[英]EF 5.0 - Loading collections of T
我想將下面的代碼寫得更加抽象。
private void LoadRelatedData(TabAccount tabAccount)
{
if (ConxCore.Instance.EntityModel.Entry(tabAccount).Collection(x => x.TabAccountLangs).IsLoaded == false)
{
var list = (from x in ConxCore.Instance.EntityModel.TabAccounts
from y in x.TabAccountLangs
select y).ToList();
}
}
我想抽象的部分如下:
.Entry(tabAccount) ->應該接受每個EntitySet
x => x.TabAccountLangs- >應該采用我在調用Method時指定的屬性(也許拋出MemberExpression)
從x ... TabAccounts- >應該從EntitySet加載DbSet我正在使用
從x.TabAccountLangs中的y- >應該是上面的屬性
關於抽象,我只是想避免一遍又一遍地復制/粘貼此代碼,而只是更改提到的4點,很高興能夠在給定參數的情況下調用此方法,而該方法完成了其余工作。
所以代替:
private void LoadRelatedData(TabAccount tabAccount)
{
if (ConxCore.Instance.EntityModel.Entry(tabAccount).Collection(x => x.TabAccountLangs).IsLoaded == false)
{
var list = (from x in ConxCore.Instance.EntityModel.TabAccounts
from y in x.TabAccountLangs
select y).ToList();
}
}
private void LoadRelatedData(TabElement tabElement)
{
if (ConxCore.Instance.EntityModel.Entry(tabElement).Collection(x => x.TabElementLangs).IsLoaded == false)
{
var list = (from x in ConxCore.Instance.EntityModel.TabElements
from y in x.TabElementLangs
select y).ToList();
}
}
像這樣(僅偽代碼):
private void LoadRelatedData(object obj, object collection, object dbSetOfObj)
{
if (ConxCore.Instance.EntityModel.Entry(obj).Collection(x => x.collection).IsLoaded == false)
{
var list = (from x in ConxCore.Instance.EntityModel.dbSetOfObj
from y in x.collection
select y).ToList();
}
}
並調用此方法:
LoadRelatedData(tabAccount, TabAccountLangs, TabAccounts);
LoadRelatedData(tabElement, TabElementLangs, TabElements);
希望你能幫助我。 提前致謝。
using System.Data.Entity; // For the Include extension method.
private void LoadRelatedData<TEntity, TRelated>(TEntity entity, Expression<Func<TEntity, ICollection<TRelated>> navigationProperty)
where TEntity : class
where TRelated : class
{
if (!ConxCore.Instance.EntityModel.Entry(entity).Collection(navigationProperty).IsLoaded)
{
var list = ConxCore.Instance.EntityModel.Set<TEntity>().Include(navigationProperty).ToList();
}
}
然后,您可以通過編寫以下內容來調用它:
LoadRelatedData(tabAccount, ta => ta.TabAccountLangs);
LoadRelatedData(tabElement, te => te.TabElementLangs);
但是,您知道這樣的調用將加載所有相關數據,對於任何x? 也就是說,您可能會以非特別優化的方式加載大量數據。 如果只想加載單個實體的相關數據,則可以從Collection
調用返回的對象中加載集合:
private void LoadRelatedDataOfSingleObject<TEntity, TRelated>(TEntity entity, Expression<Func<TEntity, ICollection<TRelated>> navigationProperty)
where TEntity : class
where TRelated : class
{
var collectionEntry = ConxCore.Instance.EntityModel.Entry(entity).Collection(navigationProperty);
if (!collectionEntry.IsLoaded) collectionEntry.Load();
}
但是,如果要加載許多對象的數據,則應考慮使用Include
擴展方法之一 。
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