I created a C# data layer using Entity Framework 6 via the Code First From Database wizard which defined all of the C# classes which represent their respective tables.
There was a table that I missed and I'm looking for a way to generate another class to represent the table.
Is there a way to have this class created after the initial wizard has already been run?
The reverse engineer tool is meant to be used once in code first. Once it has been used you would just add the class that represents the table along with the other entities. If you are adding tables in the database after you have used the wizzard then you are not truely using code first. Just add a POCO class to the entities folder the tool generated and model it after the others. Once you have done that you use the package manager console to add-migration which aligns it back with your schema, next you use update-database to push the changes back to SQL Server.
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Hi I'm new to Entity Framework so excuse me if this question seem simple, but I have tried to find an example or question where this is described.
I have built a webApi interface with classes in what I call an eventmodell. The Interface and model is working well to receive stuff. But now I would like to build the CRUD functions to the database with Entity Framework.
I have added an empty code first model, but then I don't now how to generate csdl, msl and ssl files needed to create the database.
I have added Empty EF designer model but have found no way of adding an existing class to the designer.
I have installed EF Power Tools but that didn't help.
You seem to have a misunderstanding on how Code First works as compared to Database First.
There is no designer needed in a Code First approach. You add classes to your model, setup a DbContext and use Migrations to setup, and then at later stages, alter the database structure.
Checkout this tutorial: Getting Started with Entity Framework 6 Code First using MVC 5
I have added added Entity Framework to my project and selected Code first from database when creating my models. But the problem is, i couln't find how find how to update existing models and add new models to my project when i make changes on database.
It is very straightforward. Switch on migrations, change/add you classes, create a migration and update your database. See here for example. There are plenty of other sources.
When you change your DB you can run the EF generation again but it will overwrite the existing files so you will lose any changes. If you want to maintain code outside the generated files then you can use partial classes. Or alternatively just code them by hand after the initial auto generation, it's quick once you get used to it! :)
I have an existing database that I want to generate its POCOs but I want to end up with model classes outside .tt file, without giving partial definition and "auto generated" comment header for each class I want to have a result like I started building POCOs from scratch. Is there a process to get this result ? Regards
I want to regenerate my database and start updating model from POCOs using migrations
Update : After editing Template File (.tt) I could remove the header comment and partial definition. I think I could get my work done manually. Now, I just need to Exclude .tt file and its sub classes from project and then add only my business classes to the project again.
You can use Entity Framework Power Tools Beta 3 extension to generate your pocos. It has an option to reverse Engineer Code First which Generates POCO classes, derived DbContext and Code First mapping for an existing database.
I'm currently involved in a project where we will present data from an external data source to visitors, but we will also provide meta data for the entities/rewrite some of the original data.
The external data source is a SQL Server database which I've created an .edmx file from and I've created an additional, controllable, SQL Server database with it's own .edmx file. But I'm not comfortable with using two entities for what, in my eyes, is one type of data.
Somehow I would like to merge the two data sources into one, and use only one entity class which I could query. Inheritance in LINQ to Entities would be perfect, but I would prefer no to change the .edmx files manually.
As it is now I have to create wrapper classes and populate them manually with the entity classes, or use multiple database queries to fetch the required data which is a big turn off performance wise.
It feels like it have to exist some sort of work around for these problems I'm facing?
You have two options here.
First you can extend the entity framework class by using partial
classes. It will help you avoiding changes to the generated classes.
Second you can use Entity Framework code first, Which i will
recommend as you will have more control on your entities.
We are using the Code-first approach without an Edmx file, its running fine to create database the first time.
But if I am adding new data entities say new class to my database context then it is not able to add that to new table in that database.
Say for example there are two table initially in database.
ex Database : DbTest
Table : Tbl1, Tbl2
Now if I add new table, say class name 'Tbl3', then it should be adding it into the existing database.
Can any one please explain to me with an example how it can be achieved via code first approach?
I have seen mentioned something like Database.SetInitializer(new ........)
What do I need to put in the blank area of the constructor above?
If you look in your database you will see a table called "EdmMetadata" which Entity Framework uses to determine if any changes have been made to your model since the database was created (which it has in your case).
The default behaviour is for an exception to be thrown if the model and database differ. To get different behaviour you will need to use an IDatabaseInitializer<TContext>.
Luckily, Entity Framework ships with some default implementations of this interface:
CreateDatabaseIfNotExists<TContext> - This will create the database if one doesn't already exist.
DropCreateDatabaseAlways<TContext> - This will re-create the database each time your application is run.
DropCreateDatabaseIfModelChanges<TContext> - This will re-create the database if a change is detected in the EdmMetadata table (usually as a result of creating new tables).
You can of course also create your own implementation of this interface by overriding the InitializeDatabase method.
an example of using one of these initialization strategies is shown below:
Database.SetInitializer(
new DropCreateDatabaseIfModelChanges<NameOfYourDbContextClass>())
Think carefully before choosing an initialization strategy as you could end up losing data already entered into the database and this may not be what you want.
The implementations provided by Entity Framework provide a Seed method for loading your database with data so that you can preload your database with default data each time it is created.
This article provides further information.