Clash Royale CLAN TAG#URR8PPP

Pass property as parameter to create a filtering method with LINQ/C#?

Suppose I have these classes:

private class Model

public DateTime FirstDate get; set;
public DateTime SecondDate get; set;
public DateTime FinalDate get; set;
public string Name get; set;

private class Mommasan : Bandana

public DateTime RestDate get; set;
public DateTime TurboDate get; set;
public string Name get; set;



All dates need to be filtered up to 3 days. So how can I create a generic filtering method for the DateTime properties? Using IQueryable? I was hoping it would end up something like this:

DateTime

IQueryable

(Obviously will not compile, but I'm guessing the idea)

void DoSpecificFilter<T>(ref IQueryable<T> query, DateTimeProperty property)

DateTime today = today;
query = query.Where(a => property <= today && today <= property.AddDays(3);



So if I need to filter Models who are on their final date, something like:

Models

DoSpecificFilter<Model>(ref alreadyFilteredQuery, a => a.FinalDate);


and Mommasans who are on rest:

Mommasans

DoSpecificFilter<Mommasan>(ref alreadyFilteredQuery, a => a.RestDate);


Is this kind of thing possible at all or am I having the entirely wrong idea? Thanks!

2 Answers
2

Why not write an extension method on DateTime, and not look at the class at all? Something like ...

public static class Extensions

public static IQueryable<T> DoSpecificFilter<T>(this DateTime value, IQueryable<T> query)

DateTime today = DateTime.Now;
IQueryable<T> ret = query.Where(a => value <= today && today <= value.AddDays(3));
return ret;




You could work with DateTime-Selectors. For multiple DateTime fields you would have to chain them together. It would probably be easier to write an extention method for this:

DateTime

DateTime

public static class ExtentionMethods

public static IQueryable<T> DoSpecificFilter<T>(
this IQueryable<T> query,
Expression<Func<T, DateTime>> dateSelector,
DateTime filterValue,
bool blnTopLimit)




Then you could use it like this:

var query = queryableCollection
.DoSpecificFilter((a) => a.RestDate, DateTime.Today, false)
.DoSpecificFilter((a) => a.TurboDate, DateTime.Today, true);


Func

Expressions

Expression<Func<T, DateTime>>

bool

where T :

<T>

dateSelector(a)

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