CODEWITHSUNDEEP
c#linqentity-frameworklinq-to-entities
user1477388
user1477388

Reputation: 21430

How to Get Closest Location in LINQ to Entities

I am trying to get the closest location via my LINQ query:

var coord = new GeoCoordinate(loc.Latitude, loc.Longitude);
var nearest = ctx.Locations
                 .Select(x => new LocationResult {
                     location = x,
                     coord = new GeoCoordinate(x.Latitude.GetValueOrDefault(),
                                               x.Longitude.GetValueOrDefault())
                 })
                 .OrderBy(x => x.coord.GetDistanceTo(coord))
                 .First();

return nearest.location.Id;

However, I am getting the following error:

Only parameterless constructors and initializers are supported in LINQ to Entities.

I have tried Googling this but I am still not sure how to fix it. What is a parameterless constructor?

Upvotes: 1

Views: 2040

Answers (2)

It'sNotALie.
It'sNotALie.

Reputation: 22794

You need to try this instead:

var coord = new GeoCoordinate(loc.Latitude, loc.Longitude);
                var nearest = ctx.Locations
                    .Select(x => new LocationResult {
                        location = x,
                        coord = new GeoCoordinate { Latitude = x.Latitude ?? 0, Longitude = x.Longitude ?? 0 }
                    })
                    .OrderBy(x => x.coord.GetDistanceTo(coord))
                    .First();

                return nearest.location.Id;

Upvotes: 2

Sachin Kainth
Sachin Kainth

Reputation: 46750

The problem is this line

new GeoCoordinate(x.Latitude.GetValueOrDefault(), x.Longitude.GetValueOrDefault())

This is using a constructor with a parameter becuase the GeoCoordiante class's constructor is called with a couple of parameters.

A paramaterless constructor is a constructor for a type that does not take any parameters.

Upvotes: 0

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