[英]EF Eager loading include multiple
我有這個存儲庫:
public class Repository<T> : IRepository<T> where T : class
{
private readonly DbContext context;
private readonly DbSet<T> dbEntitySet;
public Repository(DbContext context)
{
if (context == null)
throw new ArgumentNullException("context");
this.context = context;
this.dbEntitySet = context.Set<T>();
}
public IEnumerable<T> GetAll()
{
return this.dbEntitySet;
}
public IEnumerable<T> GetAll(string include)
{
return this.dbEntitySet.Include(include);
}
public IEnumerable<T> GetAll(string[] includes)
{
IQueryable<T> query = context.Set<T>();
foreach (var include in includes)
query.Include(include);
return query;
}
public void Create(T model)
{
this.dbEntitySet.Add(model);
}
public void Update(T model)
{
this.context.Entry<T>(model).State = EntityState.Modified;
}
public void Remove(T model)
{
this.context.Entry<T>(model).State = EntityState.Deleted;
}
public void Dispose()
{
this.context.Dispose();
}
}
我有一個服務,看起來像這樣:
public class Service<T> where T : class
{
private readonly IRepository<T> repository;
protected IRepository<T> Repository
{
get { return this.repository; }
}
internal Service(IUnitOfWork unitOfWork)
{
this.repository = unitOfWork.GetRepository<T>();
}
}
我的頁面服務看起來像這樣(簡化):
public class PageService : Service<Page>
{
// ...
public IList<Page> GetPublished()
{
return this.Repository.GetAll(new string[] { "ForbiddenUsers", "ForbiddenGroups" }).Where(model => model.Published).ToList();
}
// ...
}
為了清楚起見,我的頁面看起來像這樣:
public enum PageType
{
Root,
System,
Page,
Link,
Group
}
public partial class Page
{
public int Id { get; set; }
public System.DateTime DateCreated { get; set; }
public string CreatedById { get; set; }
public Nullable<System.DateTime> DateModified { get; set; }
public string ModifiedById { get; set; }
public string CompanyId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public string FileName { get; set; }
public string Path { get; set; }
public string ViewData { get; set; }
public string ViewTitle { get; set; }
public string Link { get; set; }
public bool Published { get; set; }
public PageType Type { get; set; }
public int Order { get; set; }
public string Lineage { get; set; }
public Nullable<int> ParentId { get; set; }
public bool Restricted { get; set; }
public bool Deleted { get; set; }
public Company Company { get; set; }
public User CreatedBy { get; set; }
public User ModifiedBy { get; set; }
public Page Parent { get; set; }
public MenuPage MenuPage { get; set; }
public ICollection<Page> Pages { get; set; }
public ICollection<User> ForbiddenUsers { get; set; }
public ICollection<Group> ForbiddenGroups { get; set; }
}
當我運行此代碼時, ForbiddenUsers和ForbiddenGroups始終為null。 如果我檢查調用堆棧,我可以看到生成的查詢如下所示:
SELECT
[Extent1].[Id] AS [Id],
[Extent1].[DateCreated] AS [DateCreated],
[Extent1].[CreatedById] AS [CreatedById],
[Extent1].[DateModified] AS [DateModified],
[Extent1].[ModifiedById] AS [ModifiedById],
[Extent1].[CompanyId] AS [CompanyId],
[Extent1].[Name] AS [Name],
[Extent1].[Description] AS [Description],
[Extent1].[FileName] AS [FileName],
[Extent1].[Path] AS [Path],
[Extent1].[ViewData] AS [ViewData],
[Extent1].[ViewTitle] AS [ViewTitle],
[Extent1].[Link] AS [Link],
[Extent1].[Published] AS [Published],
[Extent1].[Type] AS [Type],
[Extent1].[Order] AS [Order],
[Extent1].[Lineage] AS [Lineage],
[Extent1].[ParentId] AS [ParentId],
[Extent1].[Restricted] AS [Restricted],
[Extent1].[Deleted] AS [Deleted]
FROM [dbo].[Pages] AS [Extent1]
如你所見,這完全忽略了我的包含。
如果我將服務方法更改為:
public IList<Page> GetPublished()
{
return this.Repository.GetAll("ForbiddenUsers").Where(model => model.Published).ToList();
}
現在運行我的代碼, ForbiddenUsers現在已填充,調用堆棧顯示正確生成的查詢(太大而無法在此處粘貼)。
我需要允許多個包含但我無法弄清楚他們為什么不工作....
任何幫助將不勝感激....
您應該將包含的查詢分配回查詢變量,因為QueryableExtensions.Include創建新的DbQuery<T>
而不是修改現有的DbQuery<T>
。 另外我建議你使用params
來包含路徑:
public IEnumerable<T> GetAll(params string[] includes)
{
IQueryable<T> query = context.Set<T>();
foreach (var include in includes)
query = query.Include(include);
return query;
}
這將允許您傳遞所有包含的路徑,而無需顯式創建數組:
public IList<Page> GetPublished()
{
return Repository.GetAll("ForbiddenUsers", "ForbiddenGroups")
.Where(model => model.Published)
.ToList();
}
嘗試
foreach (var include in includes)
query = query.Include(include);
return query;
下面是C#6中的一個例子。 此外,請注意使用nameof運算符使代碼更易於維護,以便在重命名時不需要手動更新屬性名稱的字符串值。
// Assign the property names
var navigablePropertyNames = new[]
{
nameof(ParentEntity.Id),
nameof(ParentEntity.Name),
nameof(ParentEntity.Description)
};
// Do the inclusion
GetAll(navigablePropertyNames);
所以針對您的具體要求:
public IEnumerable<T> GetAll(params string[] inclusions)
{
var qry = this.dbEntitySet.AsQueryable();
foreach(var inclusion in inclusions)
{
qry = qry.Include(inclusion);
}
return qry;
}
用途:
// either
var resultSet1 = GetAll(nameof(ParentEntity.Id),
nameof(ParentEntity.Name),
nameof(ParentEntity.Description));
// or
var propertyNames = new[] {
nameof(ParentEntity.Id),
nameof(ParentEntity.Name),
nameof(ParentEntity.Description)};
var resultSet2 = GetAll(propertyNames);
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