Question
I have been assigned a new project and I have decided to give EF a go.In this project all I do is getting data there is no persistence.I have to implement some caching and that's it.
Reading about Repository patterns I have found tons of code samples etc... they seem all wrong to me.They implement a one to one Entity to Repository.
In my project I just need reading data not saving etc... just reading.I have 100s entities I cannot create 100s repository seems all wrong.
I have decided to start simple and I all need is this:
public interface IRepository : IDisposable
{
IEnumerable<T> GetAll<T>() where T : class;
IEnumerable<T> Find<T>(Expression<Func<T, bool>> predicate) where T : class;
T GetOne<T>(Expression<Func<T, bool>> predicate) where T : class;
}
public class Repository : IRepository
{
public IEnumerable<T> GetAll<T>() where T : class
{
return ???.ToArray();
}
public IEnumerable<T> Find<T>(Expression<Func<T, bool>> predicate) where T : class
{
return ???.Where(predicate).ToArray();
}
public T GetOne<T>(Expression<Func<T, bool>> predicate) where T : class
{
return ???.Where(predicate).FirstOrDefault();
}
public void Dispose()
{
throw new NotImplementedException();
}
}
What I am struggling with is where i put the "???" that should be my IdbSet.
How could I Implement my concrete repository?Any suggestions or noddy test sample will do.
many thanks
Accepted Answer
First, you better change the GetAll() and Find() methods to return IQueryable<T> instead of IEnumerable<T>, so that further querying on the dataset would be implemented using Linq-to-Entities.
As of the EF implementation, try something like this:
public class EFRepository : DbContext, IRepository
{
// ctor:
// pass a full connecting-string, or "name=someName" from configuration
public EFRepository(string connectionStringOrName) : base(connectionStringOrName)
{
// init sets
this.Entities1 = this.Set<EntityOfSomeType>();
this.Entities2 = this.Set<EntityOfOtherType>();
}
public IEnumerable<T> GetAll<T>() where T : class
{
return this.Set<T>().ToArray();
}
public IEnumerable<T> Find<T>(Expression<Func<T, bool>> predicate) where T : class
{
return this.Set<T>().Where(predicate).ToArray();
}
public T GetOne<T>(Expression<Func<T, bool>> predicate) where T : class
{
return this.Set<T>.FirstOrDefault(predicate);
}
public void Dispose()
{
base.Dispose();
}
// Your DbSets...
public IDbSet<EntityOfSomeType> Entities1 { get; set; }
public IDbSet<EntityOfAnotherType> Entities2 { get; set; }
}
(I used DbContext with the assumption that you're going code-first)
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