The The In this blog post, we will demonstrate how to implement support for the OData spatial EF Core enables mapping to spatial data types in the database by using Spatial types are supported in OData using the EF Core supports mapping to spatial data types using the In ASP.NET Core OData\u00a0 v8.0.5 we added ability to inject a custom implementation of the This tutorial assumes that you already have the knowledge to build an ASP.NET Core OData 8.x service. If not, start by reading Tutorial: Creating a Service with ASP.NET Core OData 8.0 for .NET 5<\/a>. Let\u2019s get started.<\/p>\n In this sample service, we will add capability to filter spatial data in AspNetCore OData 8<\/strong>, which is currently not supported.<\/p>\n We need to install 2 nuget packages:<\/p>\n Creating the Creating the database context.<\/p>\n We can then add a In If we run our service and try to get the Let’s modify the code in In the above changes, we are including the spatial properties in the model so that we can get the correct response.<\/p>\n If we re-run Let’s inspect the metadata: The The error above is occurring because To circumvent the issue described above, we will write custom wrappers to convert We make the following modifications to the The We are using the model builder to build the modified We are ignoring We are adding the Now if we inspect the service metadata, we will find the property OData types.<\/p>\n We can see the Let’s now filter against the We get an error<\/p>\n This means that We can customize the If we implement If we inherit from the Some of the methods we can override include:<\/p>\n In this example, we will inherit from the Note: In OData, a Let’s look at what each method in the above code does:<\/p>\n In If we re-run the filter query, we will get the correct results.<\/p>\n We have created an OData service that handles spatial data. We have customized the AspNetCore OData repo: https:\/\/github.com\/OData\/AspNetCoreOData<\/a><\/p>\nFilterBinder<\/code> translates an OData $filter<\/code> parse tree represented by a FilterClause<\/a> to an Expression<\/a>. The Expression<\/code> can be applied to an IQueryable<\/code> and passed to an ORM (e.g Entity Framework Core<\/a>) for processing.<\/p>\nFilterBinder<\/code> contains the default implementation on how the Expressions should be created. This creates a few issues:<\/p>\n\n
FilterBinder<\/code> may not be compatible with the target entity-relational mapper (O\/RM) framework.<\/li>\ngeo.distance<\/code> built-in function. The current ASP.NET Core OData 8 doesn’t support it.<\/p>\nNetTopologySuite<\/code> types in the model. These types are unknown to the IEdmModel<\/code>. We will be customizing our logic to work with both OData spatial<\/code> and NetTopologySuite<\/code> types.<\/p>\nOverview of spatial data types<\/h3>\n
Microsoft.Spatial<\/code> library. OData defines 8 spatial data types for geography<\/code> & geometry<\/code> respectively.<\/p>\nNetTopologySuite<\/code> spatial library.\nPreviously in EF classic, System.Data.Spatial<\/code> library was used.<\/p>\n![\"odata](\"https:\/\/devblogs.microsoft.com\/odata\/wp-content\/uploads\/sites\/23\/2022\/02\/spatial-types-updated.png\")
<\/a><\/p>\nBuilding the service<\/h3>\n
FilterBinder<\/code>.<\/p>\n\n
Model<\/h5>\n
Customer<\/code> entity model.<\/p>\npublic class Customer\r\n{\r\n\u00a0 \u00a0 public int Id { get; set; }\r\n\u00a0 \u00a0 public string Name { get; set; }\r\n\u00a0 \u00a0 public Point Loc { get; set; }\r\n}<\/pre>\nDatabase Context<\/h5>\n
public class CustomerContext : DbContext\r\n{\r\n public CustomerContext(DbContextOptions<CustomerContext> options)\r\n : base(options)\r\n {\r\n }\r\n\r\n public DbSet<Customer> Customers { get; set; }\r\n}<\/pre>\nData Source<\/h5>\n
DataSource.cs<\/code> file to prepopulate data whenever we run the service.<\/p>\npublic class DataSource\r\n{\r\n private static DataSource instance = new DataSource();\r\n public static DataSource Instance => instance;\r\n public List<Customer> Customers { get; set; }\r\n\r\n private DataSource()\r\n {\r\n this.Reset();\r\n this.Initialize();\r\n }\r\n public void Reset()\r\n {\r\n this.Customers = new List<Customer>();\r\n }\r\n\r\n public void Initialize()\r\n {\r\n Point seattle = new Point(-122.333056, 47.609722) { SRID = 4326 };\r\n Point redmond = new Point(-122.123889, 47.669444) { SRID = 4326 };\r\n\r\n this.Customers.AddRange(new List<Customer>()\r\n {\r\n new Customer()\r\n {\r\n Id = 1,\r\n Name = \"Customer 1\",\r\n Loc = seattle\r\n },\r\n new Customer()\r\n {\r\n Id = 2,\r\n Name = \"Customer 2\",\r\n Loc = redmond\r\n }\r\n });\r\n }\r\n}<\/pre>\nOther Configurations<\/h5>\n
Startup.cs<\/code>, we replace the ConfigureServices<\/code> method with the following code:<\/p>\npublic void ConfigureServices(IServiceCollection services)\r\n{\r\n services.AddDbContext<CustomerContext>(opt => opt.UseInMemoryDatabase(\"CustomerGeoContext\"));\r\n services.AddControllers().AddOData(opt => opt.Count().Filter().Expand().Select().OrderBy().SetMaxTop(5)\r\n .AddRouteComponents(\"odata\", GetEdmModel()));\r\n}\r\n\r\nprivate static IEdmModel GetEdmModel()\r\n{\r\n ODataConventionModelBuilder builder = new ODataConventionModelBuilder();\r\n builder.EntitySet<Customer>(\"Customers\");\r\n return builder.GetEdmModel();\r\n}<\/pre>\nCustomers<\/code> data, we get a truncated response.<\/p>\nGET ~\/odata\/Customers<\/pre>\n
{\r\n \"@odata.context\": \"http:\/\/localhost:5000\/odata\/$metadata#Customers\",\r\n \"value\": [\r\n {\r\n \"Id\": 1,\r\n \"Name\": \"Customer 1\"<\/pre>\nGetEdmModel<\/code> method as follows:<\/p>\n public static IEdmModel GetEdmModel()\r\n {\r\n var builder = new ODataModelBuilder();\r\n\r\n builder.EntitySet<Customer>(\"Customers\");\r\n var customer = builder.EntityType<Customer>();\r\n customer.Property(c => c.Id);\r\n customer.Property(c => c.Name);\r\n customer.ComplexProperty(c => c.Loc);\r\n customer.HasKey(c => c.Id);\r\n\r\n var point = builder.ComplexType<Point>();\r\n point.Property(p => p.X);\r\n point.Property(p => p.Y);\r\n point.Property(p => p.Z);\r\n point.Property(p => p.M);\r\n point.ComplexProperty(p => p.CoordinateSequence);\r\n point.Property(p => p.NumPoints);\r\n\r\n var coordinateSequence = builder.ComplexType<CoordinateSequence>();\r\n coordinateSequence.Property(c => c.Dimension);\r\n coordinateSequence.Property(c => c.Measures);\r\n coordinateSequence.Property(c => c.Spatial);\r\n coordinateSequence.Property(c => c.HasZ);\r\n coordinateSequence.Property(c => c.HasM);\r\n coordinateSequence.Property(c => c.ZOrdinateIndex);\r\n coordinateSequence.Property(c => c.MOrdinateIndex);\r\n coordinateSequence.Property(c => c.Count);\r\n\r\n return builder.GetEdmModel();\r\n }<\/pre>\nGET ~\/odata\/Customers<\/code>, we will get the correct response.<\/p>\n{\r\n \"@odata.context\": \"http:\/\/localhost:5000\/odata\/$metadata#Customers\",\r\n \"value\": [\r\n {\r\n \"Id\": 1,\r\n \"Name\": \"Customer 1\",\r\n \"Loc\": {\r\n \"X\": -122.333056,\r\n \"Y\": 47.609722,\r\n \"Z\": \"NaN\",\r\n \"M\": \"NaN\",\r\n \"NumPoints\": 1,\r\n \"CoordinateSequence\": {\r\n \"Dimension\": 2,\r\n \"Measures\": 0,\r\n \"Spatial\": 2,\r\n \"HasZ\": false,\r\n \"HasM\": false,\r\n \"ZOrdinateIndex\": -1,\r\n \"MOrdinateIndex\": -1,\r\n \"Count\": 1\r\n }\r\n }\r\n },\r\n {\r\n \"Id\": 2,\r\n \"Name\": \"Customer 2\",\r\n \"Loc\": {\r\n \"X\": -122.123889,\r\n \"Y\": 47.669444,\r\n \"Z\": \"NaN\",\r\n \"M\": \"NaN\",\r\n \"NumPoints\": 1,\r\n \"CoordinateSequence\": {\r\n \"Dimension\": 2,\r\n \"Measures\": 0,\r\n \"Spatial\": 2,\r\n \"HasZ\": false,\r\n \"HasM\": false,\r\n \"ZOrdinateIndex\": -1,\r\n \"MOrdinateIndex\": -1,\r\n \"Count\": 1\r\n }\r\n }\r\n }\r\n ]\r\n}<\/pre>\nGET ~\/odata\/$metadata<\/code><\/p>\n<?xml version=\"1.0\" encoding=\"utf-8\"?>\r\n<edmx:Edmx Version=\"4.0\" xmlns:edmx=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edmx\">\r\n <edmx:DataServices>\r\n <Schema Namespace=\"GeometryWebAPI.Models\" xmlns=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edm\">\r\n <EntityType Name=\"Customer\">\r\n <Key>\r\n <PropertyRef Name=\"Id\" \/>\r\n <\/Key>\r\n <Property Name=\"Id\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"Name\" Type=\"Edm.String\" \/>\r\n <Property Name=\"Loc\" Type=\"NetTopologySuite.Geometries.Point\" Nullable=\"false\" \/>\r\n <\/EntityType>\r\n <\/Schema>\r\n <Schema Namespace=\"NetTopologySuite.Geometries\" xmlns=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edm\">\r\n <ComplexType Name=\"Point\">\r\n <Property Name=\"X\" Type=\"Edm.Double\" Nullable=\"false\" \/>\r\n <Property Name=\"Y\" Type=\"Edm.Double\" Nullable=\"false\" \/>\r\n <Property Name=\"Z\" Type=\"Edm.Double\" Nullable=\"false\" \/>\r\n <Property Name=\"M\" Type=\"Edm.Double\" Nullable=\"false\" \/>\r\n <Property Name=\"CoordinateSequence\" Type=\"NetTopologySuite.Geometries.CoordinateSequence\" Nullable=\"false\" \/>\r\n <Property Name=\"NumPoints\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <\/ComplexType>\r\n <ComplexType Name=\"CoordinateSequence\">\r\n <Property Name=\"Dimension\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"Measures\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"Spatial\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"HasZ\" Type=\"Edm.Boolean\" Nullable=\"false\" \/>\r\n <Property Name=\"HasM\" Type=\"Edm.Boolean\" Nullable=\"false\" \/>\r\n <Property Name=\"ZOrdinateIndex\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"MOrdinateIndex\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"Count\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <\/ComplexType>\r\n <\/Schema>\r\n <Schema Namespace=\"Default\" xmlns=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edm\">\r\n <EntityContainer Name=\"Container\">\r\n <EntitySet Name=\"Customers\" EntityType=\"GeometryWebAPI.Models.Customer\" \/>\r\n <\/EntityContainer>\r\n <\/Schema>\r\n <\/edmx:DataServices>\r\n<\/edmx:Edmx><\/pre>\n
Loc<\/code> property has a type\u00a0NetTopologySuite.Geometries.Point<\/code>. This is not an OData type. If we filter against this property, an ODataException<\/code> will be thrown\u00a0since the Odata Uri Parser doesn’t understand this type.\u00a0<\/span><\/p>\n{\r\n \"error\": {\r\n \"code\": \"\",\r\n \"message\": \"The query specified in the URI is not valid. No function signature for the function with name 'geo.distance' matches the specified arguments. The function signatures considered are: geo.distance(Edm.GeographyPoint Nullable=true, Edm.GeographyPoint Nullable=true); geo.distance(Edm.GeometryPoint Nullable=true, Edm.GeometryPoint Nullable=true).\",\r\n \"details\": [],\r\n \"innererror\": {}\r\n }\r\n}<\/pre>\ngeo.distance<\/code> spatial function expects arguments of the type Edm.GeographyPoint<\/code> or Edm.GeometryPoint<\/code>. Instead we are passing arguments of the type NetTopologySuite.Geometries.Point<\/code>.<\/span><\/p>\nWrapping the Spatial Data types<\/h5>\n
NetTopologySuite<\/code> types to OData spatial types.<\/p>\n public class GeographyPointWrapper\r\n {\r\n private readonly Point _dbPoint;\r\n protected GeographyPointWrapper(Point point)\r\n {\r\n _dbPoint = point;\r\n }\r\n\r\n public static implicit operator GeographyPoint(GeographyPointWrapper wrapper)\r\n {\r\n return GeographyPointConverter.ConvertPointTo(wrapper._dbPoint);\r\n }\r\n\r\n public static implicit operator GeographyPointWrapper(GeographyPoint pt)\r\n {\r\n return new GeographyPointWrapper(GeographyPointConverter.ConvertFrom(pt));\r\n }\r\n\r\n public static implicit operator Point(GeographyPointWrapper wrapper)\r\n {\r\n return wrapper._dbPoint;\r\n }\r\n\r\n public static implicit operator GeographyPointWrapper(Point point)\r\n {\r\n return new GeographyPointWrapper(point);\r\n }\r\n }<\/pre>\n public class GeographyPointConverter\r\n {\r\n public static GeographyPoint ConvertPointTo(Point dbPoint)\r\n {\r\n Debug.Assert(dbPoint.GeometryType == \"Point\");\r\n double lat = dbPoint.X;\r\n double lon = dbPoint.Y;\r\n double? alt = dbPoint.Z;\r\n double? m = dbPoint.M;\r\n return GeographyPoint.Create(lat, lon, alt, m);\r\n }\r\n\r\n public static Point ConvertFrom(GeographyPoint geographyPoint)\r\n {\r\n return new Point(geographyPoint.Latitude, geographyPoint.Longitude, (double)geographyPoint.Z);\r\n }\r\n }<\/pre>\nModify the Edm Model<\/h5>\n
Customer<\/code> model so that we can apply the wrapper on the model properties.<\/p>\n public class Customer\r\n {\r\n private GeographyPointWrapper _ptWrapper;\r\n public int Id { get; set; }\r\n public string Name { get; set; }\r\n\r\n public Point Loc\r\n {\r\n get { return _ptWrapper; }\r\n set { _ptWrapper = value; }\r\n }\r\n\r\n [NotMapped]\r\n public GeographyPoint EdmLoc\r\n {\r\n get { return _ptWrapper; }\r\n set { _ptWrapper = value; }\r\n }\r\n }<\/pre>\n[NotMapped]<\/code> attribute ensures the EdmLoc<\/code> is not mapped to EFcore<\/code> since EFCore<\/code> doesn’t understand GeographyPoint<\/code> which is an OData type.<\/p>\nBuild the modified Edm Model<\/h5>\n
EdmModel<\/code>.<\/p>\nLoc<\/code> property which is of type Point<\/code> (a NetTopologySuite<\/code> type).<\/p>\nEdmLoc<\/code> property (which is of type Edm.GeographyPoint<\/code>) to the model and renaming it to Loc<\/code>.<\/p>\npublic static IEdmModel GetEdmModel()\r\n{\r\n var builder = new ODataModelBuilder();\r\n builder.EntitySet<Customer>(\"Customers\");\r\n\r\n var customerType = builder.EntityType<Customer>();\r\n customerType.HasKey(c => c.Id).Ignore(c => c.Loc);\r\n customerType.Property(c => c.Name);\r\n\r\n var customer = builder.StructuralTypes.First(t => t.ClrType == typeof(Customer));\r\n customer.AddProperty(typeof(Customer).GetProperty(\"EdmLoc\")).Name = \"Loc\";\r\n return builder.GetEdmModel();\r\n}<\/pre>\n GET ~\/odata\/$metadata<\/code><\/p>\n<?xml version=\"1.0\" encoding=\"utf-8\"?>\r\n<edmx:Edmx Version=\"4.0\" xmlns:edmx=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edmx\">\r\n <edmx:DataServices>\r\n <Schema Namespace=\"GeometryWebAPI.Models\" xmlns=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edm\">\r\n <EntityType Name=\"Customer\">\r\n <Key>\r\n <PropertyRef Name=\"Id\" \/>\r\n <\/Key>\r\n <Property Name=\"Id\" Type=\"Edm.Int32\" Nullable=\"false\" \/>\r\n <Property Name=\"Name\" Type=\"Edm.String\" \/>\r\n <Property Name=\"Loc\" Type=\"Edm.GeographyPoint\" \/>\r\n <\/EntityType>\r\n <\/Schema>\r\n <Schema Namespace=\"Default\" xmlns=\"http:\/\/docs.oasis-open.org\/odata\/ns\/edm\">\r\n <EntityContainer Name=\"Container\">\r\n <EntitySet Name=\"Customers\" EntityType=\"GeometryWebAPI.Models.Customer\" \/>\r\n <\/EntityContainer>\r\n <\/Schema>\r\n <\/edmx:DataServices>\r\n<\/edmx:Edmx><\/pre>\n
Loc<\/code> property now has an Edm.GeographyPoint<\/code> type.<\/p>\nLoc<\/code> property<\/p>\nGET odata\/Customers?$filter=geo.distance(Loc, geography'POINT(10 30)') gt 20<\/pre>\n
{\r\n \"error\": {\r\n \"code\": \"\",\r\n \"message\": \"The query specified in the URI is not valid. Unknown function 'geo.distance'.\",\r\n \"details\": [],\r\n \"innererror\": {\r\n \"message\": \"Unknown function 'geo.distance'.\",\r\n \"type\": \"System.NotImplementedException\",\r\n \"stacktrace\": \"...\"\r\n }\r\n }\r\n}<\/pre>\ngeo.distance<\/code> (a spatial function) is not supported in AspNetCore OData 8.<\/p>\nCustomizing FilterBinder<\/h3>\n
FilterBinder<\/code> in 2 ways<\/p>\n\n
IFilterBinder<\/code> interface.<\/li>\nFilterBinder<\/code> class.<\/li>\n<\/ul>\nIFilterBinder<\/code> interface, we will have to write all implementations of Bind<\/code> methods from scratch. This can be time consuming but offers the most flexibility.<\/p>\nFilterBinder<\/code> class, we can override the specific Bind<\/code> methods that we want to modify while re-using the existing implementations of Bind<\/code> methods.<\/p>\npublic override Expression BindCollectionNode(Microsoft.OData.UriParser.CollectionNode node, QueryBinderContext context)\r\n\r\npublic override Expression BindConstantNode(Microsoft.OData.UriParser.ConstantNode constantNode, QueryBinderContext context)\r\n\r\npublic override Expression BindCountNode(Microsoft.OData.UriParser.CountNode node, QueryBinderContext context)\r\n\r\npublic override Expression BindNavigationPropertyNode(Microsoft.OData.UriParser.QueryNode sourceNode, IEdmNavigationProperty navigationProperty, string propertyPath, QueryBinderContext context)\r\n\r\npublic override Expression Expression BindSingleValueNode(Microsoft.OData.UriParser.SingleValueNode node, QueryBinderContext context)<\/pre>\n
FilterBinder<\/code> class and override the BindSingleValueFunctionCallNode(SingleValueFunctionCallNode node, QueryBinderContext context)<\/code> method. This is the method that binds function calls. We will modify this method to support geo.distance<\/code> spatial function.<\/p>\nSingleValueFunctionCallNode<\/code> is a node that represents a function call that returns a single value.<\/span><\/p>\nCustomFilterBinder<\/h5>\n
public class CustomFilterBinder : FilterBinder\r\n {\r\n internal const string GeoDistanceFunctionName = \"geo.distance\";\r\n\r\n private static readonly MethodInfo distanceMethodDb = typeof(Geometry).GetMethod(\"Distance\");\r\n\r\n public override Expression BindSingleValueFunctionCallNode(SingleValueFunctionCallNode node, QueryBinderContext context)\r\n {\r\n switch (node.Name)\r\n {\r\n case GeoDistanceFunctionName:\r\n return BindGeoDistance(node, context);\r\n\r\n default:\r\n return base.BindSingleValueFunctionCallNode(node, context);\r\n }\r\n }\r\n\r\n public Expression BindGeoDistance(SingleValueFunctionCallNode node, QueryBinderContext context)\r\n {\r\n Expression[] arguments = BindArguments(node.Parameters, context);\r\n\r\n string propertyName = null;\r\n\r\n foreach(var queryNode in node.Parameters)\r\n {\r\n if(queryNode.GetType() == typeof(SingleValuePropertyAccessNode))\r\n {\r\n SingleValuePropertyAccessNode svpan = queryNode as SingleValuePropertyAccessNode;\r\n propertyName = svpan.Property.Name;\r\n }\r\n }\r\n\r\n GetPointExpressions(arguments, propertyName, out MemberExpression memberExpression, out ConstantExpression constantExpression);\r\n var ex = Expression.Call(memberExpression, distanceMethodDb, constantExpression);\r\n\r\n return ex;\r\n }\r\n\r\n private static void GetPointExpressions(Expression[] expressions, string propertyName, out MemberExpression memberExpression, out ConstantExpression constantExpression)\r\n {\r\n memberExpression = null;\r\n constantExpression = null;\r\n\r\n foreach (Expression expression in expressions)\r\n {\r\n var memberExpr = expression as MemberExpression;\r\n var constantExpr = memberExpr.Expression as ConstantExpression;\r\n\r\n if (constantExpr != null)\r\n {\r\n GeographyPoint point = GetGeographyPointFromConstantExpression(constantExpr);\r\n constantExpression = Expression.Constant(CreatePoint(point.Latitude, point.Longitude));\r\n }\r\n else\r\n {\r\n memberExpression = Expression.Property(memberExpr.Expression, propertyName);\r\n }\r\n }\r\n }\r\n\r\n private static GeographyPoint GetGeographyPointFromConstantExpression(ConstantExpression expression)\r\n {\r\n GeographyPoint point = null;\r\n if (expression != null)\r\n {\r\n PropertyInfo constantExpressionValuePropertyInfo = expression.Type.GetProperty(\"Property\");\r\n point = constantExpressionValuePropertyInfo.GetValue(expression.Value) as GeographyPoint;\r\n }\r\n\r\n return point;\r\n }\r\n\r\n private static Point CreatePoint(double latitude, double longitude)\r\n {\r\n \/\/ 4326 is most common coordinate system used by GPS\/Maps\r\n var geometryFactory = NtsGeometryServices.Instance.CreateGeometryFactory(srid: 4326);\r\n\r\n \/\/ see https:\/\/docs.microsoft.com\/en-us\/ef\/core\/modeling\/spatial\r\n \/\/ Longitude and Latitude\r\n var newLocation = geometryFactory.CreatePoint(new Coordinate(longitude, latitude));\r\n\r\n return newLocation;\r\n }\r\n }<\/pre>\n\n
BindSingleValueFunctionCallNode<\/code> – checks if a function name is geo.distance<\/code>. If true call BindGeoDistance<\/code>. If not call the base method to handle other function calls.<\/li>\nBindGeoDistance<\/code> – Creates an expression from the SingleValueFunctionCallNode<\/code>.<\/li>\nGetPointExpressions<\/code> – Transforms SingleValueFunctionCallNode<\/code> arguments’ expressions and outputs a MemberExpression<\/code> and a ConstantExpression<\/code>. This will be used to create a MethodCallExpression<\/code> in BindGeoDistance<\/code>. The Expressions from the BindArguments<\/code> method in BindGeoDistance<\/code> have OData spatial types. However EFCore only understand NetTopologySuite<\/code> types. So we recreate the expressions with NetTopologySuite types.<\/li>\nGetGeographyPointFromConstantExpression<\/code> – Extracts the GeographyPoint<\/code> property from the ConstantExpression<\/code>.<\/li>\nCreatePoint<\/code> – Create Point<\/code> value, which is a NetTopologySuite<\/code> type.<\/li>\n<\/ul>\nInject CustomFilterBinder into DI container<\/h5>\n
Startup.cs<\/code>, w<\/span>e inject the CustomFilterBinder<\/code> as a Singleton.<\/p>\npublic void ConfigureServices(IServiceCollection services)\r\n{\r\n services.AddControllers().AddOData(opt => opt.Count().Filter().Expand().Select().OrderBy().SetMaxTop(5)\r\n .AddRouteComponents(\"odata\", GetEdmModel(), svcs =>\r\n {\r\n svcs.AddSingleton<IFilterBinder, CustomFilterBinder>();\r\n }));\r\n}\r\n\r\n<\/pre>\n{\r\n \"@odata.context\": \"http:\/\/localhost:5000\/odata\/$metadata#Customers\",\r\n \"value\": [\r\n {\r\n \"Id\": 1,\r\n \"Name\": \"Customer 1\",\r\n \"Loc\": {\r\n \"type\": \"Point\",\r\n \"coordinates\": [\r\n 47.609722,\r\n -122.333056,\r\n \"NaN\",\r\n \"NaN\"\r\n ],\r\n \"crs\": {\r\n \"type\": \"name\",\r\n \"properties\": {\r\n \"name\": \"EPSG:4326\"\r\n }\r\n }\r\n }\r\n },\r\n {\r\n \"Id\": 2,\r\n \"Name\": \"Customer 2\",\r\n \"Loc\": {\r\n \"type\": \"Point\",\r\n \"coordinates\": [\r\n 47.669444,\r\n -122.123889,\r\n \"NaN\",\r\n \"NaN\"\r\n ],\r\n \"crs\": {\r\n \"type\": \"name\",\r\n \"properties\": {\r\n \"name\": \"EPSG:4326\"\r\n }\r\n }\r\n }\r\n }\r\n ]\r\n}<\/pre>\nFinal thoughts<\/h3>\n
FilterBinder<\/code> to allows us filter against geo.distance<\/code> which is an OData spatial function currently not supported by AspNetCore OData 8.<\/p>\n\n
Useful links<\/h5>\n