CODEWITHSUNDEEP
c#linqjoin
bc291
bc291

Reputation: 1171

Error when trying to "where" on strongly typed list, error CS0103

I've got linq which joins two lists by id and returns strongly typed List:

   List<TestowaKlasaDlaLinq> linqlambda = ListDetailedData.Join(PlacesList, a => a.place.id, b => b.id, (a, b) =>
                new TestowaKlasaDlaLinq()
                {
                    Czas = a.startDate.TimeOfDay.ToString(),
                    Co = a.name,
                    Miasto = b.address.city,
                    Miejsce = a.organizer.designation
                }).ToList();

For now everything works. Problem appeared when I tried to filter that list e.g.:

   var onlyGdansk = linqlambda.Where(x => x.Miasto.Equals("Gdańsk")).Select(x => x).ToList();

That error came out: enter image description here

How is this possible that strongly field of strongly typed List of type "TestowaKlasaDlaLinq" doesnt exist in that context?

Upvotes: 3

Views: 542

Answers (2)

Harald Coppoolse
Harald Coppoolse

Reputation: 30492

A variant of Gauran Dave's answer: do not put the Equals function on the string in property Miasto, because that string could be null, but put the Equals function on the string "Gdańsk". You may be assert that "Gdańsk" is not null.

var onlyGdansk = linqlambda.Where(x => "Gdańsk".Equals(x)))
    .Select(x => x) // this one can be omitted
    .ToList();

Or consider using String.Equals(string, string), which IMHO is a bit more readable here:

var onlyGdansk = linqlambda.Where(x => String.Equals(x, "Gdańsk"))
    .Select(x => x) 
    .ToList()

Upvotes: 0

Gaurang Dave
Gaurang Dave

Reputation: 4046

I think, One of the x.Miasto value is null and that is the reason, it shows you this error. 

var onlyGdansk = linqlambda.Where(tkdl => tkdl.Miasto!=null && tkdl.Miasto.Equals("Gdańsk")).Select(dl => dl).ToList();

Upvotes: 3

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