Intersect ef中的交集
我在调试的时候，看到2个list有共同的元素，为什么temp.Count() =0呢？
List<Department> temp = deptBranch.Intersect(deptList).ToList();
if (deptBranch.Intersect(deptList).ToList().Count() >= 2)
continue;
public static bool AddTask(Task task,int[] deptArr=null)
{
try
{
using (var db = new WEBVODEntities())
{
string loginName = CurrentProject.GetCurrentUser().LoginName;
//添加-Task-对象
task.TimeCreate = DateTime.Now;
task.ManCreate = loginName;
task.LoginName = loginName;
task.Guid = Guid.NewGuid().ToString();
db.Task.AddObject(task);
//添加-部门-任务
if (deptArr != null && (task.TypeId == Constants.TaskType_Global || task.TypeId == Constants.TaskType_Local))
{
List<Department> deptList = db.Department.Where(a => deptArr.Contains(a.Id)).OrderBy(a=>a.Level).ToList(); //级别高的排前边
//添加-TaskDept-对象
foreach (var dept in deptList)
{
//父节点已经被添加，就不再添加。
if (task.TypeId == Constants.TaskType_Global)
{
List<Department> deptBranch = DepartmentBLL.GetBranch(dept.Id); //!!!思考：每次都要数据库查询一次，有没有什么算法，可以只查询一次.
List<Department> temp = deptBranch.Intersect(deptList).ToList();
if (deptBranch.Intersect(deptList).ToList().Count() >= 2)
continue;
}
TaskDept taskDept = new TaskDept();
taskDept.Task = task;
taskDept.Department = dept;
taskDept.TimeCreate = DateTime.Now;
//db.TaskDept.AddObject(taskDept);
}
}
//添加-个人-任务
if(task.TypeId == Constants.TaskType_Per)
{
TaskDept taskDept = new TaskDept();
taskDept.Task = task;
taskDept.LoginName = loginName;
taskDept.TimeCreate = DateTime.Now;
//db.TaskDept.AddObject(taskDept);
}
db.SaveChanges();
}
}
catch
{
}
return false;
}
Person publicPerson = new Person() { Id = 1, Name = "a", Count = 1 };
List<Person> list1 = new List<Person>() {
new Person(){Id=1,Name="a",Count=1},
new Person(){Id=2,Name="a",Count=1},
new Person(){Id=3,Name="a",Count=1}
};
List<Person> list2 = new List<Person>() {
new Person(){Id=1,Name="a",Count=1}
};
int count1 = list1.Intersect(list2).Count();//0
List<Person> list3 = new List<Person>() {
publicPerson,
new Person(){Id=2,Name="a",Count=1},
new Person(){Id=3,Name="a",Count=1}
};
List<Person> list4 = new List<Person>() {
publicPerson
};
int count2 = list3.Intersect(list4).Count();//1
Product[] store1 = { new Product { Name = "apple", Code = 9 },
new Product { Name = "orange", Code = 4 } };
Product[] store2 = { new Product { Name = "apple", Code = 9 },
new Product { Name = "lemon", Code = 12 } };
...
// Get the products from the first array
// that have duplicates in the second array.
IEnumerable<Product> duplicates =
store1.Intersect(store2, new ProductComparer());
foreach (var product in duplicates)
Console.WriteLine(product.Name + " " + product.Code);
/*
This code produces the following output:
apple 9
*/public class Product
{
public string Name { get; set; }
public int Code { get; set; }
}
// Custom comparer for the Product class
class ProductComparer : IEqualityComparer<Product>
{
// Products are equal if their names and product numbers are equal.
public bool Equals(Product x, Product y)
{
//Check whether the compared objects reference the same data.
if (Object.ReferenceEquals(x, y)) return true;
//Check whether any of the compared objects is null.
if (Object.ReferenceEquals(x, null)
[解决办法]
Object.ReferenceEquals(y, null))
return false;
//Check whether the products' properties are equal.
return x.Code == y.Code && x.Name == y.Name;
}
// If Equals() returns true for a pair of objects
// then GetHashCode() must return the same value for these objects.
public int GetHashCode(Product product)
{
//Check whether the object is null
if (Object.ReferenceEquals(product, null)) return 0;
//Get hash code for the Name field if it is not null.
int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();
//Get hash code for the Code field.
int hashProductCode = product.Code.GetHashCode();
//Calculate the hash code for the product.
return hashProductName ^ hashProductCode;
}
}