Dynamically access table in EF Core 2.0

by

First you need to get the type of the entity from the name (in case you have the type, just use it directly). You can use reflection for that, but probably the correct way for EF Core is to use FindEntityType method.

Once you have the type, the problem is how to get the corresponding DbSet<T>. EF Core currently does not provide non generic Set(Type) method similar to EF6, mainly because there is no non generic DbSet class. But you can still get the corresponding DbSet<T> as IQueryable by either using some EF Core internals:

using System;
using System.Linq;
using Microsoft.EntityFrameworkCore.Internal;

namespace Microsoft.EntityFrameworkCore
{
    public static partial class CustomExtensions
    {
        public static IQueryable Query(this DbContext context, string entityName) =>
            context.Query(context.Model.FindEntityType(entityName).ClrType);

        public static IQueryable Query(this DbContext context, Type entityType) =>
            (IQueryable)((IDbSetCache)context).GetOrAddSet(context.GetDependencies().SetSource, entityType);
    }
}

or (preferable) invoking the generic Set<T> method via reflection:

using System;
using System.Linq;
using System.Reflection;

namespace Microsoft.EntityFrameworkCore
{
    public static partial class CustomExtensions
    {
        public static IQueryable Query(this DbContext context, string entityName) =>
            context.Query(context.Model.FindEntityType(entityName).ClrType);

        static readonly MethodInfo SetMethod = typeof(DbContext).GetMethod(nameof(DbContext.Set), Type.EmptyTypes);

        public static IQueryable Query(this DbContext context, Type entityType) =>
            (IQueryable)SetMethod.MakeGenericMethod(entityType).Invoke(context, null);
    }
}

In both cases you can use something like this:

db.Query("Namespace.MyTable").Where(...)

or

db.Query(typeof(MyTable)).Where(...)

More Related Contents:

  1. loading a full hierarchy from a self referencing table with EntityFramework.Core
  2. Can’t use Count() in C#
  3. Dynamically change connection string in Asp.Net Core
  4. How to mock an async repository with Entity Framework Core
  5. .Net Core 3.0 possible object cycle was detected which is not supported
  6. .NET Core 2.1 Identity get all users with their associated roles
  7. Cannot access a disposed object in ASP.NET Core when injecting DbContext
  8. How to instantiate a DbContext in EF Core
  9. Command dotnet ef not found
  10. Unable to create migrations after upgrading to ASP.NET Core 2.0
  11. Dynamically changing schema in Entity Framework Core
  12. How to unapply a migration in ASP.NET Core with EF Core
  13. EF CORE 2.1 HasConversion on all properties of type datetime
  14. Is there an Entity Framework 7 Database-First POCO Generator?
  15. How to make EF-Core use a Guid instead of String for its ID/Primary key
  16. The LINQ expression could not be translated and will be evaluated locally
  17. In-memory database doesn’t save data
  18. Avoid or control circular references in Entity Framework Core
  19. EF Core queries all columns in SQL when mapping to object in Select
  20. Unable to edit db entries using EFCore, EntityState.Modified: “Database operation expected to affect 1 row(s) but actually affected 0 row(s).”
  21. Add migration with different assembly
  22. ASP – Core Migrate EF Core SQL DB on Startup
  23. Entity Framework core – Contains is case sensitive or case insensitive?
  24. Entity Framework Core: `SqlNullValueException: Data is Null.` How to troubleshoot?
  25. How to load navigation properties on an IdentityUser with UserManager
  26. How to get user information in DbContext using Net Core
  27. How should I manage DbContext Lifetime in MVC Core?
  28. Implementing recursive property loading in EF Core
  29. How to resolve .net core build error NETDSDK1061 and warning MSB3277
  30. Update-Database command is not working in ASP.Net Core / Entity Framework Core because object in database already exists

Leave a Comment