I am having trouble converting this linq query to a lambda expression, I tried to solve it using include but not successful, please help
(from PS in _dbNavigation.Table1
join CP in _dbNavigation.Table2 on PS.PropName equals CP.PropName
where PS.IsDeleted == false && PS.UserName.Equals("REX")
select CP).ToList();
_dbNavigation.Table1
.Join(_dbNavigation.Table2, t1 => t1.PropName, t2 => t2.PropName, (t1, t2) => new { t1, t2 })
.Where(x => x.t1.IsDeleted == false && x.t2.UserName == "REX")
.Select(x => x.t2);
Related
I got this linq query which searches for selected values in my database using dropdowns.
Is there a way to hide the "join" in the linq query if the ddlCategory is null? I want this because the result of the search shows duplicated-rows because my documents can have many Categories.?? hope you understand what i mean.. Can anyone help??
var documents = from d in data.tblDocuments
join sc in data.tblSubCategories on d.DocId equals sc.DocId
orderby d.Docyear descending
where
(string.IsNullOrEmpty(person) || d.DocPerson.Equals(person)) &&
(string.IsNullOrEmpty(year) || d.Docyear.Equals(year)) &&
(string.IsNullOrEmpty(law) || d.DocLaw.Equals(law)) &&
(string.IsNullOrEmpty(court) || d.DocCourt.Equals(court)) &&
(string.IsNullOrEmpty(category) || sc.CategoryId.Equals(category)) &&
(string.IsNullOrEmpty(casenr) || d.DocNr.Equals(casenr))
select d;
Use lambda syntax:
var query = data.tblDocuments;
if (condition) // conditionally add join
query = query.Join(data.tblSubCategories.Where(sc => sc.CategoryId == category),
d => d.DocId, sc => sc.DocId, (d,sc) => d);
// continue to compose query
query = query.OrderByDescending(d => d.Docyear)
.Where(d => ...);
BTW you can compose filtering based on conditions:
if (!String.IsNullOrEmpty(person))
query = query.Where(d => d.DocPerson == person);
I'm trying to get a row count for reports that a user has that match a particular channelId. I've tried using lambda expressions without any luck.
int count =
_reportsRepository.
GetMany(r => r.UserId == user.Id &&
(r.Charts.Any(cr => cr.Channels.Any(ch => ch.Id == channel.Id))).Any()).Count();
What about
int count = _reportsRepository.Where(
r => r.UserId == user.Id &&
r.User.Channels.Any(c => c.Id == channel.Id)).Count();
What is the equivalent lambda syntax to this linq query?
Dim query = From t In _rdsqlconn.Tags Where t.TagWord = tag
Join p In _rdsqlconn.Posts On t.PostId Equals p.PostId Order By p.PostDatePublished
Descending Select p Where p.PostIsPublished = True
You can do this with a join, like so:
_rdsqlconn.Tags
.Where(t => t.TagWord == tag)
.Join(_rdsqlconn.Posts, t => t.PostId, p => p.PostId, (t, p) => p)
.Where(p => p.PostIsPublished == true)
.OrderByDescending(p => p.PostDatePublished)
but what you want to do is properly map your tables and relationships in the LINQ-to-SQL designer, and then you can use
_rdsqlconn.Posts.Where(p => p.PostIsPublished && p.Tags.Any(t => t.TagWord == tag))
.OrderByDescending(p => p.PostDatePublished)
If you have a foreign key between Posts and Tags in your database then you will be able to do this. It's much cleaner code, and removes the unnecessarily Join operator.
I use LINQ, C#, EF4.
I have this query expression in Linq. I need to convert in a equivalent in Method Syntax but I have some doubt on the struction. Could you provide me a good example. Thanks for your help.
var myContentsForAuthor = from c in context.CmsContents
join a in context.CmsAuthors on c.AuthorId equals a.AuthorId
join u in context.aspnet_Users on a.UserId equals u.UserId
orderby c.Title ascending
where u.UserId == myUserGuid && c.IsDeleted == false && c.Title.Contains(nameSearchString)
select c;
Well, this gets complicated because of the transparent identifiers, but something like:
var myContentsForAuthor = context.CmsContents
.Join(context.CmsAuthors,
c => c.AuthorId
a => a.AuthorId,
(c, a) => new { c, a })
.Join(context.aspnet_Users,
z => z.a.UserId,
u => u.UserId,
(z, u) => new { z, u })
.OrderBy(zz => zz.z.c.Title)
.Where(zz => zz.u.UserId == myUserGuid &&
zz.z.c.IsDeleted == false &&
zz.z.c.Title.Contains(nameSearch))
.Select(zz => zz.z.c);
I was receiving repeating rows from this linq query:
public static Func<DataContext, string, IQueryable<Building>>
GearFilteredBuildings =
CompiledQuery.Compile((DataContext db, string filter) =>
from b in db.Building
join r in db.Router on b equals r.Building
orderby !b.Active
where filter.Length == 5 && r.Name.Substring(1, 5).ToLower() == filter
|| filter.Substring(0, 3) == r.Name.Substring(3, 3).ToLower()
select b);
After some fiddling, I got the distinct Buildings with this:
public static Func<DataContext, string, IQueryable<Building>>
GearFilteredBuildings =
CompiledQuery.Compile((DataContext db, string filter) =>
(from b in db.Building
join r in db.Router on b equals r.Building
orderby !b.Active
where filter.Length == 5 && r.Name.Substring(1, 5).ToLower() == filter
|| filter.Substring(0, 3) == r.Name.Substring(3, 3).ToLower()
group b by b.Id into g
select g) as IQueryable<Building>);
Is this an acceptable solution? How else might this be done?
Not sure (couldn't test it IDE) but select...join...lalala can replaced with Linq-Chain syntax:
db.Routers
.Where(r => filter.Length == 5 && r.Name.Substring(1, 5).ToLower() == filter || filter.Substring(0, 3) == r.Name.Substring(3, 3).ToLower())
.GroupBy(r => r.Building)
.Select(g => g.Key)
.OrderBy(b => !b.Active)
Also: as I can see no joins are really requred in your query, as you have navigation properties (r.Building)in your model.
Or another approach could be used, select all needed buildings, and use .Distinct() afterwards:
db.Routers
.Where (r => filter.Length == 5 && r.Name.Substring(1, 5).ToLower() == filter || filter.Substring(0, 3) == r.Name.Substring(3, 3).ToLower())
.Select(r => r.Building)
.Distinct()
.OrderBy(b => !b.Active)