user449689 user449689 - 1 month ago 12
C# Question

EF - Extract all record of specific type table per hierarchy

In my EF context I have a hierarchy of classes, managed with the table per hierarchy approach.

Therefore I have a base abstract class and a bunch of classes that derive from it:

public abstract class BaseClass
{
[Required]
public int Id {get; set;}

...
}

public abstract class ExtendedClass1 : BaseClass
{

...

}

public abstract class ExtendedClass2 : BaseClass
{

...

}


The classes are configured as follows:

public class ExtendedClass1Configuration :
EntityTypeConfiguration<ExtendedClass1>
{
...

this.Map(m => m.Requires("Discriminator").HasValue("ExtendedClass1"));
}


To access the database I use a repository that derives from a generic repository:

public abstract class Repository<TEntity> : IRepository<TEntity> where TEntity: BaseClass
{
protected DbContext context;

DbSet<TEntity> GetSet()
{
return this.context.Set<TEntity>();
}

public virtual void Add(TEntity entity)
{
this.GetSet().Add(entity);
}

...
}

public class BaseClassRepository : Repository<BaseClass>, IBaseClassRepository
{

...

}


I want to add a method to my repository that will extract all the classes of a specific subtype (for example all the records of type
ExtendedClass1
).

I have tried some approaches as follows, without success:

public IEnumerable<BaseClass> GetByType(Type type) {
return context.Set<BaseClass>().OfType<type>();
}


This gives me the following compilation error:


The type or namespace name 'type' could not be found


Another approach I'm trying right now is something like this:

public IEnumerable<TBaseClass> GetByType() where TBaseClass : BaseClass {
return context.Set<BaseClass>().OfType<TBaseClass>();
}


What am I doing wrong? How can I implement it?

Answer
public IEnumerable<BaseClass> GetByType(Type type) 
{
    return context.Set<BaseClass>().OfType<type>();
}

Isn't correct, use

public IEnumerable<BaseClass> GetByType<T>() 
{
    return context.Set<BaseClass>().OfType<T>();
}

Typeparams ftw.

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