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
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I am building an Ntier application with EntityFramework c#.
I am adding an Entity Data Model in my Data Access Layer with code-first approach from existing database.
Some of the tables of my db weren't included because they don't have primary key. I have seen some ways to work around this problem, modifying EntityFramework's edmx to force the mapping to the database, disguising some field like a key. But I am not using the .edmx, since I can't use automatic migrations with it. I only generate POCOs from my existing database and then go on with code first migrations.
Is there a way to force Entity Framework to generate a POCO for those tables without primary key ? Some only have one entry and really don't need PrimaryKey
In the end, I just wrote my own POCOs for the tables that weren't included.
I used an attribute [KEY] above the property i wanted to act like key. I added DbSet lines in the DataModel and EF did recognize them in my database.
I didn't want to generate primary keys because my boss didn't want, and thats a reason good enough. :) Hope the best for you thx for answer
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 used EntitFramework before to do codefirst with MVC; however, I have never reverse engineered an existing database to get my models.
So what I'd like to do is reverse engineer the existing DB then switch to codefirst so that changes made to the models will be reflected in the database automagically by the Entity Framework gods. How would I do this, specifically the reverse engineer then the switch to codefirst? Please have mercy if this is poorly worded or w/e I'm very new to MVC still.
It basically boils down to using tools to autogenerate the POCO classes that represent your domain, then using those classes as the basis for EF Code First and future migrations.
Here's a msdn article outlining the process
Code First to an Existing Database
You can reverse an existing Database by creating an Entity Data Model.
Check the following link. Here is described step by step the how to reverse a database to a CodeFirst approach with all of the navigation properties and required relationships. This scenario is also very useful for those entity relations that CodeFirst cannot resolve by its own and the configuration in not very intuitive.
Reverse from ModelFirst to CodeFirst
I would like to use a tool to generate C# CodeFirst Entities and Mappings. I have used Entity Framework Power Tools and am looking for a better solution.
Using Entity Framework Power Tools as an example. This allows all tables in a database to be reverse engineered with C# classes generated for each Entity and Mapping. The problem is that you have to generate them all and cannot select just a few.
Is there such a tool that can generate these C# Entities and Mappings for the tables that you select? I do not want to hand-code these C# Code First classes.
If you have an existing database you probably could use model first approach with DbContext templates. Take a look at this walkthrough http://blogs.msdn.com/b/adonet/archive/2011/09/28/ef-4-2-model-amp-database-first-walkthrough.aspx. You can modify your model after creating it from the database. Also, when doing this this blog post may be useful too: http://blog.oneunicorn.com/2012/02/26/dont-use-code-first-by-mistake/
As far as I can tell (correct me if I'm wrong), there are two main approaches to using Entity Framework:
Model First: start with a predefined database and let EF create the code for you.
Code First: write the code, and let EF create the database for you.
I have an existing database and I'd like to write the code myself. Is this "Code Only" approach supported? Does such an approach even make sense in the context of EF?
I disagree with most of the other answers. From what I've seen, the EF "Code First" technology is really just a way to define your model using conventions, annotations, or a fluent mapping definition, rather than an EDMX file. If you write your "Code First" files to mirror your database schema, there is no reason that Entity Framework would be unable to produce the appropriate queries and statements using LINQ to Entities.
For more information, see Scott Guthrie's post on Using EF "Code First" with an existing database.
Entity Framework Power Tools allows you to reverse engineer a database to generate code first like code (that won't re-generate your database). Then you can tweak it from there as you need.
I believe you have to decide what your system of reference is -- the code (Code First) or the database (Model First). If you have an existing database, then go with a Code First approach, it will be hard to keep your changes in synch without generating your model from your code, or your code from your model.
If you have an existing database, but want to extend your model beyond the generated code, you could implement partial classes to accomplish this.
If you want to manually map your EF4 code and your database, you could consider this approach. However, this eliminates some of the benefit of an ORM, which is to set up the mapping for you.
Well I guess you can't have your cake and eat it too in this case - there has to be one definite source on what your model is, it is either the database (DB first), which then generates matching code for you, or the code (Code first) which will then create a matching DB.
The Entity Framework team answered these questions on their blog:
http://blogs.msdn.com/b/adonet/archive/2011/03/07/when-is-code-first-not-code-first.aspx