I do a linq to sql query to get a list:
var list1 = db.Table1.Where(a => a.item == "Widgets").ToList();
Now I want to get a list from another table using the results of list above:
var list2 = db.Table2.Where(a => list1.Contains(a.GUID)).ToList();
So far this all works as expected.
Now I want to do a query where I find all rows in another DB table that have GUIDs from my list2
var list3 = db.MyTable.Where(a => list2.Contains(a.GUID)).ToList();
The data types are all the same in the three tables so I know those match. But I get the best overloaded match has some invalid arguments?
You are missing the Where-clause in your third line:
var list3 = db.MyTable.Where(a => list2.Contains(a.GUID)).ToList();
EDIT: Okay, this was only a type and the question was edited, see new answer below.
Looking at your exception
System.Collections.Generic.List.Contains(Test1.Data.Models.Table1)' has some invalid arguments
We can see that list2 is of type List<Test1.Data.Models.Table1>, yet you try to run list2.Contains(long). You have to change
var list2 = db.Table2.Where(a => list1.Contains(a.GUID)).ToList();
to
var list2 = db.Table2.Where(a => list1.Contains(a.GUID)).Select(a => a.GUID).ToList();
Then list2 should be of type List.
I am personally not a big of var because you cannot extract the exact type of a variable from source code. If you change your vars to "real" data types you may see your problem far easier.
Related
I have two queries. I want to assign the list values returned from these two queries to a single list, send it to the view and meet it in the view. My goal is to learn to work with lists in C#.
var list1 = c.ETs.Where(p => p.prop != "yes").ToList();
var list2 = c.ETs.Where(p => p.prop == "yes").ToList();
You can merge two lists into one with this:
var newList = List1
.Concat(List2)
.ToList();
Though you could drop the ToList and work directly with the IEnumerable which means you don't need to create a new object.
However, this doesn't even need to be two queries since the Where clauses of both are opposite so they include the entire table, you could do:
var list = c.ETs.ToList();
Or if you want to have two different clauses that aren't simply opposites:
var list = ct.ETs
.Where(p => p.prop == "yes" || p.prop == "no")
.ToList()` for example
This will combine the values of both lists in a single list (the final output will be stored in List1):
List1.AddRange(List2);
Hi Ahmet you can try something like this but note you will need Linq:
var list3 = List1.Concat(List2).ToList();
or if you have more than 2 lists:
var list3 = list1.Concat(list2)
.Concat(list3)
.ToList();
Another method:
var list3 = List1.AddRange(List2);
Both above will create a new list containing both lists' items.
I have a list of strings like this
"Users": [
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
"usrName|Fullname|False|0|False|False",
]
In my episerver/optimizely code I want to match items. I have written this line of code
searchResult.Filter(x => x.Users.MatchContained(k=> k.Split('|')[3], "0"));
I am trying to get all Users where after splitiing on 'pipe' I get 0 at index 3. I am not getting the result, infact I get an exception.
What am I doing wrong here?
Since you left out A LOT of details these are my assumptions
Users is an IList<string> Users
You are trying to get all Users within that list/array where index 3 equals 0
What we don't know is, among others
Is there more than one page instance that have the Users instance filled?
Anyway, this cannot be solved using any Find API with the current system design. Instead you need to rely on linq to parse the result, but then the Find implementation may not be necessary.
var searchClient = SearchClient.Instance;
var search = searchClient.Search<BlogPage>();
var result = search.GetContentResult();
var usersResult = result
.SelectMany(x => x.Users)
.Where(x => x.Split('|')[3].Equals("0"));
This would create and return an object similar to this, since I'm using SelectMany the array would contain all users throughout the systems where there are matched pages from the search result.
If you for whatever reason would like to keep or see some page properties there are alternative approaches where you construct a new object within a select and remove any object where there where not matched users
var searchClient = SearchClient.Instance;
var search = searchClient.Search<BlogPage>();
var result = search.GetContentResult();
var usersResult = result
.Select(p => new
{
PageName = p.Name,
ContentLink = p.ContentLink.ToString(),
Users = p.Users.Where(x => x.Split('|')[3].Equals("0"))
})
.Where(x => x.Users.Any());
If you like to keep using Find for this kind of implementations you must store the data in a better way than strings with delimiters.
I'm sure I must be missing something really simple here..
OK I have a list of AreaIds. I want to compare that list to the MapArea Table and return any IDs that exist in the table but NOT in the supplied list.
This is my list of supplied areas that I want to check:
var currentAreas = (from c in _entities.mapAreaLink
where c.listingId == id
select new
{
c.MapArea.areaId
}
).ToList();
This is the getting the exhaustive list of mapAreas..
var availableAreas = (from m in _entities.MapAreas
select new
{
m.areaId
}
).ToList();
This compares the two lists and gets items that exist in the maparea table but not in the maparealink (constrained by an id of the item I am looking at).
var unusedAreas = availableAreas.Except(currentAreas).ToList();
I seem to get the list back ok, but what I need to do is now return a list of maparea objects based on the results of the Except.tolist above.
I thought I could do this:
var mapareas = (from e in _entities.MapAreas
where unusedAreas.Contains(e.areaId)
select e).ToList();
I am getting an ambiguous invocation on the where & "Cannot resolve method Contains(int)" on the e.areaId.
Ive tried using:
var unusedAreas = availableAreas.Except(currentAreas).ToArray();
No Joy.. Can anyone help me out here - I am guessing I must be missing a fundamental basic here.
many thanks
You create anonymous types with just one int property. That's not necessary and it causes the later problem. If you create lists of int you'll be OK:
var currentAreas = (from c in _entities.mapAreaLink
where c.listingId == id
select c.MapArea.areaId).ToList();
var availableAreas = (from m in _entities.MapAreas
select m.areaId).ToList();
I want to do something like DELETE FROM TABLE WHERE ID NOT IN (1,2,3) AND PAGEID = 9
I have a List of IDS but that could be changed if needs be. I can't work out how to get a boolean result for the LINQ parser.
Here is what Subsonic expects I think.
db.Delete(content => content.PageID == ID).Execute();
I can't work out how to do the NOT IN statement. I've tried the List.Contains method but something not quite right.
UPDATE: One alternative is to do:
var items = TABLE.Find(x => x.PageID == ID)'
foreach(var item in items)
{
item.Delete();
}
This hits the database a lot more though
When you say "something not quite right" what exactly do you mean?
I'd expect to write:
List<int> excluded = new List<int> { 1, 2, 3 };
db.Delete(content => !excluded.Contains(content.PageID)).Execute();
Note that you need to call Contains on the array of excluded values, not on your candidate. In other words, instead of saying "item not in collection" you're saying "collection doesn't contain item."
Try .Contains:
db.Delete(content => content.PageID.Contains(<Array containing ID's>).Execute();
(the above is just an example, might need some polishing for your specific situation)
I have found that this works but its not via LINQ
var table = new WebPageContentTable(_db.DataProvider);
var g = new SubSonic.Query.Delete<WebPageContent(_db.DataProvider)
.From(table)
.Where(table.ID)
.NotIn(usedID)
.Execute();
I have found that this does work and via LINQ - however it hits the database multiple times.
var f = WebPageContent.Find(x => !usedID.Any(e => e == x.ID));
if (f.Count > 0)
{
var repo = WebPageContent.GetRepo();
repo.Delete(f);
}
This I imagine would work in one hit to the database but I get an exception thrown in QueryVisitor::VisitUnary
WebPageContent.Delete(x => !usedID.Any(e => e == x.ID));
I'm trying to retrieve a list of Id's from a collection that is a few levels deep in an object heirachy. When i try to do a ToList(), I keep getting an EntityList<> retrieved instead .. which means it's not allowing me to retrieve an instance's BarId property because the EntitySet is a Enumerable, not a single instance object.
Foo.Child1 (1 to 1)
Child1.Children2 (0 to many of type Bar)
Bar.BarId int;
IList<Foo> fooList = (from blah blah blah).ToList();
var children2List = (from x in fooList
select x.Child1.Children2).ToList();
It keeps returning children2List as an EntitySet<Bar>, not an IList<Bar>. As such, i'm struggling to retrieve the list of BarId's from children2List.
please help!
Your can use:
var children2List = fooList.SelectMany( x => x.Child1.Children2 ).ToList();
This will allow you to do something like:
children2List.ForEach( b => b.BarId.Print() );
In your query, you turn the whole result into a list, not the individual Children2 sets.
Try
var children2List = (from x in fooList
select x.Child1.Children2.ToList()).ToList();
This will turn each Children2 into a List.
EntitySet<T> implements IList<T>, so you already are returning IList<Bar>.