how to pass dbcontext as a parameter in generic data access layer

Question

I have a generic data access layer implemented by an interface that will be used by different modules with different DB context.

Here is the code:

 public class GenericDataRepository<T> : IGenericDataRepository<T> where T : class
{



    public virtual IList<T> Get(Func<T, bool> filter, int page, int pageSize, string[] includePaths = null, params SortExpression<T>[] sortExpressions)
    {
        List<T> list;
        using (var context = new _DbContext())
        {
            IQueryable<T> dbQuery = context.Set<T>();
            if (includePaths != null)
            {
                for (var i = 0; i < includePaths.Count(); i++)
                {
                    dbQuery = dbQuery.Include(includePaths[i]);
                }
            }
            if (filter != null)
            {
                dbQuery = dbQuery.Where(filter).AsQueryable();
            }
            IOrderedEnumerable<T> orderedQuery = null;
            for (var i = 0; i < sortExpressions.Count(); i++)
            {
                if (i == 0)
                {
                    if (sortExpressions[i].SortDirection == ListSortDirection.Ascending)
                    {
                        orderedQuery = dbQuery.OrderBy(sortExpressions[i].SortBy);
                    }
                    else
                    {
                        orderedQuery = dbQuery.OrderByDescending(sortExpressions[i].SortBy);
                    }
                }
                else
                {
                    if (sortExpressions[i].SortDirection == ListSortDirection.Ascending)
                    {
                        orderedQuery = orderedQuery.ThenBy(sortExpressions[i].SortBy);
                    }
                    else
                    {
                        orderedQuery = orderedQuery.ThenByDescending(sortExpressions[i].SortBy);
                    }
                }
                dbQuery = orderedQuery.AsQueryable();
            }
            dbQuery = dbQuery.Skip(((int)page - 1) * (int)pageSize);
            dbQuery = dbQuery.Take((int)pageSize);

            list = dbQuery
           .ToList<T>();

        }
        return list;

    }
}

In this GenericDataRepository layer, I don't have DB context class. I want this GenericDataRepository to accept DB context as an incoming parameter from different calling module to perform operations written in Getting method.

You can see I use
using (var context = new _DbContext())
In getting method. I don't know how to write GenericDataRepository to accomplish this goal.

this is my interface

 public interface IGenericDataRepository<T> where T : class
{


    IList<T> Get(Func<T, bool> filter, int page, int pageSize, string[] includePaths = null, params SortExpression<T>[] sortExpressions);
       }
 }

Answer 1

Use the dependency inversion principle. Inject a DbContext factory in your class constructor. Create and dispose of the context using the factory instead of accessing the context directly.

Here is a rough sample:

public class GenericDataRepository<T> : IGenericDataRepository<T> where T : class
{
    private readonly Func<DbContext> _contextFactory;
    public GenericDataRepository(Func<DbContext> contextFactory) 
    {
        _contextFactory = contextFactory;
    }

    public virtual IList<T> Get(Func<T, bool> filter, int page, int pageSize, string[] includePaths = null, params SortExpression<T>[] sortExpressions)
    {
        List<T> list;
        using (var context = contextFactory())
        {
             //...
        }
     }
}

Assuming that the layer which is using the generic data repository has access to Dbcontext, they can now instantiate the repository in the following manner:

var repository = new GenericDataRepository<SomeType>(DbContextfactory);
public void DbcontextFactory() 
{
    return new _DbContext();
}