCO Entity Generator’ and click ‘Add’.

After click on add button you will see 2 classes one is and other is is a context file and is entities file. You can modify this file if you want to generate your template. Model1.Context.cs file has a context class and .cs files under are entity classes.
Entity classes have all properties as "Virtual". Means that these entities fulfil the requirements of POCO Proxy entities . These entities can be used as POCO entities or POCO Proxy entities. By default it will be behave  as POCO Proxy entities, but you can disable proxy creation by setting  a property "ObjectContext.ContextOptions.ProxyCreationEnabled = false".
Important :
  • If you want to write a  unit test for context then replace ObjectSet<> to IObjectSet<>
  • If you are not able to see ‘ADO.NET POCO Entity Generator’ then you install  NuGet package library.


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