如何根据表名称在DbContext中选择正确的DbSet

问题描述：

说我有一个带有以下DbSet的DbContext

Say I have a DbContext with the following DbSets

class Amimals : DbContext
{
    public DbSet<Dog> Dogs { get; set; }
    public DbSet<Cat> Cats { get; set; }
}

在每个EntityTypeConfiguration里面，我为每个DbSet定义表

Inside of each EntityTypeConfiguration I am defining the table for each DbSet like

class DogConfig : EntityTypeConfiguration
{
    public  DogConfig()
    {
        this.ToTable("DOG_TABLE");
        ...
    }
}

现在，如果我有表名和DbContext，该如何获取和使用正确的DbSet?

Now, if I have the table name and the DbContext, how can I grab and use the correct DbSet?

void foo()
{
    string tableName = this.GetTableName();
    using(Animals context = new Animals())
    {
        /* Made up solution */
        DbSet animalContext = context.Where(c => c.TableName == tableName);
        ...
        /* Do something with DbSet */
        ...
    }
}

答

您可以使用方法DbContext.Set(Type entityType)通过Type从DbContext获取DbSet.因此，如果您将模型类名称作为字符串，则应该对实际的clr类型进行一些映射.

You can get DbSet from DbContext by Type using the method DbContext.Set(Type entityType). So if you have the model class name as string you should do some mapping to actual clr type.

例如:

string tableName = "Cat";
var type = Assembly.GetExecutingAssembly()
        .GetTypes()
        .FirstOrDefault(t => t.Name == tableName);

if(type != null)
    DbSet catContext = context.Set(type);

您还可以使用完整程序集合格名称Type.GetType('...')

You also can get type from string using Full Assembly Qualified Name Type.GetType(' ... ')

如果您可以某种方式以通用方式存储配置并使用通用context.Set<T>()方法，将会更加容易.

If will be even easier if you can store configurations somehow in generic way and use the generic context.Set<T>() method.

如何根据表名称在DbContext中选择正确的DbSet

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