Question

我正在尝试使用条件包含（解释here，但它没有检索子信息。为什么？我想我已经按照所有步骤... 我正在使用WebApi控制器和Visual Studio 2012

我已经检查过了，我为每个房子分配了门类型。这是一对多关系。

我有这个：

DoorType具有此属性

public virtual ICollection<House> Houses{ get; set; }

House拥有此属性

public virtual ICollection<Door> DoorTypes{ get; set; }

我正在查询此方法

public IEnumerable<House> GetList(string latitude, string longitude, string idHousesTypeList)
{
    IEnumerable<int> intIds = null;

    if (!string.IsNullOrEmpty(idHousesTypeList))
    {
        var ids = idHousesTypeList.Split(',');
        intIds = ids.Select(int.Parse);
    }

    var location = DbGeography.FromText(string.Format("POINT ({0} {1})", latitude, longitude), 4326);
    var count = 0;
    var radius = 0.0;
    IEnumerable<House> houses = null;

    while (count < 5 && radius < 500)
    {
        radius += 2.5;
        var radiusLocal = radius;

        var dbquery =
            from house in Uow.Houses.GetAll()
            where house.Location.Distance(location) / 1000 <= radiusLocal
            orderby house.Location.Distance(location)
            select new
            {
                house,
                doorTypes= from doorType in house.DoorTypes
                                where intIds.Contains(doorType.Id)
                                select doorType
            };


        houses = dbquery
        .AsEnumerable()
        .Select(p => p.house);

        count = houses.Count();
    }

    if (houses != null && houses.Any())
    {
        return houses;
    }

    throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.NotFound));
}

我正在使用通用EFRepository

public class EFRepository<T> : IRepository<T> where T : class
{
    public EFRepository(DbContext dbContext)
    {
        if (dbContext == null)
            throw new ArgumentNullException("dbContext");
        DbContext = dbContext;
        DbSet = DbContext.Set<T>();
    }

    protected DbContext DbContext { get; set; }

    protected DbSet<T> DbSet { get; set; }

    public virtual IQueryable<T> GetAll()
    {
        return DbSet;
    }

    public virtual IQueryable<T> GetAllIncluding(params Expression<Func<T, object>>[] includeProperties)
    {
        IQueryable<T> query = DbContext.Set<T>();
        foreach (var includeProperty in includeProperties)
        {
            query = query.Include(includeProperty);
        }

        return query;
    }

    public virtual T GetById(long id)
    {
        return DbSet.Find(id);
    }

    public virtual IQueryable<T> GetByPredicate(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
    {
        IQueryable<T> query = DbContext.Set<T>().Where(predicate);
        return query;
    }

    public virtual IQueryable<T> GetByPredicateIncluding(System.Linq.Expressions.Expression<Func<T, bool>> predicate, params Expression<Func<T, object>>[] includeProperties)
    {
        IQueryable<T> query = DbContext.Set<T>().Where(predicate);
        foreach (var includeProperty in includeProperties)
        {
            query = query.Include(includeProperty);
        }

        return query;
    }

    public virtual void Upsert(T entity, Func<T, bool> insertExpression)
    {
        if (insertExpression.Invoke(entity))
        {
            Add(entity);
        }
        else
        {
            Update(entity);
        }
    }

    public virtual void Add(T entity)
    {
        DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
        if (dbEntityEntry.State != EntityState.Detached)
        {
            dbEntityEntry.State = EntityState.Added;
        }
        else
        {
            DbSet.Add(entity);
        }
    }

    public virtual void Update(T entity)
    {
        DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
        if (dbEntityEntry.State == EntityState.Detached)
        {
            DbSet.Attach(entity);
        }
        dbEntityEntry.State = EntityState.Modified;
    }

    public virtual void Delete(T entity)
    {
        DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
        if (dbEntityEntry.State != EntityState.Deleted)
        {
            dbEntityEntry.State = EntityState.Deleted;
        }
        else
        {
            DbSet.Attach(entity);
            DbSet.Remove(entity);
        }
    }

    public virtual void Delete(int id)
    {
        var entity = GetById(id);
        if (entity == null) return; // not found; assume already deleted.
        Delete(entity);
    }
}

输出正确显示所有房屋，但门类型数组为空。我错过了什么？

Answer 1

这是一对多关系。

这就是问题所在。关系修复不适用于多对多关系，仅适用于一对一或一对多关系。

执行查询后，需要手动构建导航属性。但在这种情况下你可以做到相对简单：

houses = dbquery
    .AsEnumerable()
    .Select(p => {
        p.house.DoorTypes = p.doorTypes;
        return p.house;
    });

同样的原因是为什么将导航集合显式加载到上下文中不适用于多对多关系，请参阅此问题：EF 4.1 loading filtered child collections not working for many-to-many及其答案，尤其是对Zeeshan Hirani解释的引用关于关于该主题的深层背景的关系修正。

Answer 2

当您从上下文获取所有房屋时，不清楚Uow.Houses.GetAll()如何实施，但尝试include DoorTypes成为结果：

return context.Houses.Include("DoorTypes");

并确保您使用现有ID传递idHousesTypeLis。

更新：Include是DbQuery的成员。将Set设置为IQueriable<T>时，它将变为不可用。所以，试试这个：

public class HouseRepository : EFRepository<House>
{
    public override IQueryable<House> GetAll()
    {
        return DbContext.Set<House>().Include("DoorTypes");
    }
}

条件包括不使用Entity Framework 5

2 个答案: