I have a Linq query, I want to return the RegistrationID (GUID) and an email. when the query gets to the foreach it jumps out on the value.
Can you tell me how the query should be wrote.
using( var fbdc = new FBDataContext() )
{
var query = ( from q in fbdc.Registrations
where q.BookingDateTime == DateTime.Now.AddDays( -1 )
select new
{
q.RegistrationID,
q.Email
} );
foreach( var value in query )
{
registrationId = value.RegistrationID;
email = value.Email;
}
}
Plus, I'm not sure if the query would work. Is there a way to test this?
The BookingDateTime is a DateTime so thought this would work as I only want the files from yesterday. Could I use a more exact expression to query the date(30/09/2014)?
You can use it by as below:
var query = ( from q in fbdc.Registrations
where q.BookingDateTime == DateTime.Now.AddDays( -1 )
select new
{
q.RegistrationID,
q.Email
} ).AsEnumerable();
Related
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?
I have the following linq query that is throwing an error if a budget doesn't have any categories. Am I doing something wrong? Can I just set sum to return 0 if there are no categories? I'm fairly new to linq to sql.
var r = from rec in DbContext.budgets
where rec.budgetID == updatedBudget.budgetID
select new
{
rec.budgetID,
rec.totalIncome,
totalSpent = rec.categories.Sum(a => a.amount)
};
return new JsonResult(r.FirstOrDefault(), JsonSettings);
you can try this.
var r = from rec in DbContext.budgets
where rec.budgetID == updatedBudget.budgetID
select new
{
rec.budgetID,
rec.totalIncome,
totalSpent = rec.categories != null ? rec.categories.Sum(a => a.amount) : 0
};
return new JsonResult(r.FirstOrDefault(), JsonSettings);
I have a linq query which joins a couple of tables and returns the value into an object. The query was working fine, till i added a where clause to in. Aftre the where clause, my query returns null.
Here's the code:
List<Int32> resourceSupervisorIdList = new List<Int32>();
resourceSupervisorIdList.Add(searchCriteriaTimesheet.ResourceId);
foreach (resource res in allSubordinateResources)
{
if (!resourceSupervisorIdList.Contains(res.id_resource))
resourceSupervisorIdList.Add(res.id_resource);
}
using (tapEntities te = new tapEntities())
{
var timesheetAll = (from tsh in te.timesheet_header
join rs in te.resources on tsh.id_resource equals rs.id_resource
join tsd in te.timesheet_detail on tsh.id_timesheet equals tsd.id_timesheet
where (resourceSupervisorIdList.Contains(rs.id_resource_supervisor))
select new TimesheetHeaderDetailsItem()
{
OrganizationId = rs.id_organization,
ProjectId = tsd.id_project,
StartDate = tsh.dte_period_start,
EndDate = tsh.dte_period_end,
ApprovedDate = tsh.dte_approved,
RejectedDate = tsh.dte_rejected,
SubmittedDate = tsh.dte_submitted,
});
if (timesheetAll == null || timesheetAll.Count() == 0)
{
return result;
}
}
Now, after adding the where clause, the code runs into the if condition. There are matching records in the table, but still i'm not able to get any records.
rs.id_resource_supervisor
is of type int in the mysql db.
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();
}
I am having trouble to return an IEnumerable and IList, I cant do it!
I am using EF 4 with POCOs
Here's the whole method:
//public IList<Genre> GetGenresByGame(int gameId)
public IEnumerable<Genre> GetGenresByGame(int gameId)
{
using(var ctx = new XContext())
{
var results =
from t0 in ctx.GameGenres
join t1 in ctx.GenreCultureDetails on t0.GenreId equals t1.GenreId
where t0.GameId == gameId && t1.CultureId == _cultureId
select new Genre
{
GenreId = t0.GenreId,
GenreName = t1.GenreName
};
return results.ToList();
}
}
I have tried different ways that I have found on the net.. but can't make it work!
Question 2:
I saw a screencast with Julie something, saying that "You should always return an ICollection" when using EF4.
Any thoughts about that ?
BR
EDIT:
When I load the page in Debug-mode i get these errors: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection. OR The entity or complex type 'XModel.Genre' cannot be constructed in a LINQ to Entities query.
Genre must not be a L2EF type. Try this:
public IEnumerable<Genre> GetGenresByGame(int gameId)
{
using(var ctx = new XContext())
{
var resultList =
from t0 in ctx.GameGenres
join t1 in ctx.GenreCultureDetails on t0.GenreId equals t1.GenreId
where t0.GameId == gameId && t1.CultureId == _cultureId
select new { t0.GenreId, t1.GenreName };
var genres = resultList.AsEnumerable().Select(o => new Genre
{
GenreId = o.GenreId,
GenreName = o.GenreName
});
return genres.ToList();
}
}
First an foremost if Genre is in the database you should select it? If you have FKs from Genre->GenreCultureDetails let me know and I can update the below, but from the looks of it you could do it like this:
using(var ctx = new XContext())
{
var results =
from g in ctx.Genre
join gcd in ctx.GenreCultureDetails on g.GenreId equals gcd.GenreId
where g.GameId == gameId && gcd.CultureId == _cultureId
select g;
return result.ToList();
}
Alternatively continue down your path select them into an annoynmous type, and then copy them. You can use select instead of convertall if you please.
IList<Genre> returnMe = Null;
using(var ctx = new XContext())
{
var results =
from t0 in ctx.GameGenres
join t1 in ctx.GenreCultureDetails on t0.GenreId equals t1.GenreId
where t0.GameId == gameId && t1.CultureId == _cultureId
select new
{
GenreId = t0.GenreId,
GenreName = t1.GenreName
};
returnMe = results.ToList().ConvertAll(x=>new Genre(){
GenreId = x.GenreId,
GenreName = x.GenreName
}
);
}
return returnMe;