Hello I'm trying to copy the following linq results to a datatable. The only examples I see of copytodatatable is using the query format, and not the extension methods. Wondering if anyone knows how to use it with the extension methods (I've tried casting the results to IEnumerable datarow but it didn't work).
DataTable dtItemPricingBreakDown =
SiteHelper.getItemPricingBreakDown(CustomerId,
PriceBookID,
deliveryZip,
dtItems,
db,
departmentId);
dtItemPricingBreakDown.AsEnumerable()
.GroupBy(i => new {
sku = i.Field<string>("sku"),
deptid = i.Field<int>("department_id")
})
.Select(group => new
{
sku = group.Key.sku,
deptid = group.Key.deptid,
cnt = group.Count()
});
Update
Better late than never, sorry for the delay in response. My actual issue appears to be for both the query syntax and the extension methods.
Something like this works according to msdn
(http://msdn.microsoft.com/en-us/library/bb386921(v=vs.110).aspx):
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable orders = ds.Tables["SalesOrderHeader"];
DataTable details = ds.Tables["SalesOrderDetail"];
var query =
from order in orders.AsEnumerable()
join detail in details.AsEnumerable() on order.Field<int>("SalesOrderID") equals detail.Field<int>("SalesOrderID")
where order.Field<bool>("OnlineOrderFlag") == true
&& order.Field<DateTime>("OrderDate").Month == 8
select new
{
SalesOrderID = order.Field<int>("SalesOrderID"),
SalesOrderDetailID = detail.Field<int>("SalesOrderDetailID"),
OrderDate = order.Field<DateTime>("OrderDate"),
ProductID = detail.Field<int>("ProductID")
};
DataTable orderTable = query.CopyToDataTable();
But when I try this...
var query = from exx in dtItemPricingBreakDown.AsEnumerable()
group exx by new { sku = exx.Field<string>("sku"), companyId = exx.Field<int>("department_id") } into grp
select new { sku = grp.Key.sku, DepartmentID = grp.Key.companyId, Cnt = grp.Count() };
DataTable dt3 = query.CopyToDataTable();
I get this exception: "No implicit reference conversion from anonymoustype1 to system.data.datarow". I've tried doing what they did with the dataset in the msdn example as well and I still get the error. Extension method wise I was trying something like this...and still got the same exception.
DataTable dt3 = dtItemPricingBreakDown.AsEnumerable().GroupBy(i => new
{
sku = i.Field<string>("sku"),
deptid = i.Field<int>("department_id")
}).Select(group => new
{
sku = group.Key.sku,
DepartmentID = group.Key.deptid,
cnt = group.Count()
}).Cast<DataRow>().CopyToDataTable();
Related
I'm converting from EF6 to EF Core 3.1 and this LINQ query is failing with a runtime exception stating 'The LINQ expression ... could not be translated.
The group by is what is causing the issue, but I'm not sure how to rewrite it to work with EF Core and keep the result in a nested list.
Notification notification = new Notification()
{
ProductReminders = new List<List<ProductNotification>>(),
ProductStats = new List<StatResult>()
};
var profileCode = 123;
notification.ProductReminders =
(from ng in ProductNotification
where ng.UserProfileCode == profileCode
orderby ng.EndDate ?? DateTime.MaxValue
group ng by ng.GroupGUID into groupG
select (from pn in ProductNotification
join p in Product on pn.ProductID equals p.ProductID
where pn.UserProfileCode == profileCode
&& pn.GroupGUID == groupG.Key
orderby pn.EndDate ?? DateTime.MaxValue
select new ProductNotification()
{
ProductDetail = new ProductDetail()
{
ProductId = pn.ProductID ?? 0,
Upc = p.UPC,
Brand = p.Description,
Manufacturer = p.Name,
ProfileCode = p.ProfileCode,
},
EndDate = pn.EndDate,
NotificationId = pn.NotificationID,
Status = pn.Status,
GroupGuid = pn.GroupGUID
})
.ToList())
.ToList();
Since grouping operator has limitations, I would suggest to read all needed data and provide grouping on the client side. Query in your case will be much effective:
// select only needed data from database
var minimalRequiredData =
from pn in ProductNotification
join p in Product on pn.ProductID equals p.ProductID
where pn.UserProfileCode == profileCode
select new ProductNotification
{
ProductDetail = new ProductDetail
{
ProductId = pn.ProductID ?? 0,
Upc = p.UPC,
Brand = p.Description,
Manufacturer = p.Name,
ProfileCode = p.ProfileCode,
},
EndDate = pn.EndDate,
NotificationId = pn.NotificationID,
Status = pn.Status,
GroupGuid = pn.GroupGUID
};
// materialize result
var materialized = minimalRequiredData.ToList();
// form required result shape using IEnumerable<T>
var resultQuery =
from m in materialized
orderby ng.EndDate ?? DateTime.MaxValue
group m by new m.GroupGUID into g
select g.Orderby(x => x.EndDate ?? ng.EndDate).ToList();
notification.ProductReminders = resultQuery.ToList();
I want to add a dummy member to an IQueryable and came up with this solution:
IQueryable<Geography> geographies = _unitOfWork.GeographyRepository.GetAll(); //DbSet<Geography>
var dummyGeographies = new Geography[] { new Geography { Id = -1, Name = "All" } }.AsQueryable();
var combinedGeographies = geographies.Union(dummyGeographies);
var test = combinedGeographies.ToList(); //throws runtime exc
But it throws the following exception:
Processing of the LINQ expression 'DbSet
.Union(EnumerableQuery { Geography, })' by 'NavigationExpandingExpressionVisitor' failed. This may indicate either a bug or a limitation in EF Core.
How could I make it work?!
you can only union on data structure which are the same
IQueryable is only applicable if the query expression not been been expressed (ToList) before its run against db and you want the expression modifiable . aka nothing which which is not going to db as a query needs to be IQueryable (simple explanation better to research and understand this yourself)
List<Geography> geographies = _unitOfWork.GeographyRepository
.GetAll() //DbSet<Geography>
.Select(o => new Geography { Id = o.Id, Name = o.Name })
.ToList();
List<Geography> dummyGeographies = new List<Geography>() {
new Geography[] { new Geography { Id = -1, Name = "All" } }
};
var combinedGeographies = geographies.Union(dummyGeographies);
var test = combinedGeographies.ToList();
I was able to achieve it with the following code:
IQueryable<Geography> geographies = _unitOfWork.GeographyRepository.GetAll().Select(o => new Geography { Id = o.Id, Name = o.Name });
IQueryable<Geography> dummyGeographies = _unitOfWork.GeographyRepository.GetAll().Select(o => new Geography { Id = -1, Name = "All" });
var combinedGeographies = geographies.Union(dummyGeographies);
How would I go about changing my if statement and foreach to something cleaner in linq using select and where.
I've tried to make the if statement into a where clause and then use the select query as a replacement for the Foreach loop but that seem to have type issues and wasn't working.
{
StripeConfiguration.ApiKey = _appSettings.StripeSecretKey;
var profile = await _userManager.FindByIdAsync(customerServiceID);
var stripeId = profile.StripeAccountId;
if (stripeId == null)
throw new ArgumentException("No associated Stripe account found.");
List<PaymentMethodDto> result = new List<PaymentMethodDto>();
var options = new PaymentMethodListOptions
{
Customer = stripeId,
Type = "card",
};
var service = new PaymentMethodService();
var payments = await service.ListAsync(options);
if (payments != null && payments.Data?.Count > 0)
{
payments.Data.ForEach((x) =>
{
result.Add(
new PaymentMethodDto
{
Brand = x.Card.Brand,
LastDigits = x.Card.Last4,
StripeToken = x.Id,
CustomerID = x.CustomerId
});
});
}
return result;
}
Just do a regular Select.
List<PaymentMethodDto> result = payments.Data.Select(x => new PaymentMethodDto
{
Brand = x.Card.Brand,
LastDigits = x.Card.Last4,
StripeToken = x.Id,
CustomerID = x.CustomerId
})
.ToList();
If payments.Data has nothing in it, this will give you an empty list, which is what you want.
If payments is null, you'll get an exception, which I think if you think about it really hard is probably what you really want in that case too. Why would .ListAsync() yield a null value?
Hi im too new on entity framework and im using it on windows form app.
using (GezentiEntities GE = new GezentiEntities())
{
var cities = from c in GE.Cities
where c.CountryId == ((Guid)(dgCountry.SelectedRows[0].Cells[0].Value))
select new { c.Id, Şehir = c.Name };
dgCity.DataSource = cities.ToList();
}
on dgCity.DataSource = cities.ToList(); line it gives me error when im using it with where condition and ((Guid)(dgCountry.SelectedRows[0].Cells[0].Value)) that code works fine it gives me ID.
you may try to get the needed ID out of the linq to entities query
var id = (Guid)dgCountry.SelectedRows[0].Cells[0].Value;
var cities = from c in GE.Cities
where c.CountryId == id
select new { c.Id, Şehir = c.Name };
dgCity.DataSource = cities.ToList();
I am trying to get a record from database using linq but it keep return no record
it is very basic sql statment
select * where productid ='12553'
however the following code does not return any result. Please advise. thx you
private static IEnumerable<ProductModel> GetAllProduct(string productId)
{
using (var dc = new TestEntities())
{
var result = (from a in dc.Products
where a.productid == productId
select new ProductModel
{
ProductId = a.productid,
Name = a.ProductName
});
return result.Distinct().ToList();
}
}
You don't need projection here:
using (var dc = new TestEntities())
{
var result = from a in dc.Products
where a.productid == productId
select a;
return result.Distinct().ToList();
}