Using sets of Entity Framework entities at runtime - entity-framework

Question

I have an EF6 setup against a sql server db with about 60 tables in it.
I have entities for each table. What i'm trying to do is run the same method against a set of these entities that will be known at runtime.
The method is a qa/qc routine that does some data check on particular fields that are assured to be in each table.
I guess what i want to do is make the entity a parameter to the method so i can call it consecutive times.
I would also want to make a set of entities to pass as the parameter.
something like this:
List<string> entList = new List<string>(){"Table1","Table2","Table3"};
foreach (entName in entList)
{
//create an entity with the string name
//call myQAQCMethod with the entity
}
MyQAQCMethod (entity SomeEntity)
{
//run against this entity
doQAQC(SomeEntity);
}
Can this be done? Is it a job for reflection?
EDIT
using (var context = new Context())
{
var results = context.EntityAs.Where(a => a.Prop1 == e.Prop1)
.Where(a => a.Prop2 == e.Prop2)
.Select(a => new
{
APropertyICareAbout = a.Prop1,
AnotherPropertyICareAbout = a.Prop2
}).ToArray();
}
is precisely want i want to do. The thing is I want to avoid typing this loop 60 times. I think i'm looking for a way to "feed" a set of entities to this single method.
Also, thank you very much for helping me. I'm learning a lot.

Answer 1

You need to abstract an interface (entity framework won't even notice):
interface IQaQcable
{
int CommonInt { get; set; }
string CommonString { get; set; }
}
public class EntityA : IQaQcable
{
public int Id { get; set; }
public int CommonInt { get; set; }
public string CommonString { get; set; }
// other properties and relations
}
public class EntityB : IQaQcable
{
public int Id { get; set; }
public int CommonInt { get; set; }
public string CommonString { get; set; }
// other properties and relations
}
// in some unknown utility class
void MyQaQcMethod<T>(T entity) where T : IQaQcable
{
doSomethingWithIQaQcableProperties(entity.CommonInt, entity.CommonString);
}
// in some unknown test class
void Test()
{
var entities = new List<IQaQcable> { new EntityA(), new EntityB() };
foreach (var e in entities)
MyQaQcMethod(e);
}
Now, you could extract a base class from which each derives that actually implements the CommonInt and CommonString properties for each entity needing them, but that can get kind of tricky with Table-Per-Type/Table-Per-Hierarchy, so I'd start with this, and then consider introducing either an abstract or concrete base class as an improvement.
EDIT
Maybe your looking for something simpler than I first thought, based on your last comment.
Let's give ourselves what the DbContext for this might look like:
class Context : DbContext
{
public virtual DbSet<EntityA> EntityAs { get; set; }
public virtual DbSet<EntityB> EntityBs { get; set; }
}
So, it could just be that you wish to do this:
using (var context = new Context())
{
var results = context.EntityAs.Where(a => a.Prop1 == e.Prop1)
.Where(a => a.Prop2 == e.Prop2)
.Select(a => new
{
APropertyICareAbout = a.Prop1,
AnotherPropertyICareAbout = a.Prop2
}).ToArray();
}
Keeping in mind, if there is some set of properties in common across entity classes, you could still do something like the following:
IEnumerable<T> MyQaQcMethod(IQueryable<T> entities, T referenceEntity) where T : IQaQcAble
{
return entities.Where(e => SomePredicate(e, referenceEntity));
}
void Test()
{
using (var context = new Context())
{
// EntityA implements IQaQcAble
var resultsForA = MyQaQcMethod(context.EntityAs, defaultEntity).ToArray();
// so does EntityB, so can call with either
var resultsForB = MyQaQcMethod(context.EntityBs, defaultEntity).ToArray();
}
}
Keep in mind, to avoid modifying the generated entity classes, you could implement the interface members — and the interface — in a separate source file using partial classes. E.g.
// IQaQcAble.cs
internal interface IQaQcAble
{
int CommonInt { get; set; }
string CommonString { get; set; }
}
// a class whose existing property names match the interface
public partial class EntityA : IQaQcAble
{
int IQaQcAble.CommonInt
{
get { return CommonInt; }
set { CommonInt = value; }
}
string IQaQcAble.CommonString
{
get { return CommonString; }
set { CommonString = value; }
}
}
// a class whose property names differ
public partial class EntityB : IQaQcAble
{
int IQaQcAble.CommonInt
{
get { return SomeOtherInt; }
set { SomeOtherInt = value; }
}
string IQaQcAble.CommonString
{
get { return SomeOtherInt.ToString(); }
set { SomeOtherInt = Convert.ToInt32(value); }
}
}