Except issues with List Object

Question

I have two lists: List totalkeys = GridView.GetCurrentPageRowValues(StudentId CourseId); List selectedkeys = GridView.GetSelectedFieldValues(StudentId CourseId); I have two lists one with the total keys and the other list with selected keys. I want to have a third list with unselected keys. So I am trying to use this piece of code without any success. List unselectedkeys = totalkeys.Except(selectedkeys); Am I missing anything? Any other suggestions ? Thanks

Vulpes · Answer

OK let's try this: List totalkeys = GridView.GetCurrentPageRowValues(StudentId CourseId); List selectedkeys = GridView.GetSelectedFieldValues(StudentId CourseId); string[] totalStrings = new string[totalkeys.Count]; for (int i = 0; i { object[] temp = (object[])totalkeys[i]; string row = temp[0].ToString() +  :  + temp[1].ToString(); totalStrings[i] = row; } string[] selectedStrings = new string[selectedkeys.Count]; for (int i = 0; i { object[] temp = (object[])selectedkeys[i]; string row = temp[0].ToString() +  :  + temp[1].ToString(); selectedStrings[i] = row; } IEnumerable unselected = totalStrings.Except(selectedStrings);

Mahesh Chand · Answer

DesiGal Please do not use in the title of a post. We found a bug on the forums. Thanks!

Desi Gal · Answer

Awesome...That works.... Thank you so much

Desi Gal · Answer

string row = totalkeys[0][0].ToString() + totalkeys[0][1].ToString();//gives me compile time error cannot apply indexing to an expression of type object but i can extract the values using foreach (object key in totalkeys ) { int StudentId= Convert.ToInt32(((object[])(key))[0]); int CourseId= Convert.ToInt32(((object[])(key))[1]); }

Vulpes · Answer

I'm not familiar with the Devexpress grid but that suggests to me that an object array is returned for each row containing the values for StudentId and CourseId. Just experimenting here but if you do this do you get anything sensible in the 'row' variable ? string row = totalkeys[0][0].ToString() + totalkeys[0][1].ToString();

Desi Gal · Answer

Yes I'm using Devexpress grids. I don't care about the form I'm just trying to get all the unselected values. string test= totalkeys [0].ToString(); The return value for the above line is System.Object[]

Vulpes · Answer

As I didn't recognize the methods you've posted I did a search on google and I gather it's the Devexpress gridview you're using so it's really a specialist question. Are you trying to get the values of the unselected rows in string form or in the form of whatever sort of object is in the List ? To get an idea of the format what does totalkeys[0].ToString() and selectedkeys[0].ToString() return?

Desi Gal · Answer

List selectedkeys = keys.Except(selectedkeyValues) as List ; //returns null var unselected = keys.Except(selectedkeyValues);//returns all the keys

Vulpes · Answer

You are using the Except extension method correctly. If it's not giving the right answer then the only thing I can think of is that the selectedKeys are clones of their counterparts in the keys collection and the default equality comparer is therefore saying that they're unequal because they're not the same objects. Does the 'except' method in fact return all the keys?