I have these 3 tables/classes in the Entity Framework model:
Orders (OrderedItems, OrderTime)
OrderedItems (Product, Qty)
Products (Name, CreatedTime)
I can select the best-selling products by doing this
var items = Orders.SelectMany(o => o.OrderedItems);
var products = items.GroupBy(oi => oi.Product)
.OrderByDescending(g => g.Sum(oi => oi.Qty))
.Select(g => g.Key).Take(10);
How do I select the worst-performing products (ie. the opposite)?
Note: Worst-performing products may not exists in the Orders table because they may never be ordered.
You can start with the Products table and find matches from there. One way is to use the join into clause to group join the Products table with the OrderedItems:
var items = Orders.SelectMany(o => o.OrderedItems);
var products = (from product in Products
join item in items on product equals item.Product into matchingItems
orderby matchingItems.Sum(oi => oi.Qty)
select product).Take(10);
Another way, which is probably less efficient but you might find more readable, is to filter the items using Enumerable.Where():
var items = Orders.SelectMany(o => o.OrderedItems);
var products = (from product in Products
orderby items.Where(oi => oi.Product == product).Sum(oi => oi.Qty)
select product).Take(10);
This translates nicely into method syntax:
var items = Orders.SelectMany(o => o.OrderedItems);
var products = Products.OrderBy(p => items.Where(oi => oi.Product == product)
.Sum(oi => oi.Qty))
.Take(10);
var items = Orders.SelectMany(o => o.OrderedItems);
var products = items.GroupBy(oi => oi.Product)
.OrderBy(g => g.Sum(oi => oi.Qty))
.Select(g => g.Key).Take(10);
Try
OrderBy(g => g.Sum(oi => oi.Qty))
it will put minimum sums first.
Just change OrderByDescending to OrderBy and it should order them in ascending order.
It seems you need a left outer join from Products to OrderedItems. productsQty should contain a list of Products with Qty from OrderedItems or 0 if there was none.
var productQty = from p in Products
join oi in OrderedItems on p equals oi.Product into joined
from poi in joined.DefaultIfEmpty()
select new { Product = p, Qty = poi == null ? 0 : poi.Qty };
var products = productQty.GroupBy(p => p.Product).OrderBy(g => g.Sum(oi => oi.Qty)).Take(10);
UPDATE: Query corrected.
Related
What I am trying to do is get the top 10 most sold Vegetables by grouping them by an Id passed by parameter in a function and ordering them by the sum of their Quantity. I don't know how to use SUM or (total) quite yet but I thought I'd post it here seeking help. If you need me offering you anything else I will be ready.
This is my code:
TheVegLinQDataContext db = new TheVegLinQDataContext();
var query =db.OrderDetails.GroupBy(p => p.VegID)
.Select(g => g.OrderByDescending(p => p.Quantity)
.FirstOrDefault()).Take(10);
And this is an image of my database diagram
Group orders by Vegetable ID, then from each group select data you want and total quantity:
var query = db.OrderDetails
.GroupBy(od => od.VegID)
.Select(g => new {
VegID = g.Key,
Vegetable = g.First().Vegetable, // if you have navigation property
Total = g.Sum(od => od.Quantity)
})
.OrderByDescending(x => x.Total)
.Select(x => x.Vegetable) // remove if you want totals
.Take(10);
Since this is not clear that you are passing what type of id as function parameter, I'm assuming you are passing orderId as parameter.
First apply where conditions then group the result set after that order by Total sold Quantity then apply Take
LINQ query
var result = (from a in orderdetails
where a.OrderId == orderId //apply where condition as per your needs
group a by new { a.VegId } into group1
select new
{
group1.Key.VegId,
TotalQuantity = group1.Sum(x => x.Quantity),
group1.FirstOrDefault().Vegitable
}).OrderByDescending(a => a.TotalQuantity).Take(10);
Lamda (Method) Syntax
var result1 = orderdetails
//.Where(a => a.OrderId == 1) or just remove where if you don't need to filter
.GroupBy(x => x.VegId)
.Select(x => new
{
VegId = x.Key,
x.FirstOrDefault().Vegitable,
TotalQuantity = x.Sum(a => a.Quantity)
}).OrderByDescending(x => x.TotalQuantity).Take(10);
I am trying to do a join inside a groupjoin using Linq. Here's the scenario - for each lineitem in an order, I want to get some attributes from the variant for that line item(such as variant options and imageid which are stored in variant and product databases). i want to join lineitem, variant and product databases to get these extra information for the lineitem and then groupjoin this lineitem with the order table. i have done this and got the desired result using two queries but I am not sure how many database queries are run. And in the first case(ie in the join, a limit cannot be specified so I just want to make sure that the first iqueryable in the code below is evaluated only when .ToListAsync() is called). Is this the right way to do it? Any help would be greatly appreciated!
public async Task<dynamic> GetOrdersAsync(User user, int pageNumber = 1)
{
var perPage = 10;
var lineItemAndVariant = from l in _context.LineItems
join v in _context.Variants
on l.EcomPlatformVariantId equals v.EcomPlatformVariantId
join p in _context.Products
on v.ProductId equals p.Id
where p.UserId == user.Id
select new
{
l.Id,
l.OrderId,
l.Price,
l.Quantity,
l.EcomPlatformLineItemId,
l.EcomPlatformVariantId,
l.Title,
ImageId = v.ImageId ?? p.ThumbnailId, // for adding image
p.MyVendor,
p.MyVendorId,
v.Option1,
v.Option2,
v.Option3,
p.VariantOption1Label,
p.VariantOption2Label,
p.VariantOption3Label
};
var orders = await _context.Orders
.Where(o => o.UserId == user.Id)
.OrderByDescending(o => o.Id)
.Skip(perPage * (pageNumber - 1)).Take(perPage)
.GroupJoin(lineItemAndVariant, o => o.Id, l => l.OrderId,
(o, lineItems) => new
{
o.Id,
o.EcomPlatformOrderId,
o.CustomerEmail,
o.FirstName,
o.LastName,
o.Address1,
o.Address2,
o.City,
o.Company,
o.Country,
o.Currency,
o.OrderNumber,
o.Phone,
o.Province,
o.TotalPrice,
o.UserId,
o.Zip,
o.CreatedAt,
LineItems = lineItems
})
.AsNoTracking().ToListAsync();
return orders;
}
I have this simple code that returns a list of products but now I need to somehow fetch the same lis of products BUT i need to add a new column or value based on a view count.
var products = db.Products.Where(p => p.ProductOwnerUserId == userID).OrderByDescending(p => p.ProductID);
this is what i have so far but i am no expert in LINQ so i was wondering if someone could help me here.
This is a kind of pseudo-code of what i am looking for
var products = from p in db.Products
join pr in db.Reviews on p.ProductID equals pr.ReviewForProductID
into g select new
{
p.*,
ProductView = g.Count(a => a.ReviewForProductID)
};
i have found my OWN answer since nothing came up from you guys... but thanx for the initial tips... im quite new with linq and complexe queries can be hard to understand and fit inside existing code/view
here is my solution:
Thank you for your first answer and well just too bad for the second one that NEVER came... FYI, since my product class is a partial class already a just added another new ProductView.cs partial class containg the new Property and my query (functionnal and tested) looks like this now:
var products = (from p in db.Products
join pr in db.Reviews on p.ProductID equals pr.ReviewForProductID
into g
select new GenericEcomDataAccess.Product
{
ProductID = p.ProductID,
ProductOwnerUserId = p.ProductOwnerUserId,
ProductCurrency = p.ProductCurrency,
ProductDescription = p.ProductDescription,
ProductPrice = p.ProductPrice,
ProductImage = p.ProductImage,
ProductName = p.ProductName,
ProductCount = g.Count()
}).Where(p => p.ProductOwnerUserId == userID)
.OrderByDescending(p => p.ProductID).AsEnumerable();
var products = db.Products.Where(p => p.ProductOwnerUserId == userID)
.OrderByDescending(p => p.ProductID)
.Select(p=> new {Product = p, Count = p.Reviews.Count()});
If you have the foreign keys set up properly
I have two classes, Profile and Download. Download has the foreign key ProfileID which maps to the ID in Profile. Each row in Download represents one download for the connected profile.
I'm having trouble making a linq query that fetches a list of Profiles that is ordered in how many times it has been downloaded.
EDIT:
Here's what I have so far in the function.
IndexViewModel model = new IndexViewModel();
model.NewSubtitles = (from Profile in _ProfileRepo.GetAll()
orderby Profile.ID descending
select Profile).Take(5).ToList();
// This doesn't work:
// model.TopSubtitles = (from n in _ProfileRepo.GetAll()
// join d in _DownloadRepo.GetAll() on n.ID equals d.ProfileID into c
// group c by c.ProfileID into g
// orderby g.Count() descending
// select n).Take(5).ToList();
return View(model);
Try this :
model.NewSubtitles = (from Profile in _ProfileRepo.GetAll()
join downloads in _DownloadRepo.GetAll() on Profile.UserId equals downloads.UserId
group downloads by Profile into p
orderby p.Count() descending
select new {p.Key.UserId , p.Key.UserName , p.Count()).Take(5).ToList();
Have you tried something like :
from d in Downloads
orderby d.Profiles.Count()
...
?
Should do what you want:
model.TopSubtitles = (from p in _ProfileRepo.GetAll()
join d in _DownloadRepo.GetAll() on p.ID equals d.ProfileId
group d by p into g
orderby g.Count() descending
select g.Key).Take(5).ToList();
and for the LINQ syntax challenged:
model.TopSubtitles = _ProfileRepo.GetAll()
.Join(_DownloadRepo.GetAll(), p => p.ID, d => d.ProfileId, (p, d) => new { Profile = p, Download = d })
.GroupBy(x => x.Profile)
.OrderByDescending(g => g.Count())
.Select (g => g.Key)
.Take(5)
.ToList();
I didn't knew what title should I put, feel free to edit of course, English not my native language.
I have linked LINQ2SQL database that has Items and Categories in it. Items table has field IsActive.
How can I select all categories that has items in them who has IsActive set to true? I can select all items very easily var items = _db.Items.Where(x => x.IsActive == true); but can I somehow now select all categories that are associated with these items that I just selected?
My knowledge of LINQ is very limited so I have no idea how to do this.
Try something like as below
For each items active
var items = _db.Cateogry.Where(x => x.Items.All( y=>y.IsActive == true));
for any item active
var items = _db.Cateogry.Where(x => x.Items.Any( y=>y.IsActive == true));
Assuming each item has a CategoryID or similar, then:
from c in db.Categories
where db.Items.Any(it => it.CategoryID == c.ID && it.IsActive)
select c;
It's worth noting:
(from c in db.Categories join it in db.Items
on c.ID equals it.CategoryID
select c).Distinct();
Which is a bit needless in this case, but there are common variants upon this latter that gives you more than you can do with the former.
Assuming the appropriate association property is present, you can do:
var activeCategories = from category in _db.Categories
where category.Items.Any(item => item.IsActive)
select category;
If you must do a join, try something like:
var activeCategories = from category in _db.Categories
join item in _db.Items on category.Id equals item.CategoryId
into categoryGroup
where categoryGroup.Any(i => i.IsActive)
select category;
(or)
var activeCategories = from category in _db.Categories
join item in _db.Items.Where(i => i.IsActive)
on category.Id equals item.CategoryId
into categoryGroup
where categoryGroup.Any()
select category;
(or)
var activeCategories = from category in _db.Categories
where _db.Items
.Where(i => i.IsActive)
.Select(i => i.CategoryId)
.Contains(category.Id)
select category;