How can I convert this linq query to single line?
var closets = (from v in options
select v.ExceriseDate).Min();
var option = options.Where(v => v.ExceriseDate == closets).Single();
return option;
Like so:
options.OrderBy(v => v.ExceriseDate).First();
I'll also add that you don't want to use Single() unless you can guarantee it will be unique. It will throw an exception if more than one exist. That would happen if two if your objects shared the same ExceriseDate. Lastly if you prefer the query syntax for Linq over the expression method:
var option = (from v in options
orderby v.ExceriseDate
select v).First();
I have to sort a collection based on sort-order field from another collection. I did it the following way.
var objresult = from err in ibusSoftErrors.iclbEmployerError
join codvalue in lclbCodeValue
on err.severity_id equals codvalue.icdoCodeValue.code_id
orderby codvalue.icdoCodeValue.code_value_order
select ibusSoftErrors.iclbEmployerError;
ibusSoftErrors.iclbEmployerError is the collection I would use in my grid. My problem is when I try to assign the query result to this collection am getting the following error.
Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<>' to 'System.Collections.ObjectModel.Collection<>'. An explicit conversion exists (are you missing a cast?)
Help me out to get the collection sorted using lambda or linq.
Binding usually requires an IList implementation so
var objresult = from err in ibusSoftErrors.iclbEmployerError
join codvalue in lclbCodeValue
on err.severity_id equals codvalue.icdoCodeValue.code_id
orderby codvalue.icdoCodeValue.code_value_order
select err;
var toBind = objresult.ToList();
grid.ItemsSource = toBind;
should do it (assuming a WPF/Silverlight datagrid)
I have a need to create a LINQ query that returns results based on a subquery. Not quite sure I'm wording that properly but the best way I know to ask is to show an example. How can I turn the following TSQL query into a LINQ query (tables are same name as objects):
SELECT CuisineId, Name
FROM Cuisine
WHERE CuisineId NOT IN (SELECT CuisineId
FROM RestaurantCuisine
WHERE RestaurantId = #id)
As you can guess, I'm trying to get a list of "available" cuisines to be listed for a user to add to a list of cuisines that a restaurant offers. The LINQ I have thus far returns ALL cuisines and doesn't take in account of the existing CuisineId's that have already been added to the other table:
I've looked all over for an example but not quite sure how to describe exactly what I need. I looked at the MSDN reference for LINQ queries but couldn't find anything like what I need:
MSDN LINQ Sample Queries
Anyone able to give me an example?
In C#:
var query =
from c in db.Cuisine
where !(from rc in db.RestaurantCuisine
where rc.RestaurantId == id
select rc.CuisineId)
.Contains(c.CuisineId)
select new {
c.CuisineId,
c.Name
};
In VB.NET:
Dim availableCuisines = _
From c In db.Cuisines _
Where Not (From rc In db.RestaurantCuisines _
Where rc.RestaurantId = id _
Select rc.CuisineId) _
.Contains(c.CuisineId) _
Select c
var cuisines = db.Cuisine.Where(c => !RestaurantCuisine.Any(
rc => rc.RestaurantId == c.Id && rc.CuisineId == c.CuisineId);
Try:
Cuisine.Where(c => !RestaurantCuisine.Select(rc => rc.CuisineID).Contains(c.CuisineID)).Select(c => c);
var query = (from c in Cuisine
where !(from rest in RestaurantCuisine
where (rest.RestaurantID == id)).Contains(c.CuisineId)
select new
{
CuisineID = c.CuisineID,
Name = c.Name
});
How I can use Like query in LINQ ....
in sql for eg..
name like='apple';
thanks..
Use normal .NET methods. For example:
var query = from person in people
where person.Name.StartsWith("apple") // equivalent to LIKE 'apple%'
select person;
(Or EndsWith, or Contains.) LINQ to SQL will translate these into the appropriate SQL.
This will work in dot notation as well - there's nothing magic about query expressions:
// Will find New York
var query = cities.Where(city => city.Name.EndsWith("York"));
You need to use StartsWith, Contains or EndsWith depending on where your string can appear. For example:
var query = from c in ctx.Customers
where c.City.StartsWith("Lo")
select c;
will find all cities that start with "Lo" (e.g. London).
var query = from c in ctx.Customers
where c.City.Contains("York")
select c;
will find all cities that contain "York" (e.g. New York, Yorktown)
Source
name.contains("apple");
I use item.Contains("criteria"), but, it works efficiently only if you convert to lower both, criteria and item like this:
string criteria = txtSearchItemCriteria.Text.ToLower();
IEnumerable<Item> result = items.Where(x => x.Name.ToLower().Contains(criteria));
I am trying to write a linq query that will only return certain columns from my entity object into a list object.
Below is my code which produces an error(can't implicitly convert a generic list of anonymous types to a generic list of type TBLPROMOTION):
IQueryable<TBLPROMOTION> matches = webStoreContext.TBLPROMOTION.Include("TBLSTORE").Include("LKPROMOTIONTYPE");
List<TBLPROMOTION> promotionInfo = null;
promotionInfo = (from p in matches
orderby p.PROMOTION_NM descending
select new { p.EFFECTIVE_DT, p.EXPIRE_DT, p.IS_ACTIVE,
p.PROMOTION_DESC, p.PROMOTION_ID, p.PROMOTION_NM }).ToList();
What would be the best way to accomplish this. I do not want to do a "select p" in this case and return all the columns associated with the query.
thanks in advance,
Billy
Can't you do var promotionInfo = () and get a list of anonymous types?
Okay, basically you can not cast an Anonymous type to a known type like TBLPROMOTION.
ofcourse, you can say var promotionInfo = and then get an IEnumerable<{Anonymoustype}> and use that to do, what you were wanting to do with promotionInfo.
Also, personally I prefer the Fluent version of a linq query, easy on the eyes, good programming diet, at least for me :)
var promotionInfo = matches
.OrderByDescending( p => p.PROMOTION_NM)
.Select( p => new { p.EFFECTIVE_DT,
p.EXPIRE_DT,
p.IS_ACTIVE,
p.PROMOTION_DESC,
p.PROMOTION_ID,
p.PROMOTION_NM})
.ToList();
If you're moving from a L2E query to a Type already defined, you may need a step between. I haven't tried to compile this but something like:
List<TBLPROMOTION> promotions = new List<TBLPROMOTION>();
var results = from p in matches
orderby p.PROMOTION_NM descending
select new
{
p.EFFECTIVE_DT,
p.EXPIRE_DT,
p.IS_ACTIVE,
p.PROMOTION_DESC,
p.PROMOTION_ID,
p.PROMOTION_NM
};
foreach (var v in results)
{
promotions.Add(new TBLPROMOTION(v.EFFECTIVE_DT, v.EXPIRE_DT, v.IS_ACTIVE,
v.PROMOTION_DESC, v.PROMOTION_ID, v.PROMOTION_NM));
}
Based on the comment below, you might try something like:
foreach(var v in results)
{
TBLPROMOTION temp = new TBLPROMOTION();
temp.EFFECTIVE_DT = v.EFFECTIVE_DT;
temp.EXPIRE_DT = v.EXPIRE_DT;
temp.IS_ACTIVE = v.IS_ACTIVE
// Assign Other Properties
promotions.Add(temp);
}
.......
Sorry: Just read the addition to the top.
Are you sure that none of the fields you're leaving out (instead of saying "select p") are required for a TBLPROMOTION object? Also, sense your TBLPROMOTION object is going to have properties (and therefore memory allocated) for those skipped fields, why not just use an annonymous type or set up a helper class that contains only your needed properties?
#Billy, following code worked for me.
List<TBLPROMOTION> promotionInfo =
(from p in matches
orderby p.PROMOTION_NM descending
select new TBLPROMOTION(p.EFFECTIVE_DT, p.EXPIRE_DT, p.IS_ACTIVE,
p.PROMOTION_DESC, p.PROMOTION_ID, p.PROMOTION_NM)
).ToList();
did you try
select new TBLPROMOTION {.....
instead of
select new {.....
List<TBLPROMOTION> promotionInfo = null;
promotionInfo = (from p in matches
orderby p.PROMOTION_NM descending
select new TBLPROMOTION { COL1 = p.EFFECTIVE_DT, COL2 = p.EXPIRE_DT, COL3 = p.IS_ACTIVE... }).ToList();
Where COL1, COL2, ... are the names of the properties on TBLPROMOTION you wish you populate.
If you want a subset of the table you have 2 options:
#Fredou mentioned select new TBLPROMOTION{...}
other way is to create a custom DTO which has the exact properties & select them instead like:
List promotionInfo = ...
select new TBLPROMOTION_DTO{
Effective_dt = ...
}
HTH