How to get the actual table name from DbSet in EntityFramework Core 2.0.

#dotnet #netcore #entityframework #efcore20

The way of getting actual table name

For example, if you have DbContext object like this (C#):

public class MyDbContext : DbContext {
    public DbSet<FooBar> FooBars { get; set; }
}
...

var dbContext = new MyDbContext();

You can obtain the actual table name of the DbSet property from the DbContext instance with the following code.

// DbContext knows everything about the model.
var model = dbContext.Model;

// Get all the entity types information contained in the DbContext class, ...
var entityTypes = model.GetEntityTypes();

// ... and get one by entity type information of "FooBars" DbSet property.
var entityTypeOfFooBar = entityTypes.First(t => t.ClrType == typeof(FooBar));

// The entity type information has the actual table name as an annotation!
var tableNameAnnotation = entityTypeOfFooBar.GetAnnotation("Relational:TableName");
var tableNameOfFooBarSet = tableNameAnnotation.Value.ToString();

Package as an extension method

By the way, we can get a DbContext from a DbSet.

Therefore, you can package the above code as an extension method like this C# code:

using System;
using System.Linq;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Infrastructure;

// Prerequire: You have to install DbContextGetter class in this project.
// https://dev.to/j_sakamoto/how-to-get-a-dbcontext-from-a-dbset-in-entityframework-core-c6m

public static class TableNameOfDbSetGetter
{
  public static string GetTableName<T>(this DbSet<T> dbSet) where T: class
  {
    var dbContext = dbSet.GetDbContext();

    var model = dbContext.Model;
    var entityTypes = model.GetEntityTypes();
    var entityType = entityTypes.First(t => t.ClrType == typeof(T));
    var tableNameAnnotation = entityType.GetAnnotation("Relational:TableName");
    var tableName = tableNameAnnotation.Value.ToString();
    return tableName;
  }
}

// How to use:
// 
// class MyDbContext : DbContext {
//    public DbSet<FooBar> FooBars { get; set; }
// }
// ...
// var myContext = new MyDbContext();
// var tableName = myContext.FooBars.GetTableName();
//                                  ~~~~~~~~~~~~~~
// tableName; // -> "FooBars"