results = await query
.GroupJoin(_invitations.GetAll().AsNoTracking()
.Where(i => i.GroupId == groupId),
user => user.Id,
invitation => invitation.UserId,
(a, s) => new { User = a, Invitation = s})
.SelectMany(
ai => ai.Invitation.DefaultIfEmpty(),
(a, s) => new { Users = a.User, Invitations = s }
)
.Select(i => i.Users)
.Skip(skip)
.Take(take)
.ToListAsync();
Howdy. I have quite simple group join but I can't figure out how to sort invitations inside this group join. Problem is, I don't want to make simple orderBy(i => i.creationDate) but I want to do something like (but on queryable):
var list = new List<string> {"Fall","Mid","Spring"};
return _db.MiaLog1A.Where(m => m.Campus == selectedCampus)
.AsEnumerable()
.OrderBy(m => m.StudentName)
.ThenBy(m=> list.IndexOf(m.Term));
I need to order them by specific strings. Because I have a scenario where newest invitation isn't what I need. I want accepted invitation status first. Is there a way to do this?
I've tried things like that:
.OrderBy(i => sortOrderList.IndexOf(i.InvitationsStatus) in many places but it just throws.
Thank you in advance.
A pattern of
.OrderBy(m => m.StudentName)
.ThenBy(m => m.X == "y" ? 0 : (m.X == "x" ? 1:2))
Should translate if you want to sort by "y","x","z"
But I note that both examples you given; (fall, mid, spring) and (approved vs pending / not invited) are sorted in that order anyway.. you don't need to sort by the list index of these, you can just sort the strings ascending
Related
I have this entity structure:
Categories->Has many "Groups"->Has many "Types"->Has many "Items"
I need to get the descending tree (with includes) filtering by Item.Color == "blue", that is:
var tree = from c in db.Categories
.Include(ct =>
ct.Groups
.Select(gr =>
gr.Types
.Select(pr => pr.Products)
)
)
join g in db.Groups on c.CategoryId equals g.CategoryId
join t in db.Types on g.GroupId equals t.GroupId
join i in db.Items on t.TypeId equals i.TypeId
where i.Color == "blue" // example filter
select c;
With this query I have the descending tree, however I get Items with other colors.
I need only descending tree for blue items.
Thanks!
I am assuming you are using EntityFramework.
All you need to do is an include all the way down, and then use the .Any predicate on your entities. E.g.
var tree = db.Categories.Include(ct => ct.Groups.Select(gr =>
gr.Types.Select(pr =>
pr.Products)))
.Where(c => c.Groups.Any(g =>
g.Types.Any(t =>
t.Items.Any(i =>
i.Color == "blue"))))
.ToList()
A word of warning, if a type has multiple items, and only 1 is blue, you will get all of its Items, not just the blue one. But if a type has no blue items, you wont get it.
If you want to filter at each level, you will need to do projections at each level.
EDIT
So if you want to filter you have 2 options:
Projection at each level
Start by getting all blue items, and then retrieve theirs types, groups and categories.
Examples
1. Projections at each level
var tree = db.Categories.Include(ct => ct.Groups.Select(gr =>
gr.Types.Select(pr =>
pr.Products)))
.Where(c => c.Groups.Any(g =>
g.Types.Any(t =>
t.Items.Any(i =>
i.Color == "blue"))))
.Select(c => new { Groups = c.Groups.Where(g =>
g.Types.Any(t =>
t.Items.Any(i =>
i.Color == "blue"))
.Select( g => new { Types = g.Types.Where(t =>
t.Items.Any(i =>
i.Color == "blue"))
.Select(t => new { Items = t.Items.Where(i =>
i.Color == "blue")
.ToList() // Return list of anonymous types (
You cannot project back an entity type, you have to retrieve the annonymous types first, and then use Linq2Objects to project into the Entity type as EF will not allow you to do this. Often what I do is directly project into a view model ready for display.
I have the following code written to find common objects in a list of objects
https://dotnetfiddle.net/gCgNBf
..............................
var query = setOfPersons
.SelectMany(l => l.Select(l1 => l1))
.GroupBy(p => p.Id)
.Where(g => g.Count() == setOfPersons.Count);
After that, I need to convert "query" to a list of "Person" objects ( List ) to achieve something else.
I tried using "ToList()"... But it says:
" cannot convert IGrouping to a List ".
Can someone help me to fix it ?
Looking at your code it seems that what you are trying to achieve is to get the list of people that exist in each list. If so, you can use the following query:
var query = setOfPersons
.SelectMany(l => l.Select(l1 => l1))
.GroupBy(p => p.Id)
.Where(g => g.Count() == setOfPersons.Count)
.Select(x=>x.First()) // Select first person from the grouping - they all are identical
.ToList();
Console.WriteLine("These people appears in all set:");
foreach (var a in query)
{
Console.WriteLine("Id: {0} Name: {1}", a.Id, a.Name);
}
Here you select just a single item from each grouping, because they all are identical.
I'm working on a report right now that runs great with our on-premises DB (just refreshed from PROD). However, when I deploy the site to Azure, I get a SQL Timeout during its execution. If I point my development instance at the SQL Azure instance, I get a timeout as well.
Goal: To output a list of customers that have had an activity created during the search range, and when that customer is found, get some other information about that customer regarding policies, etc. I've removed some of the properties below for brevity (as best I can)...
UPDATE
After lots of trial and error, I can get the entire query to run fairly consistently within 1000MS so long as this block of code is not executed.
CurrentStatus = a.Activities
.Where(b => b.ActivityType.IsReportable)
.OrderByDescending(b => b.DueDateTime)
.Select(b => b.Status.Name)
.FirstOrDefault(),
With this code in place, things begin to go haywire. I think this Where clause is a big part of it: .Where(b => b.ActivityType.IsReportable). What is the best way to grab the status name?
EXISTING CODE
Any thoughts as to why SQL Azure would timeout whereas on-premises would turn this around in less than 100MS?
return db.Customers
.Where(a => a.Activities.Where(
b => b.CreatedDateTime >= search.BeginDateCreated
&& b.CreatedDateTime <= search.EndDateCreated).Count() > 0)
.Where(a => a.CustomerGroup.Any(d => d.GroupId== search.GroupId))
.Select(a => new CustomCustomerReport
{
CustomerId = a.Id,
Manager = a.Manager.Name,
Customer = a.FirstName + " " + a.LastName,
ContactSource= a.ContactSource!= null ? a.ContactSource.Name : "Unknown",
ContactDate = a.DateCreated,
NewSale = a.Sales
.Where(p => p.Employee.IsActive)
.OrderByDescending(p => p.DateCreated)
.Select(p => new PolicyViewModel
{
//MISC PROPERTIES
}).FirstOrDefault(),
ExistingSale = a.Sales
.Where(p => p.CancellationDate == null || p.CancellationDate <= myDate)
.Where(p => p.SaleDate < myDate)
.OrderByDescending(p => p.DateCreated)
.Select(p => new SalesViewModel
{
//MISC PROPERTIES
}).FirstOrDefault(),
CurrentStatus = a.Activities
.Where(b => b.ActivityType.IsReportable)
.OrderByDescending(b => b.DueDateTime)
.Select(b => b.Disposition.Name)
.FirstOrDefault(),
CustomerGroup = a.CustomerGroup
.Where(cd => cd.GroupId == search.GroupId)
.Select(cd => new GroupViewModel
{
//MISC PROPERTIES
}).FirstOrDefault()
}).ToList();
I cannot give you a definite answer but I would recommend approaching the problem by:
Run SQL profiler locally when this code is executed and see what SQL is generated and run. Look at the query execution plan for each query and look for table scans and other slow operations. Add indexes as needed.
Check your lambdas for things that cannot be easily translated into SQL. You might be pulling the contents of a table into memory and running lambdas on the results, which will be very slow. Change your lambdas or consider writing raw SQL.
Is the Azure database the same as your local database? If not, pull the data locally so your local system is indicative.
Remove sections (i.e. CustomerGroup then CurrentDisposition then ExistingSale then NewSale) and see if there is a significant performance improvement after removing the last section. Focus on the last removed section.
Looking at the line itself:
You use ".Count() > 0" on line 4. Use ".Any()" instead, since the former goes through every row in the database to get you an accurate count when you just want to know if at least one row satisfies the requirements.
Ensure fields referenced in where clauses have indexes, such as IsReportable.
Short answer: use memory.
Long answer:
Because of either bad maintenance plans or limited hardware, running this query in one big lump is what's causing it to fail on Azure. Even if that weren't the case, because of all the navigation properties you're using, this query would generate a staggering number of joins. The answer here is to break it down in smaller pieces that Azure can run. I'm going to try to rewrite your query into multiple smaller, easier to digest queries that use the memory of your .NET application. Please bear with me as I make (more or less) educated guesses about your business logic/db schema and rewrite the query accordingly. Sorry for using the query form of LINQ but I find things such as join and group by are more readable in that form.
var activityFilterCustomerIds = db.Activities
.Where(a =>
a.CreatedDateTime >= search.BeginDateCreated &&
a.CreatedDateTime <= search.EndDateCreated)
.Select(a => a.CustomerId)
.Distinct()
.ToList();
var groupFilterCustomerIds = db.CustomerGroup
.Where(g => g.GroupId = search.GroupId)
.Select(g => g.CustomerId)
.Distinct()
.ToList();
var customers = db.Customers
.AsNoTracking()
.Where(c =>
activityFilterCustomerIds.Contains(c.Id) &&
groupFilterCustomerIds.Contains(c.Id))
.ToList();
var customerIds = customers.Select(x => x.Id).ToList();
var newSales =
(from s in db.Sales
where customerIds.Contains(s.CustomerId)
&& s.Employee.IsActive
group s by s.CustomerId into grouped
select new
{
CustomerId = grouped.Key,
Sale = grouped
.OrderByDescending(x => x.DateCreated)
.Select(new PolicyViewModel
{
// properties
})
.FirstOrDefault()
}).ToList();
var existingSales =
(from s in db.Sales
where customerIds.Contains(s.CustomerId)
&& (s.CancellationDate == null || s.CancellationDate <= myDate)
&& s.SaleDate < myDate
group s by s.CustomerId into grouped
select new
{
CustomerId = grouped.Key,
Sale = grouped
.OrderByDescending(x => x.DateCreated)
.Select(new SalesViewModel
{
// properties
})
.FirstOrDefault()
}).ToList();
var currentStatuses =
(from a in db.Activities.AsNoTracking()
where customerIds.Contains(a.CustomerId)
&& a.ActivityType.IsReportable
group a by a.CustomerId into grouped
select new
{
CustomerId = grouped.Key,
Status = grouped
.OrderByDescending(x => x.DueDateTime)
.Select(x => x.Disposition.Name)
.FirstOrDefault()
}).ToList();
var customerGroups =
(from cg in db.CustomerGroups
where cg.GroupId == search.GroupId
group cg by cg.CustomerId into grouped
select new
{
CustomerId = grouped.Key,
Group = grouped
.Select(x =>
new GroupViewModel
{
// ...
})
.FirstOrDefault()
}).ToList();
return customers
.Select(c =>
new CustomCustomerReport
{
// ... simple props
// ...
// ...
NewSale = newSales
.Where(s => s.CustomerId == c.Id)
.Select(x => x.Sale)
.FirstOrDefault(),
ExistingSale = existingSales
.Where(s => s.CustomerId == c.Id)
.Select(x => x.Sale)
.FirstOrDefault(),
CurrentStatus = currentStatuses
.Where(s => s.CustomerId == c.Id)
.Select(x => x.Status)
.FirstOrDefault(),
CustomerGroup = customerGroups
.Where(s => s.CustomerId == c.Id)
.Select(x => x.Group)
.FirstOrDefault(),
})
.ToList();
Hard to suggest anything without seeing actual table definitions, espectially the indexes and foreign keys on Activities entity.
As far I understand Activity (CustomerId, ActivityTypeId, DueDateTime, DispositionId). If this is standard warehousing table (DateTime, ClientId, Activity), I'd suggest the following:
If number of Activities is reasonably small, then force the use of CONTAINS by
var activities = db.Activities.Where( x => x.IsReportable ).ToList();
...
.Where( b => activities.Contains(b.Activity) )
You can even help the optimiser by specifying that you want ActivityId.
Indexes on Activitiy entity should be up to date. For this particular query I suggest (CustomerId, ActivityId, DueDateTime DESC)
precache Disposition table, my crystal ball tells me that it's dictionary table.
For similar task to avoid constantly hitting Activity table I made another small table (CustomerId, LastActivity, LastVAlue) and updated it as the status changed.
I have three tables, car_type, car_manufacturer and car_model. When the user click on the particular vehicle type they want to browse, I'd like to show them a list of available manufacturers. The problem is the list of manufacturers is not distinct or unique. So if my db has three models from Mazda, Mazda will show up on the list 3 times. This is my controller:
public ActionResult Browse(string click_string)
{
var x = carDB.Models
.Include(b => b.Manufacturer)
.Include(a => a.VehicleType)
.Where(a => a.VehicleType.TypeName == click_string);
return View(x.ToList());
}
How can I write this to remove redundant listings? This is all new to me, so go easy on me.
You have to query for Manufacturers, not for Vehicles:
var x = carDB.Models.Where(a => a.VehicleType.TypeName == click_string)
.Select(a => a.Manufacturer)
.Distinct();
It usually works well to try and avoid Distinct altogether. You want manufacturers? Get manufacturers. And determine from there which ones you need: the ones that produce models that have click_string in their type name:
carDB.Manufacturers.Where(manufacturer => manufacturer.Models
.Any(model => model.VehicleType.TypeName == click_string))
You may want to include Models and/or VehicleType, that depends on what you want to show in the view.
First try doing a .Distinct() at the end of the query, if it does not work you might need to provide a custom comparer for the .Distinct()
You should be able to use .Distinct to return the distinct elements.
var x = carDB.Models
.Include(b => b.Manufacturer)
.Include(a => a.VehicleType)
.Where(a => a.VehicleType.TypeName == click_string)
.Distinct();
add distinct
var x = carDB.Models
.Include(b => b.Manufacturer)
.Include(a => a.VehicleType)
.Where(a => a.VehicleType.TypeName == click_string)
.Select(y => y)
.Distinct();
The .Select() might be a bit verbose but without trying it in my visual studio i put it in there for saftey
Is there any way in LINQ to do an OrderBy and then do a ThenBy with the ThenBy using the children of the parent object to do the secondary ordering?
_repository.GetActiveDepartmentGroupsWithDepartments().OrderBy(c => c.DepartmentGroupName).ThenBy(c => c.Departments.OrderBy(d => d.DepartmentName))
In the above case, c.Departments is an EntityCollection.
BTW: When I try the above and then do a ToList() on it, I get this error:
DbSortClause expressions must have a type that is order comparable.
Parameter name: key
Thanks in advance for any help or guidance.
It seems like you're trying to get a list of all departments ordered by group then department name. If so, then you probably want to do something like this:
var res = from c in _repository.GetActiveDepartmentGroupsWithDepartments()
from d in c.Departments
orderby c.DepartmentGroupName, d.DepartmentName
select d;
Or in method syntax:
var res = _repository.GetActiveDepartmentGroupsWithDepartments()
.SelectMany(c => c.Departments, (c,d) => new { c, d })
.OrderBy(x => x.c.DepartmentGroupName)
.ThenBy(x => x.d.DepartmentName)
.Select(x => x.d);
Since Deparment is a collection, you have to transform it to a scalar to use it for sorting.
One option is to select a single entity to in the collection, e.g. the name of the first department:
_repository.GetActiveDepartmentGroupsWithDepartments()
.OrderBy(c => c.DepartmentGroupName)
.ThenBy(c => c.Departments
.OrderBy(d => d.DepartmentName)
.FirstOrDefault()
.DepartmentName
)
Another option is to order by a property of the collection itself, e.g. the number of departments:
_repository.GetActiveDepartmentGroupsWithDepartments()
.OrderBy(c => c.DepartmentGroupName)
.ThenBy(c => c.Departments.Count())