I'd like to implement a module for filtering and paging. I understand that to suceed I had to use Dynamic Linq or Reflection, so I started trying to make it work .. but since the field that contains the text to be filtered in a one to many relationship EF not like it.
This code work fine .. but is static :
List<Domain.Entities.Action> actions = db.Actions.Include("Menus").Include("ActionDetails")
.Where(x => x.ActionDetails.Any(y => y.Language.Culture == _currentCulture))
.OrderBy(y => y.ActionDetails.Select(z => z.Title).Max()).Skip((pager.Index - 1) * pager.Take).Take(pager.Take)
.ToList();
I want the
.Select(z => z.Title)
Dynamic..
Can someone help me .. I Try a lot of thing .. but no sucess
Ju.
In order to accomplish this you need to pass in a parameter of Funt<Action, TResultType> searchCriteria
Not sure what your method signature is like but this would work if you plan on returning a List<string>
public List<string> PerformSearch(Func<Action, string> selectCriteria)
{
return db.Actions.Include("Menus").Include("ActionDetails")
.Where(x => x.ActionDetails.Any(y => y.Language.Culture == _currentCulture))
.OrderBy(y => y.ActionDetails.Select(**selectCriteria**).Max())
.Skip((pager.Index - 1) * pager.Take).Take(pager.Take)
.ToList();
}
Related
I've got a table
Application
ApplicationID,
NAme
ApplicationSteps
AplicationStepID,
AplicationID,
StepID
ApplicationStepCriterias
ApplicationStepID,
CriteriaID
So I've got one SelectedCriteriaID - a user choose from a dropdown one criteria and he wants all the applications which has this SelectedCriteriaID in the table ApplicationStepCriterias
I tried
var ds = context.Applications
.Where(a => a.ApplicationSteps
.Select(x=>x.ApplicationStepCriterias
.Select(t=>t.CriteriaId))
.Contains(SelectesdCriteria));
But as I have as result IEnumerable<IEnumerable<int>> I cannot use Contains
Just I get a list of all the CriteriaIds for each ApplicationStep(also a sequence). Just I cannot think of way to get in one list all the CriteriIds.
First, let me try to get the names right. This is not a pure many-to-many association, because the junction class is part of the class model. It is what I unofficially call a 1-n-1 association. So you have
Application -< ApplicationSteps >- ApplicationStepCriterias
I'd strongly recommend to use singular names for your classes ...
Application -< ApplicationStep >- ApplicationStepCriterion
... so you can use plural for collection property names without getting confused.
If I'm right so far, you query should be
context.Applications
.Where(a => a.ApplicationSteps
.Any(x => selectedCriteria
.Contains(x.ApplicationStepCriterion.CriteriaId));
(and I'd also prefer CriterionId, probably referring to a Criterion class)
You may try something like this:
var applicationStepIds = context.ApplicationStepCriterias
.Where(i => i.CriteriaID == selectedCriteria)
.Select(i => i.ApplicationStepID)
.Distinct();
var applicationIds = context.ApplicationSteps
.Where(i => applicationStepIds.Contains(i.AplicationStepID))
.Select(i => i.AplicationID)
.Distinct();
var result = context.Applications.Where(i => applicationIds.Contains(i.ApplicationId));
Have the following hierarchy:
AvailabilityCounts can have many MemberCounts
Each MemberCount can have one Booking
I need a linq statement that will select all AvailabilityCounts which have at least one child MemberCount for which there is no associated Booking.
I've got this far:
var test = rep.AvailabilityCounts_Get()
.Where(a => a.MemberCounts
.Where(m => m.Bookings.Any())
.Count() > 0);
This works when the AvailabilityCount has multiple MemberCounts, but ends up with opposite results when there's only one MemberCount.
Apologies for using other people's brains to do my work, but struggling to see the logic in this.
Try this one:
var test = rep.AvailabilityCounts_Get().Where(a => a.MemberCounts
.Any(m => !m.Bookings.Any()));
I would say an Any() and a not Any() should do what you want.
rep.AvailabilityCounts_Get.Where(m => m.MemberCounts.Any(x => !x.Bookings.Any());
I have a List<Locations> that will be filtered to yield a set of results relevant to a search term.
At the moment, I tried these 'search results' by filtering with the following:
return locations.Where(o => o.Name.Contains(term)).Take(10).ToList();
Problem
If I were to enter 'Chester' as the search term, I will never see the item "Chester" despite it existing in the locations list. The reason for this is that there are 10 or more other items in the list that contain the String "Chester" in their name (Manchester, Dorchester etc.).
How can I use LINQ to first of all take the results that start with the search term?
What I've Got So Far
var startsWithList = list.Where(o => o.Name.StartsWith(term)).Take(10).ToList();
var containsList = list.Where(o => o.Name.StartsWith(term) && !startsWithList.Contains(o)).Take(10 - startsWithList.Count).ToList();
return startsWithList.AddRange(containsList);
I don't like the above code at all. I feel like this should be achieved in one Where as opposed to performing two Where and Take's and combining the two lists.
just order ascending before Take, putting a lower value for items starting with term.
return locations.Where(o => o.Name.Contains(term))
.OrderBy(m => m.Name.StartsWith(term) ? 0 : 1)
//or OrderByDescending(m => m.Name.StartsWith(term))
.Take(10)
.ToList();
adapted with the improvement of MikeT (exact match before StartsWith), you could just do
return locations.Where(o => o.Name.Contains(term))
.OrderBy(m => m.Name.StartsWith(term)
? (m.Name == term ? 0 : 1)
: 2)
.Take(10)
.ToList();
I have created a new github project that uses expression trees to search for text in any number of properties
It also has a RankedSearch() method which returns the matching items with the number of hits for each record meaning you can do the following:
return locations.RankedSearch(term, l => l.Name)
.OrderByDescending(x => x.Hits)
.Take(10)
.ToList();
If you wanted you could search accross multiple properties
return locations.RankedSearch(term, l => l.Name, l => l.City)
... or for multiple terms,
return locations.RankedSearch(l => l.Name, term, "AnotherTerm" )
... or for both multiple properties and multiple terms
return locations.RankedSearch(new[]{term, "AnotherTerm"},
l => l.Name,
l => l.City)
Checkout this post for more information on the SQL generated and other usages:
http://jnye.co/Posts/27/searchextensions-multiple-property-search-support-with-ranking-in-c-sharp
You can download this as a nuget package to:
https://www.nuget.org/packages/NinjaNye.SearchExtensions/
Raphaël's Solution will work but if you were say searching for Warwick you could find that it might not put Warwick the top of the list if Warwickshire is also a possible location,using the scores you can also extend this infinitely with more matching methods, as well as tweaking the score values to refine your search order
return locations.Select(l => New {SearchResult=l,
Score=(L.Name == Term ?
100 :
l.Name.StartsWith(term) ?
10 :
l.Name.Contains(term) ?
1 :
0
)})
.OrderByDescending(r=>r.Score)
.Take(10)
.Select(r => r.SearchResult);
note i would probably do this by making a Match method and do the logic in there rather than in the linq like i did above so it would just be
return locations.OrderByDescending(Match).Take(10);
All Solutions will work but the better score can gain more easier as below
return locations.Where(o => o.Name.Contains(term))
.OrderBy(m => m.Name.IndexOf(term))
.Take(10)
.ToList();
as a result each name that contain term at nearest to start, show first.
What about this?
return locations.Where(o => o.Name.Contains(term))
.OrderBy(m => m.Length)
.Take(10)
.ToList();
SFC.OrderFormModifiedMonitoringRecords
.SelectMany(q => q.TimeModify, w => w.DateModify)
.Distinct()
.OrderBy(t => t)
.SelectMany(t => new { RowID = t.rowID, OFnum = t.OFNo });
It's Error did i missed something or is it Completely Coded The Wrong Way? After this i'm gonna use this on a Foreach method to gather up multiple data without the duplicates.
The delegate you pass to SelectMany must return an IEnumerable and is for collapsing multiple collections into one. So yes, something's definitely wrong here. I think you've confused it with Select which simply maps one collection to another.
Without knowing what your goal is, it's hard to know exactly how to fix it, but I'm guessing you want something like this:
SFC.OrderFormModifiedMonitoringRecords
.OrderBy(t => t.DateModify)
.ThenBy(t => t.TimeModify)
.Select(t => new { RowID = t.rowID, OFnum = t.OFNo })
.Distinct();
Or in query syntax:
(from t in SFC.OrderFormModifiedMonitoringRecords
orderby t.DateModify, t.TimeModify
select new { RowID = t.rowID, OFnum = t.OFNo })
.Distinct();
This will order the records by DateModify then by TimeModify, select two properties, rowID and OFNo and return only distinct pairs of values.
I have a method that returns data from an EF model.
I'm getting the above message, but I can't wotk our how to circumvent the problem.
public static IEnumerable<FundedCount> GetFundedCount()
{
var today = DateTime.Now;
var daysInMonth = DateTime.DaysInMonth(today.Year, today.Month);
var day1 = DateTime.Now.AddDays(-1);
var day31 = DateTime.Now.AddDays(-31);
using (var uow = new UnitOfWork(ConnectionString.PaydayLenders))
{
var r = new Repository<MatchHistory>(uow.Context);
return r.Find()
.Where(x =>
x.AppliedOn >= day1 && x.AppliedOn <= day31 &&
x.ResultTypeId == (int)MatchResultType.Accepted)
.GroupBy(x => new { x.BuyerId, x.AppliedOn })
.Select(x => new FundedCount(
x.Key.BuyerId,
x.Count() / 30 * daysInMonth))
.ToList();
}
}
FundedCount is not an EF enity, MatchHistory is, so can't understand why it is complaining.
All advice appreciated.
The reason it is complaining is because it doesn't know how to translate your Select() into a SQL expression. If you need to do a data transformation to a POCO that is not an entity, you should first get the relevant data from EF and then transform it to the POCO.
In your case it should be as simple as calling ToList() earlier:
return r.Find()
.Where(x => x.AppliedOn >= day1 && x.AppliedOn <= day31 &&
x.ResultTypeId == (int)MatchResultType.Accepted)
.GroupBy(x => new { x.BuyerId, x.AppliedOn })
.ToList() // this causes the query to execute
.Select(x => new FundedCount(x.Key.BuyerId, x.Count() / 30 * daysInMonth));
Be careful with this, though, and make sure that you're limiting the size of the data set returned by ToList() as much as possible so that you're not trying to load an entire table into memory.
Message is clear : linq to entities doesn't support objects without a parameterless ctor.
So
Solution1
enumerate before (or use an intermediate anonymous type and enumerate on that one)
.ToList()
.Select(x => new FundedCount(
x.Key.BuyerId,
x.Count() / 30 * daysInMonth))
.ToList();
Solution2
add a parameterless ctor to your FundedCount class (if it's possible)
public FundedCount() {}
and use
.Select(x => new FundedCount{
<Property1> = x.Key.BuyerId,
<Property2> = x.Count() / 30 * daysInMonth
})
.ToList();
It's complaining because it can't convert references to FundedCount to SQL statements.
All LINQ providers convert LINQ statements and expressions to operations that their target can understand. LINQ to SQL and LINQ to EF will convert LINQ to SQL, PLINQ will convert it to Tasks and parallel operations, LINQ to Sharepoint will convert it to CAML etc.
What happens if they can't do the conversion, depends on the provider. Some providers will return intermediate results and convert the rest of the query to a LINQ to Objects query. Others will simply fail with an error message.
Failing with a message is actually a better option when talking to a database. Otherwise the server would have to return all columns to the client when only 1 or 2 would be actually necessary.
In your case you should modify your select to return an anonymous type with the data you want, call ToList() and THEN create the FundedCount objects, eg:
.Select( x=> new {Id=x.Key.BuyerId,Count=x.Count()/30 * daysInMonth)
.ToList()
.Select(y => new FundedCount(y.Id,y.Count))
.ToList();
The first ToList() will force the generation of the SQL statement and execute the query that will return only the data you need. The rest of the query is actually Linq to Objects and will get the data and create the final objects
I had the same exception in GroupBy. I found that the exception "Only parameterless constructors and initializers are supported in LINQ to Entities" is not 100% accurate description.
I had a GroupBy() in my "Linq to EntityFramework query" which used a struct as a Key in GroupBy. That did not work. When I changed that struct to normal class everything worked fine.
Code sample
var affectedRegistrationsGrouped = await db.Registrations
.Include(r => r.Person)
.Where(r =>
//whatever
)
.GroupBy(r => new GroupByKey
{
EventId = r.EventId,
SportId = r.SportId.Value
})
.ToListAsync();
...
...
// this does not work
private struct GroupByKey() {...}
// this works fine
private class GroupByKey() {...}