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How about something like:
int count = yourDbContext.yourEntityCollection.Where(entity => entity.ID == 1 && entity.FieldA != null).Count();
You have just been Sharapova'd.
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Or, more simply:
int count = yourDbContext.yourEntityCollection.Count(entity => entity.ID == 1 && entity.FieldA != null);
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Not sure about Linq to SQL, but (for Linq to objects and XML) I have always found Where(predicate).Count() to be performing better than .Count(predicate).
--EDIT
Here's a StackOverflow question[^] that might interest you.
You have just been Sharapova'd.
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The optimizations only apply to in-memory LINQ queries (LINQ to Objects and LINQ to XML). With LINQ to SQL and Entity Framework, both versions should produce an identical SQL query.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Indeed, they should. But I have always used the Where(predicate).Count() version, so that came implicitly when I posted the answer.
You have just been Sharapova'd.
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This is the code that I am looking to get a Count of complexQuery.
string refName = entity.GetAttributeValue<string>("contractorname");
var complexQuery = (from c in orgContext.CreateQuery<contractorframe>()
join e in orgContext.CreateQuery<dcc_eval>()
on c.ContractorName equals e.RegardingObjectId.ToString()
where e.RegardingObjectId.ToString() == refName
and e.QW Is Not Null)
modified 15-Oct-15 10:27am.
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macca24 wrote: I am looking to get a Count of complexQuery
Not sure what you mean by that, but if your complexQuery is already working, then you can simply use the Count() method:
int complexQueryCount = (from c in orgContext.CreateQuery<contractorframe>()
join e in orgContext.CreateQuery<dcc_eval>()
on c.ContractorName equals e.RegardingObjectId.ToString()
where e.RegardingObjectId.ToString() == refName
and e.QW Is Not Null).Count();
You have just been Sharapova'd.
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int complexQuery = (from e in mycontext.CreateQuery<new_eval>()
where e.new_QW1 != null
select e.new_QW1).Count();
if (complexQuery < 1)
{
var newQuery = "HasData";
entity.Attributes.Add("new_testcomplexquery", newQuery);
}
else
{
var newQueryToo = "Blank";
entity.Attributes.Add("new_testcomplexquery", newQueryToo);
}
I want to use the results of complexQuery in an If statement but the value of complexQuery doesnt appear to be getting picked up. Anyone know why?
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I am not sure what you are trying to do, but shouldn't your if condition be reversed? i.e. it "HasData" if complexQuery > 0 and it's "Blank" if complextQuery == 0. Try this:
if (complexQuery != 0)
{
var newQuery = "HasData";
entity.Attributes.Add("new_testcomplexquery", newQuery);
}
else
{
var newQueryToo = "Blank";
entity.Attributes.Add("new_testcomplexquery", newQueryToo);
}
You have just been Sharapova'd.
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I have a serial port controller (for sensing any object that passes through its transport module) connected to USB. It responses with either 0 or 1 after input command "t" when it senses any dropping or no dropping of object through the transport. The page CshDeposit5 contains the code. Start.xaml is the page the activity starts and ends up in CshDeposit5.xaml. TmpErrorMsg and TmpMsg are the pages to show the user what happened. Everything runs fine for the first time. But when it tries to come to this CshDeposit5.xaml 2nd time it throws exception on the follwoing highlighted codes:
CshDeposit5.xaml.cs
--------------------------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.IO.Ports;
using System.Windows.Threading;
namespace NWCDM
{
public partial class CshDeposit5 : Page
{
private System.Windows.Threading.DispatcherTimer dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
private static int i;
public CshDeposit5()
{
InitializeComponent();
}
private void Page_Loaded(object sender, RoutedEventArgs e)
{
i = Global.xDropTime;
TimeLeft.Text = i.ToString();
dispatcherTimer.Tick += dispatcherTimer_Tick;
dispatcherTimer.Interval = new TimeSpan(0, 0, 1);
Global.xController.WriteLine("t");
dispatcherTimer.Start();
SerialPort sp2 = Global.xController;
sp2.DataReceived += new SerialDataReceivedEventHandler(DataReceivedHandler );
}
public void DataReceivedHandler(object sender, SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
string indata = sp.ReadExisting();
Dispatcher.Invoke(DispatcherPriority.Send, new Action(() => DoTrans(indata)));
}
private void DoTrans(string x){
if (i >= 0)
{
if (x.IndexOf("1") >= 0)
{
dispatcherTimer.Stop();
Dispatcher.BeginInvoke(new System.Threading.ThreadStart(delegate
{
NavigationService.Navigate(new Uri("TmpMsg.xaml", UriKind.RelativeOrAbsolute));
}));
}
else
{
if (x.IndexOf("0") >= 0)
{
Dispatcher.BeginInvoke(new System.Threading.ThreadStart(delegate
{
NavigationService.Navigate(new Uri("TmpErrorMsg.xaml", UriKind.RelativeOrAbsolute));
}));
}
}
}
}
private void dispatcherTimer_Tick(object sender, EventArgs e)
{
if (i >= 0)
{
if (Global.VarLang == 0)
{
TimeLeft.Text = i.ToString();
}
i--;
}
else
{
dispatcherTimer.Stop();
Global.xController.WriteLine("r");
Dispatcher.BeginInvoke(new System.Threading.ThreadStart(delegate
{
NavigationService.Navigate(new Uri("TmpErrorMsg.xaml", UriKind.RelativeOrAbsolute));
}));
}
}
}
}
modified 14-Oct-15 4:31am.
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Please edit your question, remove the blank lines, add proper indentation, and add <pre lang="c#"></pre> tags around your code to make it more readable, like this:
public CshDeposit5()
{
InitializeComponent();
}
Next, you should use your debugger to identify exactly which variable is null when the exception is thrown.
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NavigationService.Navigate(new Uri("TmpMsg.xaml", UriKind.RelativeOrAbsolute)); throws the null exception. I tried the following,
NavigationService nav = NavigationService.GetNavigationService(this);
nav.Navigate(new Uri("TmpMsg.xaml", UriKind.RelativeOrAbsolute));
where nav variable is shown null.
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So you need to find out why NavigationService.GetNavigationService(this); is returning null rather than a valid object.
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Please note as I mentioned earlier it doesn't thro any null exception 1st time. I get this when CshDeposit5.xaml is called the 2nd time.
How do I find its returning null?
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Unfortunately that is the nature of code bugs, they only happen when you least expect them. The only way to track the problem is by debugging and testing. You should examine all the information in the exception including the stack trace, in order to try and find out what has happened leading up to the error.
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Good day.
Please fix the formatting. It makes it really hard to read, so I have not read through your code.
Anyway, the first thing that comes to mind is check that when you try to navigate to a XAML page a second time, the
NavigationService.Navigate method already has the page you are trying to navigate to in memory.
Something similar happened to me quote some time ago.
I fixed it by first checking if the page I wanted to navigate to was not already loaded into the NavigationService. If it was, I didn't do anything, else let the Navigation proceed.
Hope that helps.
Neill
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How do I check if the page is already loaded or not in WPF?
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Its been a while but a quick search leads me to using CurrentSource of the NavigationService.
Something like:
NavigationWindow.CurrentSource.ToString());
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Currentsource property not available
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Like I said, its only a possibility that that is causing your problem.
Do some research to try and figure out how to get the CurrentSource, we can't do everything for you.
Neill
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It means you don't have any clue to suggest. Thanks anyways.
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After reviewing some more, it is quite likely that the code is losing reference to the NavigationService object due to DoTrans() being run on a different thread.
But hey, maybe I just don't have any clue to suggest.
Good luck in finding the problem.
Neill
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I have the following code To get the prime numbers between a range of numbers, is this the best and fast method?
int[] NumberCollection = Enumerable.Range(startNum,Count).ToArray<int>();
string primeNumbers = string.Join(",", from number in NumberCollection
where (IsPrime(number)==true)
select number);
Where :
startNum is the starting number
Count is the number of numbers in the collection
IsPrimeis defined as follows:
private static bool IsPrime(int number)
{
for (int i = 2; i < number; i++)
if (number % i == 0) return false;
return true;
}
sujith karivelil
Microsoft Technology Associate
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No.
For starters, your loop is going to check each and every possible divisor from 2 on up: so if the number is 13, it will check 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.
Since you checked 2 to start with, it can't be divisible by any other even number - so why check them?
Then you would check 2, 3, 5, 7, 9, 11
But...since it's not divisible by 2, it isn't divisible by any number greater than number / 2 so why check 7, 9, 11?
Two simple changes, and you reduce the number of loops from 12, to 3...
I'd suggest that you tart by doing some reading: https://en.wikipedia.org/wiki/Primality_test[^] - there are much more efficient methods.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Ya, that's fine and good suggestion
sujith karivelil
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