Using the wizard, I created a DbContext from an existing database and only selected one table to be pulled in. However now I need to add additional tables from that database to the Entity Model.
What is the easiest way to add more tables from an existing database to a context that I have already created and to also generate the respective models for those tables?
Easiest way is:
1) Open your .edmx database
2) Right click and choose "Update model from database..."
3) check the tables you want and click finish
4) EF will create all your entity classes for you
If you want to add the tables manually to your DbContext, you can do so by adding properties of type DbSet to the DbContext. For ex:
public DbSet<CarColor> CarColors { get; set; }
I think EntityFramework Reverse Poco Generator is what you're searching for.
It's an extension for VS which allows to populate a TT file, then creating POCO entities for you.
It is downloadable here: EntityFramework Reverse Poco Generator
I've wrote a very brief guide you could refer to, in order to setupt the extension and use it for your means. Check it here: Introduction to EntityFramework Reverse POCO Generator for Visual Studio
Related
I have to create some new entities in a new or existing database using Entity Framework that will need to interact with some legacy tables and I'm wondering what the best approach is here. I was hoping to use Code First with migrations.
For example, say I have an existing populated Person table and I need to create a Animal table that will contain a PersonId foreign key to reference the existing people.
As far as I can tell these are my options:
Create a new DBContext (for a new DB) with an DBSet<Animal>, using code first migrations and POCO entity classes. Ran into problems with setting up the foreign key pointing to another DB.
Create a new DBContext (targeting the existing DB) with DBSet<Animal> and create some kind of POCO wrappers around the existing table. I'm not sure if this is possible - I tried something like but when applying the migration EF tried to create the Person table. I assumed this would map to the existing table instead of creating a new one:
[Table("Person")]
public class Person {
Use Database first with the existing DB and create the tables in the existing DB but then I lose out on using POCO and migrations with my new entites.
Are there any better options that I'm missing or should I go ahead with using Database first?
You can use EntityFramework Reverse POCO Code First Generator.
Reverse engineers an existing database and generates Entity Framework
Code First Poco classes, Configuration mappings and DbContext.
This generator was designed to be customisable from the very
beginning, and not fixed and rigid like other generators. Go and play
with the settings in the .tt file, that's what it's there
for.
Here is the link : EntityFramework Reverse POCO Generator
It is possible to generate a POCO class for one selected table in entity framework.
There are few tools that does that, but it does generate for all the table,
The primary reason i am asking this is to generate a POCO class for a single table, and add attributes to it manually, and the all i need to do is to attach it to DbContext as a property :).
As for example using Package-manager, they way it is done to add migration
generate-poco TableName FileName.cs
You can use the ADO.Net wizard to generate the POCO classes for you from the database. The wizard will generate one partial class per table with properties that match your field names. Here is what I've done in the past when I wanted to add a new large table to an existing code first context.
Add->New Item -> ADO.Net Entity Data Model
Move the generated POCO classes to some other folder (and edit the namespace)
Delete the rest of the extra stuff (I.e the .edmx file and generated context)
Add the DBSet to 'your' DBContext
If you are using EF migrations
add-migration
update-database
There are a lot of extensions for visual studio for that.
EF 4.x POCO Entity Generator for C# Free (try this one and you only need to map the table)
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.
Assumptions
Using EF 6.1, MVC 5, VS 2013, C#
I have an existing database model designed in Toad DM for SQL Server and it's very important keep it always updated
Steps and Notes
Using ADO.NET Entity Data Model I chose Code First from Database (new feature in EF 6.1) to generate the models. Note: Model classes and DbContext class generated successfuly but NO .edmx or .tt file was generated.
Next I added a new scaffold item: MVC 5 Controllers with views, using Entity Framework. Note: Success, controllers and views generated
Question
From now on I don't want to use Code First to update my database. Instead I want the models to be updated based on database changes. What to do next? If I don't have an edmx file will I not be able to update my model classes from the database?
The Entity Data Model Wizard's Code First from Database does an excellent job creating your entity classes, as if they were created in the Code First style. What you are asking is if there is any way to keep these classes up-to-date as your database changes, similar to the EDMX style "Update Model From Database". From what I've researched this is not possible using the built-in tooling. However, here is one workaround that I've found useful:
Let's say I have database with a product table and customer table. Originally I created a StoreDBContext class, and selected product as one of my objects. Now I want to add the customer table as a new entity to the existing context. Here's how to do this using the Code First Wizard:
Create a new Entity Data Model, call it StoreDBContextTemp or whatever
Choose the code first from database wizard option
Select customer as an object to add (just customer) & complete the wizard
Open the newly created context file, StoreDBContextTemp.cs, and copy the virtual properties of your newly added entities:
public virtual DbSet<Customer> Customers {get; set;}
Paste these new properties into your Original StoreDBContext.cs dbcontext class.
Delete StoreDBContextTemp.cs, and remove the connection string for StoreDBContextTemp in app.config/web.confg etc.
You can now use Customer on the StoreDBContext class
If you add or remove tables you will need to manually adjust fields, but at least you won't need to hand write dozens of properties each time a new table is added to the model.
One more option is just delete the auto generated classes from the project and once again generate them.
While following this approach only thing we need to make sure that is we should give the same name for the data model(class name which inherits from DbContext ) as the previous one.Data model name is highlighted in below snap
Three things.
There's no .edmx when you use Code First.
If you use Code First Migrations you would have to write first the code and after that migrate the changes to database. This helps you to have much more organized you code with no generated code which is an advantage.
There's a plugin in Visual Studio for doing contrary. Entity Framework PowerTools allows you to select the database and map it to objects.
https://visualstudiogallery.msdn.microsoft.com/72a60b14-1581-4b9b-89f2-846072eff19d
The best solution to me is deleting the model and recreate updated one with the same name, keeping in mind two points:
Personal extension methods implemented for the model;
Possible manual relationships between tables added to the model because of not setted up in the phisical db.
My personal solution:
Move all extension methods to another partial class that won't be overrided;
Insert all added properties of an entity to another partial class;
Keep track of all manual relationships in an help file, so you can add them again being sure not to loose anything;
Delete the old model and recreate one new with the same name and update it with the manual relationships of point 3.
I am delving into the EntityFramework 4 code first of entities approach and I am getting stuck on how to take the ObjectContext / Entities and link them to a database.
I have looked at varous sites on [msdn][1] and [blogs][2] about how to use all of this but they all fail in talking about how to create a database that the entities will be saved in or don't take the code first apprach. I know I can create an edmx file and generate sql from that but since I am writing my entities first this file is empty and through the designer I don't see a way of adding my entities without duplicating effort (in creating all the entities/fields etc).
There does not seem to be the EntityConfiguration class in the full release of entity framework. It appears to be only in the CTP that I am NOT using (a lot of the examples on the web use the CTP).
Also the following context takes strings that in no way seem to relate to the edmx or database.
public class EntityContext : ObjectContext
{
public EntityContext()
: base("name=ExampleEntities", "ExampleEntities")
{
ContextOptions.LazyLoadingEnabled = true;
Users = CreateObjectSet<User>();
}
public IObjectSet<User> Users { get; set; }
}
So the question is.
How do I create a database schema that maps to my entities?
Should I use an edmx file at all or create my own database file (.mdf)?
If I do use the edmx file how do I add my code first entities easily?
How do the ObjectSets within the ObjectContext map to the database?
Thanks
EDIT
I am using VS2010 professional and the classes that come with that. I see CTP4 is out so I assume the RTM version is not out yet. Is this correct?
Add this to your application_start event to create the database:
Database.SetInitializer<YourObjectContextClass>(new RecreateDatabaseIfModelChanges<YourObjectContextClass>());
Looks like I needed CTP4 found here
I also followed the walkthrough