添加包含到存储库

Question

我有一个可用的存储库。

public class Repository<TEntity> : IRepository<TEntity> where TEntity : class
{
    protected readonly DbContext Context;

    public Repository(DbContext context)
    {
        Context = context;
    }

    public TEntity Get(int id)
    {
        return Context.Set<TEntity>().Find(id);
    }

    public IEnumerable<TEntity> GetAll()
    {
        return Context.Set<TEntity>().ToList();
    }

    public IEnumerable<TEntity> Find(Expression<Func<TEntity, bool>> predicate)
    {
        return Context.Set<TEntity>().Where(predicate);
    }

    public TEntity SingleOrDefault(Expression<Func<TEntity, bool>> predicate)
    {
        return Context.Set<TEntity>().SingleOrDefault(predicate);
    }

    public void Add(TEntity entity)
    {
        Context.Set<TEntity>().Add(entity);
    }

    public void Remove(TEntity entity)
    {
        Context.Set<TEntity>().Remove(entity);
    }
}

正如我在编码存储库中读到的那样，除非真正需要，否则不要添加任何 class。现在，我需要添加 Include。我在这个社区找到了这个 Use Include() method in repository:

public static class IncludeExtension
{
    public static IQueryable<TEntity> Include<TEntity>(this IDbSet<TEntity> dbSet,
                                                   params Expression<Func<TEntity, object>>[] includes)
                                                   where TEntity : class
    {
        IQueryable<TEntity> query = null;
        foreach (var include in includes)
        {
            query = dbSet.Include(include);
        }

        return query ?? dbSet;
    }
}

然后，我将其更改为适合我的代码（如我所想）：

public IEnumerable<TEntity> Include(IDbSet<TEntity> dbSet,
                                    params Expression<Func<TEntity, object>>[] includes)
{
    IEnumerable<TEntity> query = null;
    foreach (var include in includes)
    {
        query = dbSet.Include(include);
    }

    return query ?? dbSet;
}

通过直接访问上下文，我可以写：

Provinces = _cmsDbContext.Provinces.Include(c => c.District).Include(c => c.District.Country).ToList();

但是，有了存储库，我不能写：

Provinces = Currentunitofwork.ProvinceRepository.Include(c => c.District).Include(c => c.District.Country).ToList();

我收到错误：

cannot convert lambda expression to type IDbSet<Province> because it is not a delegate type

请问这里有什么问题

Answer 1

我怀疑您的代码将 lambda 表达式传递给 IDbSet 参数，但无法将其转换为该类型。

我无法测试，但它可以编译，如果该方法是存储库的成员 class 然后试试这个。

public IEnumerable<TEntity> Include(params Expression<Func<TEntity, object>>[] includes)
{
    IDbSet<TEntity> dbSet = Context.Set<TEntity>();

    IEnumerable<TEntity> query = null;
    foreach (var include in includes)
    {
        query = dbSet.Include(include);
    }

    return query ?? dbSet;
}

Answer 2

再次感谢@Adam Carr。

现在是方法代码：

public IQueryable<TEntity> Include(params Expression<Func<TEntity, object>>[] includeExpressions)
{
    IDbSet<TEntity> dbSet = Context.Set<TEntity>();

    IQueryable<TEntity> query = null;
    foreach (var includeExpression in includeExpressions)
    {
        query = dbSet.Include(includeExpression);
    }

    return query ?? dbSet;
}

我改变的是使用 Set 作为方法而不是属性。所以，而不是：

IDbSet<TEntity> dbSet = Context.Set<TEntity>;

我用过：

IDbSet<TEntity> dbSet = Context.Set<TEntity>();

此外，我使用 IQueryable 而不是 IEnumerable。

添加包含到存储库

Add Include to repository

c#

entity-framework

repository

unit-of-work