topic Re: Convert Polygon to DbGeography in .NET Maps SDK Questions

Convert Polygon to DbGeography

AlexVelez — Thu, 08 Sep 2022 21:17:35 GMT

Hello

I need to convert a polygon geometry to System.Data.Entity.Spatial.DbGeography , I have been trying to do with something like that

StringBuilder text = new StringBuilder(); string firstPoint = string.Empty, textToAppend; var parts = ((Polygon)(geometry)).Parts; for (int i = 0; i < parts[0].Points.Count; i++) { var normalizedPoint = GeometryEngine.NormalizeCentralMeridian(parts[0].Points[i]); var projectedCenter = GeometryEngine.Project(normalizedPoint, SpatialReferences.Wgs84) as MapPoint; textToAppend = $"{projectedCenter.X} {projectedCenter.Y}"; textToAppend= textToAppend.Replace(',', '.'); textToAppend = $"{textToAppend},"; text.Append(textToAppend); if (string.IsNullOrWhiteSpace(firstPoint)) { firstPoint = $"{projectedCenter.X} {projectedCenter.Y}"; firstPoint = firstPoint.Replace(',', '.'); } } text.Append(firstPoint); var dbGeography=DbGeography.PolygonFromText($"POLYGON(({text}))", 4326);

And it works, but when i saved it to a SQL database on a column of type Geography, it does not work correctly.

What is the correct way to achieve this?

Thanks

Re: Convert Polygon to DbGeography

dotMorten_esri — Thu, 08 Sep 2022 21:41:31 GMT

You're better off going through the geometry builders than going through WKT which would be extremely slow. Perhaps this code snippet here will help: https://github.com/dotMorten/GeometryConversions/blob/master/src/GeometryConversions.Shared/System.Spatial/SystemSpatialConverter.CreateGeography.cs

Re: Convert Polygon to DbGeography

AlexVelez — Thu, 08 Sep 2022 23:20:07 GMT

Thanks for the reply

I was checking the code but its for convert to Microsoft.Spatial and i dont know what more to do to convert to System.Data.Entity.Spatial.DbGeography. Please help me

Re: Convert Polygon to DbGeography

dotMorten_esri — Fri, 09 Sep 2022 02:38:48 GMT

I don't know EF too well, but browsing their code it looks like it's just a wrapper around other spatial libraries, and there's some sort of provider that might give you access to the underlying sql geometry libraries.