Data Access Layer using Entity Framework

OLE DB Access Data Source using ADO.NET Entity Framework

EF cannot use OLE DB directly because an EF provider have to translate c# into specific SQL syntax (OLE DB is a connection to several DBMSs with several SQL syntaxes)....If you need an EF 6.1 provider for MS Access you can have a look here ...https://jetentityframeworkprovider.codeplex.com/

Using Entity Framework and Metadata to Validate Data Annotation

Change...public class PersonMetaData { [Required(ErrorMessage = "nima", AllowEmptyStrings = false)] public global::System.String ProductName { set; get; } [Range(minimum: 10, maximum: 100, ErrorMessage = "NIIMMMAA")] public global::System.Int32 ProductID { set; get; } } ...to...public class PersonMetaData { [Required(ErrorMessa...

How do you implement a business logic layer when using entity framework as data access layer?

Entity Framework doesn't work really well in a "disconnected" model. Unless something has changed, I've never been able to get it to work great easily....You could use AutoMapper in Layer 2 to create ViewModels to present to Layer 1, but then you'd still have to send the changes back to Layer 3, which could be a pain.

N-Tier Architecture with Service Layer, Business Layer, and Entity Framework

Why are you using dependency injection when you are creating dependencies directly in the service?...public IEnumerable<User> GetAllUsers() { IRepository<User> userRepository = new Repository<User>(dbContext); UserBLL userBLL = new UserBLL(userRepository); return userBLL.GetAllUsers(); } ...Btw. why are you using so many layers when the...

How to map Data Access to Business Logic objects in Entity Framework

If you want to Use Plain Old Clr Objects in your Business Model Design and map them to your database tables, you may use the Code First Approach for Entity Framework. In Code first, nothing will be generated for you. However, you will have the responsability to map your Business Objects to your Database Tables and fields. You can basiscally do it w...

Get multiple data from tables Using Entity Framework data model

You're linking x.id to c.id. I think you need to link x.id_contact to c.id. (same problem for phone & tag)... var data = (from c in db.Contacts from e in db.Emails.Where(x => x.id_contact == c.id).DefaultIfEmpty() from p in db.Phones.Where(x => x.id_contact == c.id).DefaultIfEmpty() ...

Arranging dotnet core app for 3-tiers with data access layer

I think you are looking for the ...Repository... pattern. It a layer between your business and DAL. ...Here's how I organized a recent solution to avoid the UI knowing about my DAL.

How to access the database in Middleware using Entity Framework 6

Consider abstracting the db context behind a service or create one for the db context itself and used by the middleware....public interface IMyLoggingModel : IDisposable { DbSet<Log> Log { get; set; } Task<int> SaveChangesAsync(); //...other needed members. } ...and have the implementation derived from the abstraction....public class M...

Adding "ADO.NET Entity Data Model" uses Entity Framework 6.1.3

Curently (as on writing on 2018-04-23) the EF6 tools are version 6.1.3, the ...last EF6 runtime is 6.2.0.......Where are the EF 6.2 tools for Visual Studio?...We decided that we still needed to complete some work on the tools before we could declare them “final”. However, it did not make sense to delay the release of the runtime packages:..

Entity Framework override SaveChanges() on Service layer instead of Data layer (different projects)

You could fire an event in MyDbContext (maybe it already exists in DbContext?)...public delegate void BeforeSaveChangesSignature (); public class MyDbContext : DbContext { public event BeforeSaveChangesSignature BeforeSaveChanges {get; set;} public override int SaveChanges() { BeforeSaveChanges?.Invoke(); return base.S...