I am in the process of learning ReactiveUI and I am starting with commands
I have trouble translating the code for this RelayCommand to the equivalent ReactiveCommand
GodkendeBilagCommand = new RelayCommand<AdminUdbetalingsKvartal>(OnGodkendeBilag, GodkendeBilagCanExeute);
this is the code for GodkendeBilagCanExeute:
private bool GodkendeBilagCanExeute(AdminUdbetalingsKvartal kvartal)
{
return kvartal != null && kvartal.KanGodkendeBilag && !IsBusy;
}
How about this:
var canExecute = this.WhenAny(x => x.kvartal.KanGodkendeBilag, x => x.IsBusy,
(bilag, busy) => bilag.Value && !busy.Value);
GodkendeBilagCommand = ReactiveCommand.Create(canExecute);
Related
Linq has always befuddled me. I am trying to extract all controls from an ASP.Net form page where the ID of the control contains a specific string. The control collection is hierarchical and I want to return any matching controls from all levels. Am I anywhere in the ballpark here? I could really use some help/education. The collection parameter is the collection of controls from the page and controlID is the text I am searching for.
public static Control FindControlsByControlID(ControlCollection collection, string controlID)
{
IEnumerable<Control> controls = collection.Cast<Control>();
IEnumerable<Control> matchedControls = controls
.SelectMany(p => p.Controls.Cast<Control>()
.SelectMany(c => c.Controls.Cast<Control>())
.Where(d => d != null ? d.ID != null ? d.ID.Contains(controlID) : false : false))
.Where(a => a != null ? a.ID != null ? a.ID.Contains(controlID) : false : false);
ConcurrentQueue<Control> cq;
if (matchedControls != null)
cq = new ConcurrentQueue<Control>(matchedControls);
else
return null;
...
Thanks in advance!
Use an extension method to get all child controls:
public static class ControlExt {
public static IEnumerable<Control> AndSubControls(this Control aControl) {
var work = new Queue<Control>();
work.Enqueue(aControl);
while (work.Count > 0) {
var c = work.Dequeue();
yield return c;
foreach (var sc in c.Controls.Cast<Control>()) {
yield return sc;
if (sc.Controls.Count > 0)
work.Enqueue(sc);
}
}
}
}
Now you can test all the subcontrols in your ControlCollection:
IEnumerable<Control> matchedControls = controls.SelectMany(c => c.AndSubControls())
.Where(a => a != null && a.ID != null && a.ID.Contains(controlID));
I have a to add a specific requirement in a piece of code already implemented.
The data structure is something of this sort:
public class Module
{
public string Type;
public string ID;
public List<Point> Points = new List<Point>();
}
public class Point
{
public string Type;
public string Location;
public string Connection;
}
Originally LINQ was used to return all modules which certain characteristics
List<Module> miList = Modules.Where(m => m.Type != null
&& m.ID == "A"
&& m.Points.Where(t => t.Connection == ""
&& SimilarPoint(t.Type, x).ToList())
.Count() > 0)
.ToList();
with x an input to the function. The new requirement dictates that the modules returned shall all have points with Connection equal to "" and the same value in the Location field.
It seemed to me that the SelectMany could be used to this end, but I am not getting what I expected.
How should the function above be modified?
Thanks in advance
Not exactly sure what the SimilarPoint(t.Type, x) does here.
May be you should try something like this and find out if it works for you -
var resultSet = Modules.Where(m => !string.IsNullOrEmpty(m.Type) && m.ID.Equals("A"))
.Select(n =>
new Module {
Type=n.Type,
ID=n.ID,
Points= n.Points.Where(p => String.IsNullOrEmpty(p.Connection) && String.IsNullOrEmpty(p.Location)).ToList()
})
.ToList();
You said all the returned modules have the same Location, but that doesn't explain how you select which Location so I arbitrarily picked the first matching module's location:
var miQuery1 = Modules.Where(m => m.Type != null
&& m.ID == "A"
&& m.Points.Where(t => t.Connection == ""
&& SimilarPoint(t.Type, x).ToList()).Count() > 0)
.Where(m => m.Points.All(p => p.Connection == ""));
var miQuery2 = miQuery1.Where(m => m.Location == miQuery1.First().Location);
List<Module> miList = miQuery2.ToList();
Is there anyway around this error? I'd like to reuse the same lamba expression in other queries instead of having duplication. Can LinqKit or other linq expression do this?
Error
LINQ to Entities does not recognize the method 'Boolean GetEvent(Tournaments.Data.Entities.Event, System.String)' method, and this method cannot be translated into a store expression.
Code
public MobileEventDetailModel GetDetails(string applicationId)
{
var #event = (from e in _eventsRepository.DataContext.Events.Include(q => q.Assets.Select(a => a.Asset))
where GetEvent(e, applicationId)
select new
{
e.Id,
e.EventParent.Name,
LogoId = (from a in e.Assets
where a.Type == EventAssetType.Logo
select a.AssetId).FirstOrDefault()
}).FirstOrDefault();
return new MobileEventDetailModel
{
Id = #event.Id,
Name = #event.Name,
Logo = string.Format("{0}{1}{2}", Config.BaseUrl, Config.ImagesPath, #event.LogoId)
};
}
public bool GetEvent(Event #event, string applicationId)
{
return #event.Active && #event.Visible && #event.MobileEventApplications.Any(m =>
m.MobileApplication.ApplicationId == applicationId &&
(!m.MobileApplication.ActivationLength.HasValue || EntityFunctions.AddDays(DateTime.Now, 1) < EntityFunctions.AddMonths(m.MobileApplication.DateActivated, m.MobileApplication.ActivationLength.Value)));
}
You need to use an Expression:
public MobileEventDetailModel GetDetails(string applicationId)
{
var event = _eventsRepository.DataContext.Events.Include(q => q.Assets.Select(a => a.Asset))
.Where(GetEvent(applicationId))
.Select(a => new
{
a.Id,
a.EventParent.Name,
LogoId = (from b in a.Assets
where b.Type == EventAssetType.Logo
select b.AssetId).FirstOrDefault()
}).FirstOrDefault();
return new MobileEventDetailModel
{
Id = event.Id,
Name = event.Name,
Logo = string.Format("{0}{1}{2}", Config.BaseUrl, Config.ImagesPath, event.LogoId)
};
}
public Expression<Func<Event, bool>> GetEvent(int applicationId)
{
return = a => a.Active
&& a.Visible
&& a.MobileEventApplications
.Any(m => m.MobileApplication.ApplicationId == applicationId
&& (!m.MobileApplication.ActivationLength.HasValue
|| EntityFunctions.AddDays(DateTime.Now, 1)
< EntityFunctions
.AddMonths(m.MobileApplication.DateActivated, m.MobileApplication.ActivationLength.Value)
)
);
}
Update: Sorry it was late the other night, the changed version is hopefully more what you were looking for.
I wrote this awesome code that I am having trouble using now.
Currently working example:
complete item = ReliableExecution.RetryWithExpression<complete, complete>(u => u.FirstOrDefault(x => x.str_en == segment));
and this is a part of the RetryWithExpression code:
public static TValue RetryWithExpression<T, TValue>(Func<ObjectSet<T>, TValue> func, Int32 retryInfiniteLoopGuard = 0)
where T : class
{
RetryPolicy policy = RetryPolicyProvider.GetSqlAzureRetryPolicy();
using (DDEntities dataModel = new DDEntities())
{
var entitySet = dataModel.CreateObjectSet<T>();
...
var query = policy.ExecuteAction(() => (func(entitySet)));
...
Now my question is how to change the above select query to do SELECT * ?
I did try this but it tells me things about errors I don't understand:
complete item = ReliableExecution.RetryWithExpression<complete, complete>(u => u.Select(x => x.str_en != ""));
IQueryable<complete> items = ReliableExecution.RetryWithExpression<complete, IQueryable<complete>>(u => u.Where(x => x.str_en != "")); ?
While working on a personal project I wanted a simple service to extract items out of Outlook and host in WCF in a "RESTful" design. In the process I came up with this rather beastly class.
What other scary linq code have people have seen?
public IQueryable<_AppointmentItem> GetAppointments(DateTime date)
{
var dayFlag = (OlDaysOfWeek)(int)Math.Pow(2, (int)date.DayOfWeek);
return
OlDefaultFolders.olFolderCalendar.GetItems<_AppointmentItem>()
.Select(a => new
{
Appointment = a,
RecurrencePattern = a.IsRecurring ?
a.GetRecurrencePattern() : null
})
.Where(a =>
a.Appointment.Start.Date <= date &&
(
(a.RecurrencePattern == null &&
a.Appointment.End.Date >= date) ||
(
a.RecurrencePattern != null &&
(
(a.RecurrencePattern.DayOfMonth == 0 ||
a.RecurrencePattern.DayOfMonth == date.Day) &&
(a.RecurrencePattern.DayOfWeekMask == 0 ||
((a.RecurrencePattern.DayOfWeekMask &
dayFlag) != 0)) &&
(a.RecurrencePattern.MonthOfYear == 0 ||
a.RecurrencePattern.MonthOfYear == date.Month)
)
)
)
)
.Select(a => a.Appointment);
}
[OperationContract()]
[WebGet(
UriTemplate = "/appointments/{year}/{month}/{day}",
RequestFormat = WebMessageFormat.Xml,
ResponseFormat = WebMessageFormat.Xml,
BodyStyle = WebMessageBodyStyle.Bare
)]
[ContentType("text/xml")]
public XElement ListAppointments(string year, string month, string day)
{
try
{
int iYear, iMonth, iDay;
int.TryParse(year, out iYear);
int.TryParse(month, out iMonth);
int.TryParse(day, out iDay);
if (iYear == 0) iYear = DateTime.Now.Year;
if (iMonth == 0) iMonth = DateTime.Now.Month;
if (iDay == 0) iDay = DateTime.Now.Day;
var now = new DateTime(iYear, iMonth, iDay).Date; // DateTime.Now;
return GetAppointments(now).ToXml();
}
catch (System.Exception ex)
{
return new XElement("exception", ex.ToString());
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;
using Microsoft.Office.Interop.Outlook;
namespace WhitedUS.ServiceModel.Office.Linq
{
public static class OutlookUtilities
{
public static IQueryable<T> GetItems<T>(
this OlDefaultFolders defaultFolderType)
{
return
new ApplicationClass()
.Session
.GetDefaultFolder(defaultFolderType)
.Items
.OfType<T>()
.AsQueryable();
}
public static XElement ToXml<T>(this IEnumerable<T> input)
{
if (input == null)
return null;
Type typ = typeof(T);
var root = XName.Get(typ.Name.Trim('_'));
return new XElement(root,
input
.Select(x => x.ToXml<T>())
.Where(x => x != null)
);
}
public static XElement ToXml<T>(this object input)
{
if (input == null)
return null;
Type typ = typeof(T);
var root = XName.Get(typ.Name.Trim('_'));
return new XElement(root,
typ.GetProperties()
.Where(p => p.PropertyType.IsValueType ||
p.PropertyType == typeof(string))
.Select(p => new { Prop = p, Getter = p.GetGetMethod() })
.Where(p => p.Getter != null)
.Select(p => new { Prop = p.Prop, Getter = p.Getter,
Params = p.Getter.GetParameters() })
.Where(p => (p.Params == null || p.Params.Count() <= 0))
.Select(p => new { Name = p.Prop.Name,
Value = p.Getter.Invoke(input, null) })
.Where(p => p.Value != null)
.Select(p => new XAttribute(XName.Get(p.Name), p.Value))
);
}
}
}
Also see: What is the worst abuse you’ve seen of LINQ syntax?
A fully LINQified RayTracer is pretty scary.
Actually, the scariest Linq query I ever saw was my first one. It was just familiar enough to make me think I understood it and just different enough to make me doubt that I really did.