I want to conditionally exclude items from a query of tableA if an ID value for that query is NOT included at least once as a reference value in tableB... Something like this...
Initial query:
var jobs = from j in Jobs select j; // there's more, just keeping it simple...
I have tried these sub-queries...
Optional filtering based on a conditional:
jobs = jobs.Where(j => Bidders.Select(b => b.JobKey == j.JobKey) != null);
OR this:
jobs = jobs.Where(j => Bidders.Select(b => b.JobKey == j.JobKey).Count() > 0);
This does not seem to filter out jobs with no entries in the bidders table...
How should I do this???
If there is no navigation property already you were somewhat close with the first approach:
jobs = jobs.Where(j => Bidders.Any(b => b.JobKey == j.JobKey));
Related
I have a list of record that I picked up through the code:
var list= NhSession.QueryOver<Data.Models.MembModel>()
.Where(w => w.Comp.Id == idcomp)
.JoinQueryOver(jq => jq.Ver)
.Select(s => s.Ver)
.List<Dados.Models.VerModel>();
With this code I get a list of VerModel that I have relation in a MembModel. The problem is that I what get the list of VerModel that don't be in relation in a MembModal, I think to describe this, I want to select one list that is "notin" a first list. How can I do this?
Tks
What we need, as you said, is a NOT IN (subquery) statement. And NHibernate does have a clear way how to achieve that. First the subquery, which will return MembModel collection (filtered or not - as needed), represented by the VerModel.ID
var subquery = QueryOver.Of<Data.Models.MembModel>()
// we can still filter this sub-select ... or not
// .Where(w => w.Comp.Id == idcomp)
// what we need to be returned is the reference id, the VerModel.ID
.Select(m => m.Ver.ID);
And now we will query the VerModel itself, with the NOT IN (subquery) clause:
var list = session.QueryOver<Dados.Models.VerModel>()
.WithSubquery
.WhereProperty(v => v.ID) // the ID to match the prev selected one
.NotIn(subquery) // should NOT be IN
.List<Dados.Models.VerModel>();
Check:
16.8. Subqueries
I'm trying to filter a list within a list from an entity framework entity.
I've managed to get the code working however, i'm not convinced it's the cleanest way of achieving the goal.
Here's the code I have so far:
foreach (var n1 in tier.MatchNodes)
{
n1.LenderMatchNodes = n1.LenderMatchNodes.Where(x => x.Commission == 0).ToList();
}
Effectively MatchNodes contains a collection of LenderMatchNodes, however I want to return only the nodes where the commission == 0.
Thanks in advance.
Try
tier.MatchNodes.ToList().ForEach(n1=>n1.LenderMatchNodes = n1.LenderMatchNodes.Where(x => x.Commission == 0).ToList());
Try using SelectMany():
var result = dataContext.Table<Tier>()
.Where(some condition to get you the tier)
.SelectMany(tier => tier.MatchNodes)
.SelectMany(node => node.LenderMatchNodes)
.Where(x => x.Commission == 0)
.ToList();
This has the additional benefit of being able to execute it a single SQL query.
If you're goal is to actually update the node list in the database, you can still minimize the number of queries using Include() (assuming you're using EF):
var nodes = dataContext.Table<Tier>()
.Where(some condition to get you the tier)
.SelectMany(tier => tier.MatchNodes)
.Include(node => node.LenderMatchNodes) // loads this eagerly
.ToList();
nodes.ForEach(n => n.LenderMatchNodes = n.LenderMatchNodes.Where(condition));
I have the following linq-to-entities query with 2 joined tables that I would like to add pagination to:
IQueryable<ProductInventory> data = from inventory in objContext.ProductInventory
join variant in objContext.Variants
on inventory.VariantId equals variant.id
where inventory.ProductId == productId
where inventory.StoreId == storeId
orderby variant.SortOrder
select inventory;
I realize I need to use the .Join() extension method and then call .OrderBy().Skip().Take() to do this, I am just gettting tripped up on the syntax of Join() and can't seem to find any examples (either online or in books).
NOTE: The reason I am joining the tables is to do the sorting. If there is a better way to sort based on a value in a related table than join, please include it in your answer.
2 Possible Solutions
I guess this one is just a matter of readability, but both of these will work and are semantically identical.
1
IQueryable<ProductInventory> data = objContext.ProductInventory
.Where(y => y.ProductId == productId)
.Where(y => y.StoreId == storeId)
.Join(objContext.Variants,
pi => pi.VariantId,
v => v.id,
(pi, v) => new { Inventory = pi, Variant = v })
.OrderBy(y => y.Variant.SortOrder)
.Skip(skip)
.Take(take)
.Select(x => x.Inventory);
2
var query = from inventory in objContext.ProductInventory
where inventory.ProductId == productId
where inventory.StoreId == storeId
join variant in objContext.Variants
on inventory.VariantId equals variant.id
orderby variant.SortOrder
select inventory;
var paged = query.Skip(skip).Take(take);
Kudos to Khumesh and Pravin for helping with this. Thanks to the rest for contributing.
Define the join in your mapping, and then use it. You really don't get anything by using the Join method - instead, use the Include method. It's much nicer.
var data = objContext.ProductInventory.Include("Variant")
.Where(i => i.ProductId == productId && i.StoreId == storeId)
.OrderBy(j => j.Variant.SortOrder)
.Skip(x)
.Take(y);
Add following line to your query
var pagedQuery = data.Skip(PageIndex * PageSize).Take(PageSize);
The data variable is IQueryable, so you can put add skip & take method on it. And if you have relationship between Product & Variant, you donot really require to have join explicitly, you can refer the variant something like this
IQueryable<ProductInventory> data =
from inventory in objContext.ProductInventory
where inventory.ProductId == productId && inventory.StoreId == storeId
orderby inventory.variant.SortOrder
select new()
{
property1 = inventory.Variant.VariantId,
//rest of the properties go here
}
pagedQuery = data.Skip(PageIndex * PageSize).Take(PageSize);
My answer here based on the answer that is marked as true
but here I add a new best practice of the code above
var data= (from c in db.Categorie.AsQueryable().Join(db.CategoryMap,
cat=> cat.CategoryId, catmap => catmap.ChildCategoryId,
cat, catmap) => new { Category = cat, CategoryMap = catmap })
select (c => c.Category)
this is the best practice to use the Linq to entity because when you add AsQueryable() to your code; system will converts a generic System.Collections.Generic.IEnumerable to a generic System.Linq.IQueryable which is better for .Net engine to build this query at run time
thank you Mr. Khumesh Kumawat
You would simply use your Skip(itemsInPage * pageNo).Take(itemsInPage) to do paging.
I want a list of counts for some of my data (count the number of open.closed tasks etc), I want to get all counts inside 1 query, so I am not sure what I do with my linq statement below...
_user is an object that returns info about the current loggedon user
_repo is am object that returns an IQueryable of whichever table I want to select
var counters = (from task in _repo.All<InstructionTask>()
where task.AssignedToCompanyID == _user.CompanyID || task.CompanyID == _user.CompanyID
join instructions in _repo.GetAllMyInstructions(_user) on task.InstructionID equals
instructions.InstructionID
group new {task, instructions}
by new
{
task
}
into g
select new
{
TotalEveryone = g.Count(),
TotalMine = g.Count(),
TotalOpen = g.Count(x => x.task.IsOpen),
TotalClosed = g.Count(c => !c.task.IsOpen)
}).SingleOrDefault();
Do I convert my object to single or default? The exception I am getting is, this sequence contains more than one element
Note: I want overall stats, not for each task, but for all tasks - not sure how to get that?
You need to dump everything into a single group, and use a regular Single. I am not sure if LINQ-to-SQL would be able to translate it correctly, but it's definitely worth a try.
var counters = (from task in _repo.All<InstructionTask>()
where task.AssignedToCompanyID == _user.CompanyID || task.CompanyID == _user.CompanyID
join instructions in _repo.GetAllMyInstructions(_user) on task.InstructionID == instructions.InstructionID
group task by 1 /* <<=== All tasks go into one group */ into g select new {
TotalEveryone = task.Count(),
TotalMine = task.Count(), // <<=== You probably need a condition here
TotalOpen = task.Count(x => x.task.IsOpen),
TotalClosed = task.Count(c => !c.task.IsOpen)
}).Single();
From MSDN
Returns the only element of a sequence, or a default value if the
sequence is empty; this method throws an exception if there is more
than one element in the sequence.
You need to use FirstOrDefault. SingleOrDefault is designed for collections that contains exactly 1 element (or none).
I am a newbie to Linq. I am trying to write a linq query to get a min value from a set of records. I need to use groupby, where , select and min function in the same query but i am having issues when using group by clause. here is the query I wrote
var data =newTrips.groupby (x => x.TripPath.TripPathLink.Link.Road.Name)
.Where(x => x.TripPath.PathNumber == pathnum)
.Select(x => x.TripPath.TripPathLink.Link.Speed).Min();
I am not able to use group by and where together it keeps giving error .
My query should
Select all the values.
filter it through the where clause (pathnum).
Groupby the road Name
finally get the min value.
can some one tell me what i am doing wrong and how to achieve the desired result.
Thanks,
Pawan
It's a little tricky not knowing the relationships between the data, but I think (without trying it) that this should give you want you want -- the minimum speed per road by name. Note that it will result in a collection of anonymous objects with Name and Speed properties.
var data = newTrips.Where(x => x.TripPath.PathNumber == pathnum)
.Select(x => x.TripPath.TripPathLink.Link)
.GroupBy(x => x.Road.Name)
.Select(g => new { Name = g.Key, Speed = g.Min(l => l.Speed) } );
Since I think you want the Trip which has the minimum speed, rather than the speed, and I'm assuming a different data structure, I'll add to tvanfosson's answer:
var pathnum = 1;
var trips = from trip in newTrips
where trip.TripPath.PathNumber == pathnum
group trip by trip.TripPath.TripPathLink.Link.Road.Name into g
let minSpeed = g.Min(t => t.TripPath.TripPathLink.Link.Speed)
select new {
Name = g.Key,
Trip = g.Single(t => t.TripPath.TripPathLink.Link.Speed == minSpeed) };
foreach (var t in trips)
{
Console.WriteLine("Name = {0}, TripId = {1}", t.Name, t.Trip.TripId);
}