Mapping the World with EF Core: Working with Spatial Data

Have you ever needed to store coordinates, track locations, or perform distance calculations in your database? Whether you’re building a ride-sharing app, a location-based service, or an interactive map, working with spatial data is essential.

Luckily, EF Core supports spatial data types, allowing you to store, query, and manipulate geographic data seamlessly. No more treating latitude and longitude as simple numbers—let’s bring real GIS (Geographic Information System) power to your EF Core apps!

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What is Spatial Data?

Spatial data represents geographic locations and features on the Earth’s surface. Instead of dealing with raw latitude/longitude values, spatial data provides rich functionality for working with points, lines, polygons, and even complex geometries.

Think of it like this:
Points – Represent single locations (e.g., a store location).
Lines – Define paths or routes (e.g., roads, trails).
Polygons – Represent areas (e.g., city boundaries, country borders).

Most modern databases, like SQL Server, PostgreSQL, and MySQL, provide native spatial data support, allowing you to run geospatial queries efficiently.

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Setting Up Spatial Data in EF Core

Before we start playing with coordinates, we need to set up EF Core to support spatial data.

1. Install the Required Packages

If you’re using SQL Server, you need the NetTopologySuite package, which enables spatial data support.

dotnet add package Microsoft.EntityFrameworkCore.SqlServer.NetTopologySuite

For PostgreSQL, install:

dotnet add package Npgsql.EntityFrameworkCore.PostgreSQL.NetTopologySuite

2. Configure DbContext to Use Spatial Support

Modify your DbContext configuration to enable NetTopologySuite:

public class AppDbContext : DbContext
{
    public DbSet<Location> Locations { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("Your_Connection_String", 
            x => x.UseNetTopologySuite()); // Enable spatial support
    }
}

This tells EF Core to use spatial capabilities when working with SQL Server (or PostgreSQL).

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Defining Spatial Data in EF Core

Now that EF Core is ready, let’s create an entity with a geographic location.

3. Create an Entity with Spatial Data

using NetTopologySuite.Geometries;

public class Location
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Point Coordinates { get; set; } // Stores latitude/longitude
}

What’s happening here?

• We import NetTopologySuite.Geometries to use spatial types.
• The Point type is used to store a geographic location (latitude & longitude).

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Storing and Querying Spatial Data

Now that we’ve defined our Location entity, let’s add some data!

4. Inserting Spatial Data

using NetTopologySuite.Geometries;

var location = new Location
{
    Name = "Central Park",
    Coordinates = new Point(-73.9654, 40.7829) { SRID = 4326 } // Longitude, Latitude
};

context.Locations.Add(location);
await context.SaveChangesAsync();

What is SRID = 4326?

• SRID (Spatial Reference Identifier) defines the coordinate system.
• 4326 is WGS 84, the standard for latitude/longitude (used by GPS).

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5. Querying Nearby Locations

Let’s say you want to find locations within 5 kilometers of a user:

using NetTopologySuite.Geometries;
using NetTopologySuite.Geometries.Prepared;

var userLocation = new Point(-73.9851, 40.7580) { SRID = 4326 }; // Times Square

var nearbyLocations = await context.Locations
    .Where(l => l.Coordinates.IsWithinDistance(userLocation, 5000)) // 5km radius
    .ToListAsync();

foreach (var location in nearbyLocations)
{
    Console.WriteLine($"Nearby: {location.Name}");
}

How does this work?

• IsWithinDistance() checks if a location is within 5000 meters (5km) of the user.
• This is way more efficient than manually filtering lat/lon values!

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Working with Polygons: Defining Regions

Let’s say you need to store city boundaries and check whether a location is inside a region.

6. Create a Polygon Entity

public class CityBoundary
{
    public int Id { get; set; }
    public string CityName { get; set; }
    public Polygon Area { get; set; } // Stores city boundary
}

7. Query Locations Inside a City

var newYorkBoundary = context.CityBoundaries
    .FirstOrDefault(c => c.CityName == "New York");

var locationsInNYC = await context.Locations
    .Where(l => newYorkBoundary.Area.Contains(l.Coordinates))
    .ToListAsync();

foreach (var location in locationsInNYC)
{
    Console.WriteLine($"{location.Name} is inside New York!");
}

Why is this cool?

• Contains() lets you check if a location is inside a polygon (city, park, etc.).
• This is super useful for geofencing, city-based filtering, and spatial searches.

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When Should You Use Spatial Data in EF Core?

Location-Based Apps – Track users, restaurants, stores, and landmarks.
Routing & Navigation – Calculate distances, find nearby places, optimize paths.
Geofencing – Detect when users enter or leave an area (e.g., delivery zones).
Real Estate & Mapping – Store city boundaries, zip codes, and regions.

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Wrap-Up: Bringing GIS Power to EF Core

Spatial data in EF Core isn’t just for maps—it’s for anything that involves locations, distances, and geographic relationships. By using NetTopologySuite and EF Core’s spatial capabilities, you can:

Store real-world locations with proper geospatial types
Run optimized queries for nearby locations and distances
Use polygons for geofencing, city boundaries, and more

If you’re building anything with location tracking, maps, or spatial analytics, EF Core has the built-in tools to make it easy!

Are you using spatial data in your projects? Let’s talk in the comments!