I am trying to use distinct() in my dropdownlistFor in order to get rid of duplicates.
Model.Categories contains a list of strings.
Been trying different "combinations" but cant get it to work..I thought the below example would do the tric but it still shows duplicates.
#Html.DropDownListFor(model => model.CatDropTemp,
Model.Categories.Select(kat => new SelectListItem { Text = kat, Value = kat }).Distinct())
Do I maybe have to change the whole construction of the list or is there something im missing?
EDIT:
Found this syntax here at the forum:
#Html.DropDownList(
"Foo",
new SelectList(
Model.Categories.Select(x => new { Value = x, Text = x }).Distinct(),
"Value",
"Text"
)
)
That takes care of the Distinct()-part, however...With this syntax I cant see where I add my
new{#class="form-control"}
Any tips on that maybe?
I think you need to do your distinct earlier in the chain, it doesn't look like SelectListItem implements any Equality/Comparison interfaces (assuming your model overrides Equals and GetHashCode)
Related
I am using jqgrid in MVC 4. I have written a method for getting a list in linq.
In my function I am getting all values of jqgrid with search criteria i.e. Operator AND/OR
, operations Equals to, not equals to etc. Here I am also getting the column name like Name, City, State etc.
My problem is I can't pass the column name directly in linq query i.e. I have to use the column name as x => x.Name
switch (rule.field)
{
case "Name":
query = query.Where(x => x.Name.StartsWith(rule.data, StringComparison.OrdinalIgnoreCase));
break;
case "Course":
query = query.Where(x => x.Course.StartsWith(rule.data, StringComparison.OrdinalIgnoreCase));
break;
}
In rule.field I am getting column Name i.e. Name, city, state etc. I want to pass the column name which I am getting in rule.filed in LINQ query instead of x =>x.Name.
Is there any way to do it so I can avoid writing switch cases?
You can use System.Linq.Dynamic, which can be installed as a Nuget package along with string.Format. The syntax would then look something like..
var newquery = query.AsQueryable()
.Where(
string.Format("{0}.ToUpper().StartsWith(#0)", rule.field)
,rule.data.ToUpper());
You could always use reflection:
query = query.ToList().Where(p => {
var field = p.GetType().GetProperty(rule.field);
var value = (String) field.GetValue(p);
return value.StartsWith(rule.data, StringComparison.OrdinalIgnoreCase);
});
Warning: Reflection is slow. Only use this for short lists. Since you're dealing with UI rendering, I'm assuming this won't be a problem.
edit: My example is assuming all properties are indeed properties (and not fields), and that all properties are Strings. You may need to alter the code for your specific case.
I'm trying Sort on IList, I have tried different approach but none works
here is what my code looks like:
IList<IWebElement> listCountIdsUi = driver.FindElements(By.CssSelector("table#ct_ tr td:nth-of-type(1)"));
List<Int32> ui = new List<Int32>();
foreach (IWebElement option in listCountIdsUi)
{
if (!option.Text.ToString().StartsWith("Page"))
{
ui.Add(Convert.ToInt32(option.Text));
}
}
the only way I able to figured out is working with ArrayList
ArrayList al = new ArrayList(ui);
al.Sort();
is not possible using IList ?
OrderBy does NOT modify the underlying collection - it returns an IEnumerable that gives you the items in the order you ask for. So you have a few options:
Use List.Sort(), which does modify the underlying collection:
ui.Sort();
Store the sorted list in a new variable
var uiSorted = ui.OrderBy(s => s);
replace the existing reference
ui = ui.OrderBy(s => s).ToList();
Have you tried the List<T>.Sort method?
ui.Sort((a, b) => a.CompareTo(b));
var uiOrdered = ui.OrderBy(s => s).ToList() should be all you need to do.
So I have this list, it returns an ID and a thumbnail. ex. List<PersonPicture>
and I have this list, List<Person> which has a property named "picture" in it.
Is there anyway that I can merge this two properties and add the List<PersonPicture> to the property named "picture" in it and base this via the ID since they have the same?
Any help would be appreciated.
You can use an anonymous object for this, below an example:
List<PersonPicture> pictures = LoadPictures();
List<Person> persons = LoadPersons();
var result = persons.Select(pers => new
{
Id = pers.Id,
Name = pers.Name,
Picture = pictures.Where(pic => pic.PersId == pers.Id)
.FirstOrDefault()
.Thumbnail
};
Another solution is to use a Join:
var result = persons.Join(pictures,
pers => pers.Id,
pic => pic.PersId,
(pers, pic) => {
return new
{
Id = pers.Id,
Name = pers.Name,
Picture = pic.Thumbnail
};
});
LINQ isn't quite designed for modifying existing collections like this, but you can do it:
foreach (tup in people
.Join(
picture,
person => person.ID,
picture => picture.ID,
Tuple.Create
))
{
tup.Item1.Picture = tup.Item2;
}
EDIT: Note that this will produce unpredictable results if a person has more than one picture. Is this a possibility, and how should it be dealt with?
You could either use a Join or the Zip operator in linq. These links will take you to questions about the syntax of using both of them. Basically the Join just adds the two lists together based on a key just like in SQL and the Zip merges the two lists by matching the position of each element in each list..
You want to join the two lists based on a shared key -- the ID.
Basically, you want to use the Join operator in LINQ to find pairs of Person and PersonPicture that match the same ID:
persons.Join(pictures, // join these two lists
person => person.Id, // extract key from person
personPicture => personPicture.PersonId, // extract key from picture
(person, personPicture) => ??? // do something with each matching pair
The question you now face is what to do with each matching pair; Join lets you supply a delegate that takes a matching pair and returns something else, and the result of the Join operation will be a list of those 'something else's produced from each of the matching pairs.
Your problem is that you want to take each pair and do something with it -- specifically, you want to copy the picture from the PersonPicture object to the Person object. Since LINQ is all about finding data but not modifying it, this is not trivial.
You can do this in two ways. One is to create a temporary object from each pair, and then iterate over that and do your thing:
var pairs = persons.Join(pictures,
person => person.Id,
personPicture => personPicture.PersonId,
(person, personPicture) => new { person, personPicture };
foreach (var pair in pairs)
pair.person.Picture = pair.personPicture.Thumbnail;
(You can use a Tuple instead of a temporary object, as was suggested in another answer).
This works, but seems clumsy because of the temporary object (be it an anonymous object or a tuple).
Alternatively, you can do the assignment right inside the delegate, and return the Person object itself, since you're done with the PersonPicture object:
var personsWithPicturesPopulated = persons.Join(pictures,
person => person.Id,
personPicture => personPicture.PersonId,
(person, personPicture) => {
person.Picture = personPicture.Thumbnail;
return person;
});
This has the added bonus of giving you the list of persons for which you found a match in the personPictures list, omitting the ones without a match; this is sometimes exactly what you need (and other times it isn't, in which case you can discard the result of the join).
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));
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Is it possible to Pivot data using LINQ?
I'm wondering if its at all possible to create crosstab style results with Linq.
I have some data that looks like the following:
var list = new[]
{
new {GroupId = 1, Country = "UK", Value = 10},
new {GroupId = 1, Country = "FR", Value = 12},
new {GroupId = 1, Country = "US", Value = 18},
new {GroupId = 2, Country = "UK", Value = 54},
new {GroupId = 2, Country = "FR", Value = 55},
new {GroupId = 2, Country = "UK", Value = 56}
};
and I'm trying to output to a repeater control something like the following:
GroupId.....UK.....FR.....US
1...........10.....12.....18
2...........54.....55.....56
Its the dynamic columns that are causing my problems. Any solutions to this?
You need a runtimy class to hold these runtimy results. How about xml?
XElement result = new XElement("result",
list.GroupBy(i => i.GroupId)
.Select(g =>
new XElement("Group", new XAttribute("GroupID", g.Key),
g.Select(i => new XAttribute(i.Country, i.Value))
)
)
);
Are you expecting multiple records per result cell? If so there would need to be some Summing (and more grouping) in there.
(this answer is proof of concept, not final result. There's several issues to address, such as: ordering of columns, missing cells, and so on).
After doing a quick search you might want to look at the ModuleBuilder, TypeBuilder, and FieldBuilder classes in System.Reflection.Emit. They allow you to create a class dynamically at runtime. Outside of that you would need to do grouping on your objects and then do something with the hierarchical results you get from LINQ. I am not sure of a way to dynamically create anonymous type fields at runtime, and that sounds like what would need to happen.
You could try using the dynamic linq library provided by MS. They have a number of overloads to extensions methods that take strings as arguments. They also have an expression parser that takes a string an emits a lambda expression. You should be able to create a dynamic select using them.
A word of warning though, you end up with a non-generic IQueryable rather than a generic IQueryable so you are a little bit limited on what you can do with the result, and you give up a bit of type safety, but that may be OK in your application...
The link for the dynamic linq stuff is
http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx
There is a link where you can download the source code the the dynamic library, plus some nice illustrations of how you can use it.
var labResults = from lab in CoreLabResults
where lab.Patient == 8
group lab by new { lab.Patient, lab.TestNo, lab.CollectedDate }
into labtests
select new
{
labtests.Key.Patient,
labtests.Key.TestNo,
labtests.Key.CollectedDate,
MCHC = labtests.Where(lab => lab.TestVar == "MCHC").FirstOrDefault().Result,
LYABS = labtests.Where(lab => lab.TestVar == "LYABS").FirstOrDefault().Result,
TotalTests = labtests.Count()
}