/// <summary>
/// Loads a child collection in a more efficent way than the standard Include. Will run all involved queries as NoTracking
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="TChild"></typeparam>
/// <param name="query"></param>
/// <param name="context"></param>
/// <param name="collectionSelector">The navigation property. It can be filtered and sorted with the methods Where,OrderBy(Descending),ThenBy(Descending) </param>
/// <returns></returns>
public static EfuQueryable <T> IncludeEfu <T, TChild>(this IQueryable <T> query, DbContext context, Expression <Func <T, IEnumerable <TChild> > > collectionSelector)
where T : class
where TChild : class
{
var octx = (context as IObjectContextAdapter).ObjectContext;
var cSpaceTables = octx.MetadataWorkspace.GetItems <EntityType>(DataSpace.CSpace);
var cSpaceType = cSpaceTables.Single(t => t.Name == typeof(T).Name); //Use single to avoid any problems with multiple tables using the same type
var keys = cSpaceType.KeyProperties;
if (keys.Count > 1)
{
throw new InvalidOperationException("The include method only works on single key entities");
}
var fkGetter = GetForeignKeyGetter <T, TChild>(cSpaceTables);
PropertyInfo pkInfo = typeof(T).GetProperty(keys.First().Name);
var pkGetter = MakeGetterDelegate <T>(pkInfo);
var childCollectionModifiers = new List <MethodCallExpression>();
var childProp = SetCollectionModifiersAndGetChildProperty(collectionSelector, childCollectionModifiers);
var setter = MakeSetterDelegate <T>(childProp);
var e = new IncludeExecuter
{
ElementType = typeof(TChild),
SingleItemLoader = parent =>
{
if (parent == null)
{
return;
}
var children = octx.CreateObjectSet <TChild>();
GetRootEntityToChildCollectionSelector <T, TChild>(cSpaceType);
var q = ApplyChildCollectionModifiers(children, childCollectionModifiers);
var rootPk = pkGetter((T)parent);
var param = Expression.Parameter(typeof(TChild), "x");
var fk = GetFkProperty <T, TChild>(cSpaceTables);
var body = Expression.Equal(Expression.Property(param, fk), Expression.Constant(rootPk));
var where = Expression.Lambda <Func <TChild, bool> >(body, param);
q = q.AsNoTracking().Where(where);
setter((T)parent, q.ToList());
},
Loader = (rootFilters, parents) =>
{
var baseType = typeof(T).BaseType != typeof(object) ? typeof(T).BaseType : typeof(T);
var methodInfo = octx.GetType()
.GetMethod("CreateObjectSet", new Type[] { });
if (methodInfo == null)
{
return;
}
dynamic dynamicSet = methodInfo
.MakeGenericMethod(baseType)
.Invoke(octx, new Object[] { });
var set = dynamicSet.OfType <T>() as ObjectQuery <T>;
IQueryable <T> q = set;
foreach (var item in rootFilters)
{
var newSource = Expression.Constant(q);
var arguments = Enumerable.Repeat(newSource, 1).Concat(item.Arguments.Skip(1)).ToArray();
var newMethods = Expression.Call(item.Method, arguments);
q = q?.Provider.CreateQuery <T>(newMethods);
}
var lambdaExpression = GetRootEntityToChildCollectionSelector <T, TChild>(cSpaceType);
if (q == null)
{
return;
}
var childQ = q.SelectMany(lambdaExpression);
childQ = ApplyChildCollectionModifiers(childQ, childCollectionModifiers);
var dict = childQ.AsNoTracking().ToLookup(fkGetter);
var list = parents.Cast <T>().ToList();
foreach (var parent in list)
{
var prop = pkGetter(parent);
var childs = dict.Contains(prop) ? dict[prop].ToList() : new List <TChild>();
setter(parent, childs);
}
}
};
return(new EfuQueryable <T>(query.AsNoTracking()).Include(e));
}
public EfuQueryable <T> Include(IncludeExecuter include)
{
_includes.Add(include);
return(this);
}
