[英]Entity Framework Core: How to dynamically get the DbSet from a derived Type?
I have the following abstract class, named Sector
: 我有以下抽象类,名为
Sector
:
public abstract class Sector
{
public string ID {get; set;}
public string Name {get; set;}
public Sector(){}
}
And a second class, GICSSector
, wich inherits from Sector
: 第二类
GICSSector
继承自Sector
:
public class GICSSector: Sector
{
public virtual ICollection<GICSIndustryGroup> IndustryGroups {get; set;}
}
I have the following DbSet
in my DbContext
: 我的
DbSet
中有以下DbContext
:
public DbSet<GICSSector> GICSSectors {get; set;}
I am trying to write a generic method to loads data from a CSV file, create the objects on the fly and then store the objects in my SQLLite database: 我正在尝试编写一种通用方法来从CSV文件加载数据,动态创建对象,然后将这些对象存储在我的SQLLite数据库中:
public static void UpdateEntitiesFromCSV<T>(MyContextFactory factory, string fileName) where T : class
{
var entities = new List<T>();
// ... Load entities from the CSV
// ... Create the objects and add them to the list
// Add the objects to the database
using (var db = factory.Create(new DbContextFactoryOptions()))
{
var set = db.Set<T>();
foreach(T e in entities)
{
set.Add(e);
}
db.SaveChanges();
}
}
I use the fluent API to manage the tables: 我使用流畅的API来管理表格:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
//...
// GICSSector
modelBuilder.Entity<GICSSector>().HasKey(s => new { s.ID });
modelBuilder.Entity<GICSSector>().Property(s => s.ID).HasMaxLength(2);
modelBuilder.Entity<GICSSector>().Property(s => s.Name).IsRequired();
modelBuilder.Entity<GICSSector>().Property(s => s.Name).HasMaxLength(50);
}
If I run the code I get the following exception: SQLite Error 1: 'no such table: Sectors' . 如果我运行代码,则会收到以下异常: SQLite错误1:'无此类表:Sectors' 。
If I check the type with typeof(T)
or using myEntity.GetType()
I get the same expected result: MyNamespace.GICSSector
如果我使用
typeof(T)
或使用myEntity.GetType()
检查类型, MyNamespace.GICSSector
得到相同的预期结果: MyNamespace.GICSSector
Why EF Core wants to store it in a table called "Sectors" (the base type) and not in the expected GICSSectors? 为什么EF Core要将其存储在名为“ Sectors”(基本类型)的表中,而不是存储在预期的GICSSectors中?
How can I fix it? 我该如何解决?
Note : The method is a generic one that won't be used to handle only classes that inherit from Sector
. 注意 :该方法是一种通用方法,不会仅用于处理从
Sector
继承的类。
Tell EF explicitly what table to use: 明确告知EF使用哪个表:
[Table("GICSSectors")]
public class GICSSector: Sector
{
public virtual ICollection<GICSIndustryGroup> IndustryGroups {get; set;}
}
or use fluent api: 或使用流利的api:
modelBuilder.Entity<GICSSector>().ToTable("GICSSectors");
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