GeoJSON Schemes description for OpenAPI/Swagger in ASP.NET

GeoJSONSchemes.cs

using Microsoft.OpenApi.Any;
using Microsoft.OpenApi.Extensions;
using Microsoft.OpenApi.Interfaces;
using Microsoft.OpenApi.Models;
using NetTopologySuite.Features;
using NetTopologySuite.Geometries;
using Swashbuckle.AspNetCore.SwaggerGen;

namespace hello.Common;

public class GeoJSONSchemes
{
    class DocumentFilter : IDocumentFilter
    {
        public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
        {
            swaggerDoc.Components.Schemas.Add(
                "Point3D",
                new OpenApiSchema
                {
                    Type = "array",
                    Description = "Point in 3D space",
                    ExternalDocs = new OpenApiExternalDocs
                    {
                        Url = new Uri("http://geojson.org/geojson-spec.html#id2")
                    },
                    MinItems = 2,
                    MaxItems = 3,
                    Items = new OpenApiSchema
                    {
                        Type = "number"
                    }
                }
            );

            swaggerDoc.Components.Schemas.Add("Geometry",
                new OpenApiSchema
                {
                    ExternalDocs = new OpenApiExternalDocs
                    {
                        Url = new("http://geojson.org/geojson-spec.html#geometry-objects"),
                    },
                    Type = "object",
                    Extensions = new Dictionary<string, IOpenApiExtension>
                    {
                        ["clrType"] = new OpenApiString(typeof(Geometry).FullName)
                    },
                    Description = "GeoJSON geometry",
                    Discriminator = new OpenApiDiscriminator
                    {
                        PropertyName = "type",
                    },
                    Required = new HashSet<string> {"type"},
                    Properties = new Dictionary<string, OpenApiSchema>
                    {
                        ["type"] = new OpenApiSchema
                        {
                            Type = "string",
                            Enum = new List<IOpenApiAny>
                            {
                                new OpenApiString("Point"),
                                new OpenApiString("LineString"),
                                new OpenApiString("Polygon"),
                                new OpenApiString("MultiPoint"),
                                new OpenApiString("MultiLineString"),
                                new OpenApiString("MultiPolygon"),
                            },
                            Description = "the geometry type"
                        }
                    }
                }
            );
        }
    }

    public static void ConfigureForNetTopologySuite(SwaggerGenOptions c)
    {
        c.DocumentFilter<DocumentFilter>();
        c.MapType<Geometry>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#geometry-objects"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(Geometry).FullName)
                },
                Description = "GeoJSON geometry",
                Discriminator = new OpenApiDiscriminator
                {
                    PropertyName = "type",
                },
                Required = new HashSet<string> {"type"},
                Properties = new Dictionary<string, OpenApiSchema>
                {
                    ["type"] = new OpenApiSchema
                    {
                        Type = "string",
                        Enum = new List<IOpenApiAny>
                        {
                            new OpenApiString("Point"),
                            new OpenApiString("LineString"),
                            new OpenApiString("Polygon"),
                            new OpenApiString("MultiPoint"),
                            new OpenApiString("MultiLineString"),
                            new OpenApiString("MultiPolygon"),
                        },
                        Description = "the geometry type"
                    }
                }
            }
        );

        c.MapType<Point>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#id2"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(Point).FullName)
                },
                Description = "GeoJSON Point",
                AllOf = new List<OpenApiSchema>
                {
                    new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "Geometry",
                        }
                    },
                    new OpenApiSchema
                    {
                        Properties = new Dictionary<string, OpenApiSchema>
                        {
                            ["coordinates"] = new OpenApiSchema
                            {
                                Reference = new OpenApiReference
                                {
                                    Type = ReferenceType.Schema,
                                    Id = "Point3D"
                                }
                            }
                        }
                    }
                },
            }
        );
        c.MapType<LineString>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#id3"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(LineString).FullName)
                },
                Description = "GeoJSON LineString",
                AllOf = new List<OpenApiSchema>
                {
                    new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "Geometry",
                        }
                    },
                    new OpenApiSchema
                    {
                        Properties = new Dictionary<string, OpenApiSchema>
                        {
                            ["type"] = new OpenApiSchema()
                            {
                                Type = "string",
                                Enum = new List<IOpenApiAny>
                                {
                                    new OpenApiString("LineString"),
                                },
                            },
                            ["coordinates"] = new OpenApiSchema
                            {
                                Type = "array",
                                Items = new OpenApiSchema
                                {
                                    Reference = new OpenApiReference
                                    {
                                        Type = ReferenceType.Schema,
                                        Id = "Point3D"
                                    }
                                }
                            }
                        }
                    }
                },
            }
        );
        c.MapType<Polygon>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#id4"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(Polygon).FullName)
                },
                Description = "GeoJSON Polygon",
                AllOf = new List<OpenApiSchema>
                {
                    new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "Geometry",
                        }
                    },
                    new OpenApiSchema
                    {
                        Properties = new Dictionary<string, OpenApiSchema>
                        {
                            ["type"] = new OpenApiSchema()
                            {
                                Type = "string",
                                Enum = new List<IOpenApiAny>
                                {
                                    new OpenApiString("Polygon"),
                                },
                            },
                            ["coordinates"] = new OpenApiSchema
                            {
                                Type = "array",
                                Items = new OpenApiSchema
                                {
                                    Type = "array",
                                    Items = new OpenApiSchema
                                    {
                                        Reference = new OpenApiReference
                                        {
                                            Type = ReferenceType.Schema,
                                            Id = "Point3D"
                                        }
                                    }
                                }
                            }
                        }
                    }
                },
            }
        );
        c.MapType<MultiPoint>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#id4"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(MultiPoint).FullName)
                },
                Description = "GeoJSON MultiPolygon",
                AllOf = new List<OpenApiSchema>
                {
                    new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "Geometry",
                        }
                    },
                    new OpenApiSchema
                    {
                        Properties = new Dictionary<string, OpenApiSchema>
                        {
                            ["type"] = new OpenApiSchema()
                            {
                                Type = "string",
                                Enum = new List<IOpenApiAny>
                                {
                                    new OpenApiString("MultiPoint"),
                                },
                            },
                            ["coordinates"] = new OpenApiSchema
                            {
                                Type = "array",
                                Items = new OpenApiSchema
                                {
                                    Reference = new OpenApiReference
                                    {
                                        Type = ReferenceType.Schema,
                                        Id = "Point3D"
                                    }
                                }
                            }
                        }
                    }
                },
            }
        );
        c.MapType<MultiLineString>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#id5"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(MultiLineString).FullName)
                },
                Description = "GeoJSON MultiLineString",
                AllOf = new List<OpenApiSchema>
                {
                    new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "Geometry",
                        }
                    },
                    new OpenApiSchema
                    {
                        Properties = new Dictionary<string, OpenApiSchema>
                        {
                            ["type"] = new OpenApiSchema()
                            {
                                Type = "string",
                                Enum = new List<IOpenApiAny>
                                {
                                    new OpenApiString("MultiLineString"),
                                },
                            },
                            ["coordinates"] = new OpenApiSchema
                            {
                                Type = "array",
                                Items = new OpenApiSchema
                                {
                                    Type = "array",
                                    Items = new OpenApiSchema
                                    {
                                        Reference = new OpenApiReference
                                        {
                                            Type = ReferenceType.Schema,
                                            Id = "Point3D"
                                        }
                                    }
                                }
                            }
                        }
                    }
                },
            }
        );
        c.MapType<MultiPolygon>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#id6"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(MultiPolygon).FullName)
                },
                Description = "GeoJSON MultiPolygon",
                AllOf = new List<OpenApiSchema>
                {
                    new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "Geometry",
                        }
                    },
                    new OpenApiSchema
                    {
                        Properties = new Dictionary<string, OpenApiSchema>
                        {
                            ["type"] = new OpenApiSchema()
                            {
                                Type = "string",
                                Enum = new List<IOpenApiAny>
                                {
                                    new OpenApiString("MultiPolygon"),
                                },
                            },
                            ["coordinates"] = new OpenApiSchema
                            {
                                Type = "array",
                                Items = new OpenApiSchema
                                {
                                    Type = "array",
                                    Items = new OpenApiSchema
                                    {
                                        Type = "array",
                                        Items = new OpenApiSchema
                                        {
                                            Reference = new OpenApiReference
                                            {
                                                Type = ReferenceType.Schema,
                                                Id = "Point3D"
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                },
            }
        );
        c.MapType<GeometryCollection>(
            () => new OpenApiSchema
            {
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("http://geojson.org/geojson-spec.html#geometrycollection"),
                },
                Type = "object",
                Extensions = new Dictionary<string, IOpenApiExtension>
                {
                    ["clrType"] = new OpenApiString(typeof(GeometryCollection).FullName)
                },
                Required = new HashSet<string> {"type", "geometries"},
                Description = "GeoJSON geometry collection",
                Properties = new Dictionary<string, OpenApiSchema>
                {
                    ["type"] = new OpenApiSchema
                    {
                        Type = "string",
                        Enum = new List<IOpenApiAny> {new OpenApiString("GeometryCollection")},
                    },
                    ["geometries"] = new OpenApiSchema
                    {
                        Type = "array",
                        Items = new OpenApiSchema
                        {
                            Reference = new OpenApiReference
                            {
                                Type = ReferenceType.Schema,
                                Id = "Geometry"
                            }
                        }
                    }
                }
            }
        );

        c.MapType<Feature>(
            () => new OpenApiSchema
            {
                Type = "object",
                Description = "GeoJSON Feature",
                Required = new HashSet<string> {"type", "id", "geometry"},
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("https://tools.ietf.org/html/rfc7946#section-3.2")
                },
                Properties = new Dictionary<string, OpenApiSchema>
                {
                    ["type"] = new OpenApiSchema
                    {
                        Type = "string",
                        Enum = new List<IOpenApiAny> {new OpenApiString("Feature")}
                    },
                    ["id"] = new OpenApiSchema
                    {
                        Type = "integer",
                    },
                    ["geometry"] = new OpenApiSchema
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.Schema,
                            Id = "GeometryCollection",
                        }
                    },
                    ["properties"] = new OpenApiSchema
                    {
                        Type = "object"
                    }
                }
            }
        );

        c.MapType<FeatureCollection>(
            () => new OpenApiSchema
            {
                Type = "object",
                Description = "GeoJSON Feature collection",
                Required = new HashSet<string> {"type", "features"},
                ExternalDocs = new OpenApiExternalDocs
                {
                    Url = new("https://tools.ietf.org/html/rfc7946#section-3.2")
                },
                Properties = new Dictionary<string, OpenApiSchema>
                {
                    ["type"] = new OpenApiSchema
                    {
                        Type = "string",
                        Enum = new List<IOpenApiAny> {new OpenApiString("FeatureCollection")}
                    },
                    ["features"] = new OpenApiSchema
                    {
                        Type = "array",
                        Items = new OpenApiSchema
                        {
                            Reference = new OpenApiReference
                            {
                                Type = ReferenceType.Schema,
                                Id = "Feature"
                            }
                        }
                    }
                }
            }
        );
    }
}

Program.cs

//ADD option
builder.Services.AddSwaggerGen(GeoJSONSchemes.ConfigureForNetTopologySuite);