I have the code below, run it in LinqPad 4.40.03 + Sql Server 2008 R2 + NorthWind.
LinqPad return exception: "ArgumentNullException: Value cannot be null. Parameter name: httpContext".
Please give me the Final Fixed code, I want it populate a chart ( Using System.Web.Helpers.Chart ) in linqpad output screen.
void Main()
{
var q = from p in Products
let s = p.OrderDetails.Sum(o => o.Quantity) * p.UnitPrice
orderby s
select new { ProductName = p.ProductName, Sales = s};
var basicChart = new System.Web.Helpers.Chart(width: 600, height: 400)
.AddTitle("Product Sales")
.DataBindTable(dataSource: q, xField: "ProductName")
.Write();
basicChart.Dump();
}
The ASP.NET charting control relies on HttpContext.Current which is present only when running an ASP.NET application.
You could try mocking an HttpContext, or else use the charting control in System.Windows.Forms.DataVisualization.Charting instead:
var q = from p in Products
let s = p.OrderDetails.Sum(o => o.Quantity) * p.UnitPrice
orderby s
select new { ProductName = p.ProductName, Sales = s};
var chart = new Chart();
var ca = new ChartArea();
ca.AxisX.LabelStyle.Interval = 1;
chart.ChartAreas.Add (ca);
var series = new Series { ChartType = SeriesChartType.Bar};
series.Points.DataBind (q.Take(20), "ProductName", "Sales", null);
chart.Series.Add (series);
chart.Dump ("Chart");
Related
[HttpGet]
public JsonResult GetData()
{``
ApplicationDbContext db = new ApplicationDbContext();
var course = db.Courses
.Include(d=>d.Competences)
.Include(d=>d.Sequences)
.ToList().Select(p => new { Id = p.Id, Titre = p.Titre, ShortDescription = p.ShortDescription, Price = p.Price, CategorieId = p.CategorieId });
var query = from q in db.Courses
join cat in db.Categories.AsEnumerable()
on q.CategorieId equals cat.Libelle
enter code here
return Json(new { data = course },
JsonRequestBehavior.AllowGet);
}
I've currently got the SQL code below:
WITH region_list
AS (SELECT r.StateProvinceRegion,
r.CafeId,
s.Longitude,
s.Latitude,
ROW_NUMBER() OVER(PARTITION BY r.StateProvinceRegion
ORDER BY s.Longitude DESC) AS row_no
FROM CafeAddress r
inner join Restaurant s on s.CafeId = r.CafeId
)
SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS ID,
StateProvinceRegion,
Longitude,
Latitude
FROM region_list
WHERE row_no = 1;
How would I go about adding this query? In my method below I've implemented something similar but I don't understand how to add the WITH clause in.
public VersionResponse GetCafeRegion()
{
var regionList = from cafeAddress in _context.CafeAddress
join cafe in _context.Cafe on cafeAddress.CafeId equals cafe.CafeId
select new { cafeAddress.StateProvinceRegion, cafeAddress.CafeId, cafe.Longitude, cafe.Latitude };
return new VersionResponse()
{
Data = regionList
};
}
Try the below code once.
public VersionResponse GetCafeRegion()
{
var CafeAddress = new List<CafeAddress>();
var Cafe = new List<Cafe>();
var regionList = from cafeAddress in _context.CafeAddress
join cafe in _context.Cafe on cafeAddress.CafeId equals cafe.CafeId
group new { cafeAddress.StateProvinceRegion, cafeAddress.CafeId, cafe.Longitude, cafe.Latitude } by cafeAddress.StateProvinceRegion into g
select g;
List<object> finalResult = new List<object>();
int index = 1;
foreach(var gg in regionList)
{
var groupRecord = gg.OrderByDescending(x => x.Longitude).FirstOrDefault();
finalResult.Add(new
{
ID = index++,
groupRecord.StateProvinceRegion,
groupRecord.CafeId,
groupRecord.Latitude,
groupRecord.Longitude
});
}
return new VersionResponse()
{
Data = finalResult
};
}
I want to get count of a set based on different condition:
var invoices = new AccountingEntities().Transactions
var c1 = invoices.Count(i=>i.Type = 0);
var c2 = invoices.Count(i=>i.Type = 1);
var c3 = invoices.Count(i=>i.Type = 2);
How its possible to call all three queries in one DB round trip to increase performance?
Sure, just wrap up your three counts in a POCO or anonymous type:
using (var invoices = new AccountingEntities())
{
var c = (from i in invoices.Transactions
select new
{
c1 = invoices.Count(i=>i.Type = 0),
c2 = invoices.Count(i=>i.Type = 1),
c3 = invoices.Count(i=>i.Type = 2)
}).Single();
}
Also, dispose your context, as I show.
To aggregate arbitrary subqueries, use a dummy single-row result set from which you nest the desired subqueries. Assuming db represents your DbContext, the code to count invoice types will look like this:
var counts = (
from unused in db.Invoices
select new {
Count1 = db.Invoices.Count(i => i.Type == 0),
Count2 = db.Invoices.Count(i => i.Type == 1),
Count3 = db.Invoices.Count(i => i.Type == 2)
}).First();
If the want to generically get a count of all types, use grouping:
var counts =
from i in db.Invoices
group i by i.Type into g
select new { Type = g.Key, Count = g.Count() };
I have the following action
public ActionResult ViewModelProducts()
{
var listOfProductsBuy = db.ProductsBuy.Select(x => new ProductBuyViewModel
{
Id = x.Id,
Title = x.Title,
ProductBuyId = x.Id,
Author = x.Author,
MasterImageUrl = x.Images.FirstOrDefault().Url,
Price = x.Price,
Values = x.Value,
}).ToList();
var listOfProductsRent = db.ProductsRent.Select(y => new ProductRentViewModel
{
Id = y.Id,
Title = y.Title,
MasterImageUrl = y.ImagesRent.FirstOrDefault().Url,
ProductRentId = y.Id,
Author = y.Author,
Period = y.Period.PeriodOfTime,
Price = y.Price,
Values = y.Value,
}).ToList();
var listOfProductsSearch = db.ProductSearches.Select(z => new ProductSearchViewModel
{
Id = z.Id,
Title = z.Title,
ProductSearchId = z.Id,
Author = z.Author,
MasterImageUrl = z.ImagesSearch.FirstOrDefault().Url,
Price = z.Price,
Values = z.Value,
}).ToList();
var viewModel = new AllProductsViewModel { ProductBuy = listOfProductsBuy, ProductRent = listOfProductsRent, ProductSearch = listOfProductsSearch};
return View(viewModel);
}
I want to implement paging for more than one viewmodel. If there is way with PagedList it will be better, but if there is not it will be ok too.
In order to add paging, you can install PagedList.MVC Nuget package. You can see the exact step by step procedure to add it on Microsoft website here. Check out the section named: "Add Paging to the Students Index Page". Hope this helps.
int year = 2009; // get summ of TONS2009 column
var query = from ODInfo in DataContext.CIMS_TRUCKS
where pLocationIDs.Contains(ODInfo.OID)
group ODInfo by ODInfo.OID into g
select new
{
OID = g.Key,
TotalTons = g.Sum( ODInfo => ODInfo.TONS2009)
};
IN the expression 'ODInfo => ODInfo.TONS2009', how do I change TONS2009 to TONS2010 or TONS2011 based on the method parameter 'int year' ?
K06a's answer is close but won't work server-side. Try this:
IEnumerable<OutputType> myQuery(IEnumerable<InputType> data, Expression<Func<InputType,decimal>> expr)
{
return from ODInfo in DataContext.CIMS_TRUCKS
where pLocationIDs.Contains(ODInfo.OID)
group ODInfo by ODInfo.OID into g
select new OutputType
{
OID = g.Key,
TotalTons = g.AsQueryable().Sum(expr)
};
}
var query = myQuery(DataContext.CIMS_TRUCKS, ODInfo => ODInfo.TONS2009);
I haven't tried this, but did something similar here.
UPDATE
If you really need to translate input strings (like "2009") to expressions, it's still possible:
string year = "2009";
Type ODInfoType = typeof(ODINFOTYPE); // substitute with the type of ODInfo
ParameterExpression pe = ParameterExpression.Parameter(ODInfoType, "ODInfo");
MemberInfo mi = ODInfoType.GetProperty("TONS" + year);
MemberExpression me = Expression.MakeMemberAccess(pe, mi);
var expr = Expression.Lambda<Func<ODINFOTYPE, decimal>>(me, pe);
Be aware that this is a patch to the extremly evil structure of your database.
You can try something like that:
TotalTons = g.Sum( ODInfo => (year == 2009) ? ODInfo.TONS2009 : ((year == 2010)
? ODInfo.TONS2010 : ODInfo.TONS2011))
Or make it more readable and use { } to split that lambda expression into more then one line and use eg. switch statement.
The best solution is to break this up into multiple querys that you can compose to a final query:
int year = 2009; // get summ of TONS2009 column
var odInfos =
year == 2009 ? DataContext.CIMS_TRUCKS.Select(x => new { x.OID, TONS = x.TONS2009 })
year == 2010 ? DataContext.CIMS_TRUCKS.Select(x => new { x.OID, TONS = x.TONS2010 })
year == 2011 ? DataContext.CIMS_TRUCKS.Select(x => new { x.OID, TONS = x.TONS2011 })
: null;
var query = from ODInfo in odInfos
where pLocationIDs.Contains(ODInfo.OID)
group ODInfo by ODInfo.OID into g
select new
{
OID = g.Key,
TotalTons = g.Sum(ODInfo => ODInfo.TONS)
};
This will specialize to three possible queries at runtime, thereby giving the best possible performance. It is better than a case-switch.
Try this way:
IEnumerable<OutputType> myQuery(IEnumerable<InputType> data, Func<InputType,decimal> func)
{
return from ODInfo in data
where pLocationIDs.Contains(ODInfo.OID)
group ODInfo by ODInfo.OID into g
select new OutputType
{
OID = g.Key,
TotalTons = g.Sum(func)
};
}
var query = myQuery(DataContext.CIMS_TRUCKS, ODInfo => ODInfo.TONS2009);
Using DynamicLinq which works with EF also:
int year = 2009; // get summ of TONS2009 column
var query = from ODInfo in DataContext.CIMS_TRUCKS
where pLocationIDs.Contains(ODInfo.OID)
group ODInfo by ODInfo.OID into g
select g;
var projectedGroups = query.Select("new (Key as OID, Sum(TONS" + year + ") as TotalTons)");