I want to convert my code-first project to Database first. Is there an automated way or should I just delete the entities and context code and create a model from the created database?
It appears Entity Framework Power Tools supports a feature called "Reverse Engineer Code-First". You can download it here.
There is no way to convert your code-first classes into database-first classes. Creating the model from the database will create a whole new set of classes, regardless of the presence of your code-first classes.
However, you might not want to delete your code-first classes right away. The entity framework database-first model creates partial classes for all of the entity objects. If you have any business logic (anything besides the plain old properties) in your code-first classes, you can declare them as partial, remove the properties, and maintain the business logic. Essentially, you're letting EF generate the properties in the *Designer.cs file, while you define the business logic in your .cs files.
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Using the Database-First EF model my DTO classes had a clear separation from the actual Database models created by EF. This provisioned a flexible architecture as the DTO and model weren't tightly coupled.
Using Code-First (which I've typically not used as often); I have come across a scenario where when I am adding a migration I get an error:
The Entity Type '[EntityTypeName]' requires a primary key to be defined.
The EntityType in this case is actually defined within one of my DTO classes and isn't intended to be the actual replica of any field in the corresponding Database model. It is a class created to facilitate Serialization data transfer of a JSON object from my API to the database.
But the real question is what concern or relevance is that of EF as it does not specifically relate to the underlying Database Model?
Is there something or someway I can alleviate the error to add my migration? Or is this a default behavior when using the .NET Core Code-First approach that can possibly be disabled? The build of the Solution is fine, it's just EF complaining.
On a .NET application we could auto generate .edmx file from database and can see its diagram by double clicking on that .edmx file. Now my question is since .NET Core does not allow to generate .edmx file then how i can see database diagram visually like the picture bellow? Is there any valid way to do it on .NET Core?
Whats the diff between class diagram and database diagram?
Technically that's a diagram of your Conceptual Model, the Edmx file contains the Conceptual Model, and explicit mapping metadata to map the Conceptual Model to a Storage Model on one side, and an Object Model on the other side. EF has since moved away from the explicit mapping in the .Edmx and uses a combination of Conventions, Fluent Configuration and Class Annotations to generate the mapping at runtime. This is called "Code First", although in practice you often generate a "Code First" model from an existing Database.
In EF6 Code First the Conceptual Model and Storage Model still technically exist, they are just generated at runtime from your Object Model. In EF Core one of the main design goals was to remove the limitations and complexity of this older 3-Model design, and the Conceptual Model (which is what the design surface of an EDMX displays) is gone altogether. No Conceptual Model, no .Edmx, no graphical designer.
I have 20 class.cs with x00s properties for my old project
and now i want to use EntityFramework
but I dont want to rewrite all this classes from begin
i just want to convert this class to DataModel.dbml or use some thing like add Existing Item
and I tried creat class with same name and copy the code inside them but the editor clear them after saving
how can i do that ?
There is plenty of resources regarding Plain Old CLR Objects and Entity Framework code first model on the web.
ADO.NET EF 4.0: Working with Plain Old CLR Objects (POCO) Classes
Code First step by step tutorial
But the gist of it is:
Entity Framework >4.0 supports POCO types that don’t need to inherit from a base class or
implement any interfaces to get persistence. There is also no need for metadata or mapping
attributes on type members, so you can use your existing code as simple entity classes.
An EDMX file that contains the conceptual model is still required. Add a new ADO.NET Entity Data Model to the project.
Using the toolbox, drag entities and associations from the toolbox and design the conceptual model. Simply make sure that the names on your POCO classes match the names of your conceptual entities.
Add entity keys as you would add primary keys in a db. Add associations like foreign keys in a db.
In Solution Explorer, click the EDMX file and then, in the Properties window, clear the Custom Tool property to turn off the automatic generation of .NET classes for your conceptual model.
Right click edmx design area and select 'Generate database from model'. DDL will be produced. Run that to create your db.
Make sure your POCO classes and POCO edmx model are in a separate assembly.
Create your custom ObjectContext derived data context with ObjectSet<T> members like here. Newer EF releases use System.Data.Entity.DbContext and System.Data.Entity.DbSet<T> instead.
You can use dbml too (Linq To Sql classes instead of EF), but you still need to generate your model from scratch, like you'd do with EF.
I have a pre-existing database and Entity Framework 6 database-first model generated from it. I need to create the same database on a different host and/or database engine. I hoped I could use the same model as code-first, but OnModelCreating method of the generated DbContext seems to be protected from being used for code-first approach, it throws UnintentionalCodeFirstException. Generated models don't have any attributes applied too.
Is there any way to reuse my database-first model to create a database with the same schema? Or maybe there's an obvious and much simpler way to do it that I'm missing?
If you just want to create the database you shouldn't need to touch the OnModelCreating method. You should be able to do this from the designer (right click on the designer surface and select "Generate Database From Model" and run the script) or if you want to do this from code do ctx.Database.Create() or use the CreateDatabaseIfNotExists initializer.
I know that I can create the POCO files from .edmx, but this only give's you a part of the code, because if you are going to use code first approach you need to provide more info to the POCO clases for example the key and foreign key by annotations or mapping, Now I was wondering , if exit's some way about how can I created this POCO classes with the annotations from a existing database.
what you are describing is not code first, is database first!
here is the answer you need to check: Entity Framework 4.1 - Code First with existing Database, how to define classes, using Attributes or EntityTypeConfiguration? What is the difference?
the EF power tools can generate pocos fro your db
link