I've been pulling my hair out for awhile on this one, essentially I'm trying to implement a generic repository factory, which is called as follows:
var resposFactory = new RepositoryFactory<IRepository<Document>>();
The repository factory looks like the following:
public class RepositoryFactory<T> : IRepositoryFactory<T>
{
public T GetRepository(Guid listGuid,
IEnumerable<FieldToEntityPropertyMapper> fieldMappings)
{
Assembly callingAssembly = Assembly.GetExecutingAssembly();
Type[] typesInThisAssembly = callingAssembly.GetTypes();
Type genericBase = typeof (T).GetGenericTypeDefinition();
Type tempType = (
from type in typesInThisAssembly
from intface in type.GetInterfaces()
where intface.IsGenericType
where intface.GetGenericTypeDefinition() == genericBase
where type.GetConstructor(Type.EmptyTypes) != null
select type)
.FirstOrDefault();
if (tempType != null)
{
Type newType = tempType.MakeGenericType(typeof(T));
ConstructorInfo[] c = newType.GetConstructors();
return (T)c[0].Invoke(new object[] { listGuid, fieldMappings });
}
}
}
When I try to call the GetRespository function the following line fails
Type newType = tempType.MakeGenericType(typeof(T));
The error I get is :
ArgumentException - GenericArguments[0], 'Framework.Repositories.IRepository`1[Apps.Documents.Entities.PerpetualDocument]', on 'Framework.Repositories.DocumentLibraryRepository`1[T]' violates the constraint of type 'T'.
Any ideas on what's going wrong here?
EDIT:
The implementation of the repository is as follows:
public class DocumentLibraryRepository<T> : IRepository<T>
where T : class, new()
{
public DocumentLibraryRepository(Guid listGuid, IEnumerable<IFieldToEntityPropertyMapper> fieldMappings)
{
...
}
...
}
And the IRepository looks like:
public interface IRepository<T> where T : class
{
void Add(T entity);
void Remove(T entity);
void Update(T entity);
T FindById(int entityId);
IEnumerable<T> Find(string camlQuery);
IEnumerable<T> All();
}
Your code tries to create an instance of DocumentLibraryRepository<IRepository<Document>>
instead of DocumentLibraryRepository<Document>
.
You want to use this code instead:
var genericArgument = typeof(T).GetGenericArguments().FirstOrDefault();
if (tempType != null && genericArgument != null)
{
Type newType = tempType.MakeGenericType(genericArgument);