Connection String For .Net Core application from .Net Standard Entity Framework 6.0

Question

I am a newbie in .Net Core,

I am always using .Net Framework to develop an application (Web App / Web API). I have develop my custom Framework and it already established. my custom framework use Entity Framework 6.0 (DB First) Now, I have assigned to develop Web Api in .Net Core. but still use my custom framework to process the data. on .net core web api I need to assign connection string like web api on .net standard In .Net Standard my Connection string like below

  <connectionStrings>
  <add name="CompanyEntities"
    connectionString="metadata=res://*/CompanyModel.csdl|res://*/CompanyModel.ssdl|res://*/CompanyModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=127.0.0.10;initial catalog=XYZ;persist security info=True;user id=sa;password=zzzxxx123!;multipleactiveresultsets=True;application name=EntityFramework&quot;"
    providerName="System.Data.EntityClient"/>

for application using .Net Standard Framework (WebApp/ WebApi)... there is no Issue with this. it runs normally

but I don't know, how I can set connection string on .Net Core? please help

I have tried connection string like this but failed


    "ConnectionStrings": {
    "CompanyEntities": "Data Source=127.0.0.10;Database=xyz;uid=sa;pwd=zzzxxx123!;MultipleActiveResultSets=true;Integrated Security=False"
  }

this is the error :

Severity Code Description Project File Line Suppression State Error CS0311 The type 'Classes.Model.Data.Library.CompanyEntities' cannot be used as type parameter 'TContext' in the generic type or method 'EntityFrameworkServiceCollectionExtensions.AddDbContext(IServiceCollection, Action, ServiceLifetime, ServiceLifetime)'. There is no implicit reference conversion from 'Clasess.Model.Data.Library.CompanyEntities' to 'Microsoft.EntityFrameworkCore.DbContext'.

and this my dbcontext

 public partial class CompanyEntities : DbContext
{
    public CompanyEntities()
        : base("name=CompanyEntities")
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }

Merna Mustafa · Answer 1 · 2022-01-20T10:23:42.270

0

Try this:

"ConnectionStrings": {
    "CompanyEntities": "Server=yourServerName; Database=xyz;Trusted_Connection=True;"
  },

Note that you need to install the NuGet package for the database provider you want to access.
For example, if you want to use the MS SQL Server database you need to install Microsoft.EntityFrameworkCore.SqlServer NuGet package.
You also need to install NuGet package for EF tools Microsoft.EntityFrameworkCore.Tools

Make sure to add this to your startup.cs:

services.AddDbContext<YourContext>(options => options.UseSqlServer
            (Configuration.GetConnectionString("CompanyEntities")));

Modify your dbcontext as follows:

 public partial class CompanyEntities : DbContext
{
    public CompanyEntities()
    {
    }

    public CompanyEntities(DbContextOptions<CompanyEntities> options)
        : base(options)
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }

Have a look at this tutorial on EF Core

If you want to use EF 6 (not core) in.NET core, this may be useful but personally I didn't use this before.

edited Jan 20 '22 at 10:23

answered Jan 20 '22 at 07:16

Merna Mustafa

1,235
2
10
22

i am sorry, i don't know where i must put that code at startup.cs – farid wahyu Jan 20 '22 at 08:05
put it inside `ConfigureServices(IServiceCollection services)` method – Merna Mustafa Jan 20 '22 at 08:06
it does not work. an error occur at code services.AddDbContext(options => options.UseSqlServer(Configuration.GetConnectionString("CompanyEntities"))); – farid wahyu Jan 20 '22 at 09:08
I have updated my answer. if it didn't help, please provide the error message. – Merna Mustafa Jan 20 '22 at 09:11
i have updated my post. please help.. – farid wahyu Jan 20 '22 at 09:46
I have updated my answer. – Merna Mustafa Jan 20 '22 at 10:11
I already tried like your suggestion, but still does not work.. I don't know why.. uis the reason because I am using the DB first ? – farid wahyu Jan 21 '22 at 03:58
Sorry for the late response. If you want to use EF core for an existing database, then you can refer to [this](https://www.entityframeworktutorial.net/efcore/create-model-for-existing-database-in-ef-core.aspx), otherwise, you need to use `code first`. – Merna Mustafa Jan 23 '22 at 08:14
I am sorry to being late respon too. owwhh i see it mean, are .Net Core cannot use DB first approach ? – farid wahyu Jan 24 '22 at 01:51
You can't use DB first approach with `EF Core` because it does not support Edmx based modeling, but as I mentioned in the answer If you really need the DB first, you can use `EF 6` on `.NET Core` – Merna Mustafa Jan 24 '22 at 08:27

score 0 · Answer 2 · answered Jan 23 '22 at 18:31

0

Try this exact below code in your DBContext class:-

public class CompanyEntities : DbContext
{
    public CompanyEntities (DbContextOptions<CompanyEntities> options)
        : base(options)
    { }

  ...
   
}

Hope now it will resolve your issue.

answered Jan 23 '22 at 18:31

Pritom Sarkar

2,154
3
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Connection String For .Net Core application from .Net Standard Entity Framework 6.0

2 Answers2