I'm currently working on an ASP.NET project which I've not done before, and I need to use Entity Framework to access a database. I have a database already and following along with this tutorial: https://msdn.microsoft.com/en-gb/data/jj200620
I've managed to get Entity Framework to create the classes for the tables in my database but it has created them all in my Views/Home directory like so:
But from my understanding of MVC these should go in the Models directory? Is it safe to just cut and paste these generated files into Models or am I going to run into problems in the future because it's going to still be trying to use View/Home?
It should be safe to move them to Models. The models are compiled, not deployed as website content, so ASP.NET does not care about their exact location.
You will probably want to update the namespaces of the models, though. I'm guessing that the models were created with a namespace like YourNamespace.Views.Home, and you will want to change it to YourNamespace.Models.
Also make sure to update the namespaces to any references to your models (if you have any). You will get compile errors for any references that you missed EXCEPT for any references in cshtml files.
It would be a lot easier to just delete everything created by EF, and add your ADO.NET Entity Data Model (.edmx file) again into the right folder.
On step 3 of the EF guide in your question, when you add the ADO.NET Entity Data Model, make sure you add it into the Models folder. (Right click on the Models folder, then Add New Item...)
Related
I originally had my EF class in a project added to the solution with my MVC app project referencing that project directly in the solution. I added a bunch of scaffolded items with no issue. I recently moved my EF project to a separate solution and am pulling the dependency with a NuGet package in my MVC app, and now when I go to add a new scaffolded item, the EF class nor the EF models are available to be added.
The existing scaffolded items still function fine and has no issues. What am I missing here?
The scaffolding in MVC is very finicky. In particular, it only works on entity classes that belong to the context and, importantly for you, the context must reside in the same project as where you are running the scaffold. In other words, unless you're building a very basic MVC project, the scaffolding will very quickly become obsolete.
The good news is you don't need it. Unless, you're brand spanking new to MVC development, altering the scaffolded controllers, views, etc. will be far more time-consuming than simply creating everything from scratch. There's nothing magical about any of this. A controller is just a class that inherits from Controller. A view is just a text file with a cshtml extension. Everything else is application-specific anyways, meaning that you would have to touch everything that was scaffolded anyways.
I am trying to implement Database first approach using Entity Framework 5.0 but somehow I am not getting it right. I have the following doubts which needs to be cleared.
1.After adding the Ado.Net Entity Data Model a DBContext class 'Model.Context.cs' gets auto-created in the folder under "Model.Context.tt".
Do i need to add DbContext Generator again?(I have found this recommended by others but i could not make out why!)
2.How to scaffold a controller from the edmx files?
Suppose I have an entity, say A (which I want to scaffold to a controller),having one to many relationship with entity B, where will I define this relationship? In the auto-generated model classes from edmx files or do i create classes A & B and define again and then scaffold Model A?
Any help will be very much appreciated. Thank you
Abhatt:
What t4 templates do is generating classes for you and you need to keep them, unless you decide to use another t4 template.
For instance, you may want to design you database but after that decide to use code first to take advantage of code first approach, in that case after designing the database you will add another t4 template named "EF 5.x DbContext Fluent Generator for C#" and that template creates the poco class and all mappings for you.
Whenever you are adding a controller mvc uses scaffolding to create controller's methods and views. However, if you want to have more control on how to generate them, you may install MVCScaffolding from package manager console. Having MVCScaffolding installed, you will be able to customize t4 templates.
For more info check out MVC Scaffolding project on CodePlex:
http://mvcscaffolding.codeplex.com/
also there is another good one:
http://www.codeproject.com/Articles/468777/Code-First-with-Entity-Framework-5-using-MVC4-and
I find this site is very interesting and very helpful. I came up with this doubt while programming a project in asp.net mvc. I had to remove few columns from a view which I was using to pull data from the database back to my presentation layer. After removing those columns, I build my project and there were no errors. When I ran it, my project broke with error saying missing related columns as Entity was not changed.
But, my question is that is it necessary that every time I need to update my entity model?. What if I deploy my project in production and then had to remove one column from the view? It will be a hell of task for me If I had to update model, build and deploy it back again on production. Is there a simple solution for this?? thanks for your help
You have to update the entity model every time the database structure changes, what you need to do is to decouple the EF model from the MVC project, if you don't what to work with Ioc, a simpler approach whould be to place the EF model in a separate assembly, when the database changes, rebuild the assembly and deploy it on the server, this way you don't need to rebuild the entire MVC.
I've got an ASP.NET MVC 4 site with MSSQL database generated by code first approach. I want to use this database in another project. This project should crawl several tables from db, update them and send notification to users.
What is the best way to add existing database from the first project to the second project? I'm thinking about generating edmx by database, but this approach doesn't seem good enough.
You would be best moving the EF code and Entities into their own library, and then having your two different projects (Web and Windows Service) have a reference to that library.
Then, if and when your database structure or entities change, you only need to do this in one place.
If the second project is not going to modify the structure of the database, then I would use a data-first approach in your second project.
You can use codefirst mapping without problem on existing database. So simple reference assembly with datacontext in other project and it will work. (Don't forget set connection string in config file of other project)
Lets consider default ASP.NET MVC application folder structure, so it's looks like this:
-App_data
-Content
-Controllers
HomeController.cs
-Models
AccountModels.cs
-Scripts
-Views
My question is: Where is the best place to put Entity Framework Data Model (EDMX) file? Is it Models folder? Yes - we know that good solution is to introduce new Project and reference it to MVC application, but lets forget about this now.
For a small project, it should be part of the Model. For a larger product, the repository and the associated model could be in a separate assembly.
Well this is debatable, but i'd vote +1 for the Models folder.
The only other candidate would be App_Data, but this is generally for file-based databases (SQL Server CE .MDF, for example) and files you don't want served by IIS.
As the EDMX is an abstraction of the database, it should go into the Models folder.
If the project gets bigger, you should definetely move your EF Model into another project. To future-proof yourself from this, make your Controllers access the EDMX via Repository/Interfaces, so when you move the DAL over to another project, all you'll have to do is add the reference and add in the using statements.
I would put the EF-model (aka physical model) always in its own assembly or in a "core" assembly outside of main MVC application. The same applies for your business-logic / domain-logic / domain-services / etc. Separate the non-web stuff from the MVC-Web-Application.
This will help you re-use the core part of your app. For example when you need to expose it as a service, a command-line tool, migration-tool, etc.
Because storing this in its own assembly is so easy and takes you a few minutes I highly recommend doing this for each and every tiny app too.
My opinion is that you should create
a separate project for domain objects, datacontracts etc. etc...
Like MyProject.Infrastructure including many folders like
DataContracts, Model, Exceptions etc.
a separate project for DataAccess wich contains the DBContexts and the Repositories, this way you can easily manage migrations later on