LINQ to see if all items in an object's List property are included in the current selection

Question

I have a Key object that has an attribute of type List<int> and it is called KeyProperties. Key object also has an int Id attribute.

class Key
{
   public int Id;
   public List<int> KeyProperties;
}

I have a list of integers called currentSelection.

I would like to prevent the user from creating a Key that has the exact same integers as in currentSelection. That means if currentSelection is:

List<int> = new List<int>() {7,8,10};

I do not want the user to create a Key with a KeyProperties attribute of (7,8,10). But still the user will be able to create Keys with (7,8) or (7,8,15).

How can I achieve this using LINQ?

Actually, `Key` is a *class*, and `Keyproperties` is a *property* (not an object and attribute). — Jonathan Wood, May 28 '15 at 15:19
a) Are the ints ensured in the Key ordered? b) Where and when do you want to do this _validation_? c) When the validation occurs how can the currentSelection is accessible? Is it a parameter or member variable or local variable? — g.pickardou, May 28 '15 at 15:20
@JonathanWood true, but I didn't want the reader to be confused when I say there is a property called `KeyProperties`. — disasterkid, May 28 '15 at 15:21
@Pedram meaning if an existing entry had `{7, 8, 9, 10}` then the user would not be able to add `{7, 8, 9}`? — D Stanley, May 28 '15 at 15:22
@DStanley `{7, 8, 9, 10}` is allowed. We just don't want to have an exact match and order is not important. — disasterkid, May 28 '15 at 15:24
@Pedram so your comment "both accepted" is wrong for `{10, 8, 7}` — Raphaël Althaus, May 28 '15 at 15:25
@RaphaëlAlthaus yes. sorry `{10, 8, 7}` should not be allowed. — disasterkid, May 28 '15 at 15:27
@RaphaëlAlthaus that is not going to happen in the program since the integers are primary key ids. — disasterkid, May 28 '15 at 15:42
So you may just do `list1.Except(list2).Any()` => if it's true, you can add the value. — Raphaël Althaus, May 28 '15 at 15:44

Binkan Salaryman · Answer 1 · 2015-05-28T15:32:14.700

1

//currentSelection.Sort();
//theKey.KeyProperties.Sort();
bool valid = !currentSelection.SequenceEqual(theKey.KeyProperties)

I recommend to switch to a ISet`1 implementation like HashSet`1 though to skip the sorting process if the order is irrelevant.

edited May 28 '15 at 15:32

answered May 28 '15 at 15:20

Binkan Salaryman

3,008
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This isn't a requirement? – Binkan Salaryman May 28 '15 at 15:21
Still works, just add in `.Sort()` to the selection and KeyProperties – Mourndark May 28 '15 at 15:22

score 1 · Answer 2 · answered May 28 '15 at 15:23

1

Use All:

List<int> currSelection = new List<int>() {7,8,10};

public bool CanCreateKey(List<int> keyToCheck)
{
   return !currSelection.All(i => keyToCheck.Contains(i));
}

answered May 28 '15 at 15:23

Amir Popovich

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This may be wrong if both `{7, 7, 8, 10}` and `{7, 8, 10}` are accepted – Raphaël Althaus May 28 '15 at 15:29
@RaphaëlAlthaus - I also will have problems if keyToCheck == null or if I'm out of memory :) – Amir Popovich May 28 '15 at 15:30
This is not the same problem. You just don't manage duplicates, if they are allowed, than you give wrong result. – Raphaël Althaus May 28 '15 at 15:30
@RaphaëlAlthaus - That's correct for the sequenceequals answers as well if they are allowed. – Amir Popovich May 28 '15 at 15:32
If duplicates are allowed -> SequenceEqual and my way is false. Otherwise -> my way is true and SequenceEqual is false. – Amir Popovich May 28 '15 at 15:36

Mourndark · Answer 3 · 2015-05-28T15:27:52.043

0

bool valid = !currentSelection.OrderBy(x => x).SequenceEqual(theKey.KeyProperties.OrderBy(x => x));

edited May 28 '15 at 15:27

answered May 28 '15 at 15:23

Mourndark

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Doesn't compile; either sort separatedly or use `OrderBy` – Dmitry Bychenko May 28 '15 at 15:25
Oops, getting my sorting methods mixed up! Thanks. – Mourndark May 28 '15 at 15:25

LINQ to see if all items in an object's List property are included in the current selection

3 Answers3