feat: cache geojson data for vector files

internal/domain/dataset.go

@@ -217,6 +217,11 @@ type Dataset struct {
 	// Geometry is the dataset's spatial geometry, serialized as GeoJSON.
 	// Nullable; populated from the file's spatial data.
 	Geometry json.RawMessage `json:"geometry"`
+	// GeoJSON is the pre-assembled GeoJSON FeatureCollection served by the
+	// .geojson endpoint. It is generated and persisted at processing time for
+	// vector and vector_with_kato datasets. Nullable; not exposed on the dataset
+	// response (served only by the .geojson endpoint).
+	GeoJSON json.RawMessage `json:"-"`
 	// BBox is the axis-aligned bounding box [minX, minY, maxX, maxY] derived
 	// from the geometry. Included in responses only for raster datasets.
 	BBox      []float64 `json:"bbox,omitempty"`

internal/repository/postgres/dataset.go

@@ -31,6 +31,7 @@ const datasetColumns = `id, category_id, name, description, unit, filename, stor
 	CASE WHEN file_type = 'raster' AND geometry IS NOT NULL
 	     THEN ARRAY[ST_XMin(geometry), ST_YMin(geometry), ST_XMax(geometry), ST_YMax(geometry)]
 	     ELSE NULL END AS bbox,
+	geojson,
 	created_at, updated_at`
 
 func scanDataset(row pgx.Row) (domain.Dataset, error) {
@@ -40,7 +41,7 @@ func scanDataset(row pgx.Row) (domain.Dataset, error) {
 		&d.Filename, &d.StorageKey, &d.CogStorageKey, &d.FileType, &d.SizeBytes, &d.ContentType,
 		&d.Properties, &d.Meta, &d.Automated, &d.Status,
 		&d.AttributeColumns, &d.KatoColumn, &d.YearColumns, &d.ParseError,
-		&d.Geometry, &d.BBox, &d.CreatedAt, &d.UpdatedAt,
+		&d.Geometry, &d.BBox, &d.GeoJSON, &d.CreatedAt, &d.UpdatedAt,
 	)
 	return d, err
 }
@@ -193,6 +194,23 @@ func (r *DatasetRepository) MarkReady(ctx context.Context, id uuid.UUID, geometr
 	return nil
 }
 
+// SetGeoJSON stores the pre-assembled GeoJSON FeatureCollection for a dataset
+// (nil -> NULL). It is written at processing time and served verbatim by the
+// .geojson endpoint.
+func (r *DatasetRepository) SetGeoJSON(ctx context.Context, id uuid.UUID, geojson []byte) error {
+	tag, err := r.pool.Exec(ctx,
+		`UPDATE datasets SET geojson = $2, updated_at = now() WHERE id = $1`,
+		id, nullableJSON(json.RawMessage(geojson)),
+	)
+	if err != nil {
+		return mapError(err)
+	}
+	if tag.RowsAffected() == 0 {
+		return domain.ErrNotFound
+	}
+	return nil
+}
+
 // ReplaceObservations atomically replaces all observations for a dataset.
 func (r *DatasetRepository) ReplaceObservations(ctx context.Context, datasetID uuid.UUID, obs []domain.Observation) error {
 	tx, err := r.pool.Begin(ctx)

internal/service/dataset.go

@@ -34,6 +34,7 @@ type DatasetRepository interface {
 	MarkReady(ctx context.Context, id uuid.UUID, geometry []byte) error
 	MarkConverted(ctx context.Context, id uuid.UUID, cogKey string, footprint []byte) error
 	SetProperties(ctx context.Context, id uuid.UUID, properties, geometry []byte) error
+	SetGeoJSON(ctx context.Context, id uuid.UUID, geojson []byte) error
 	SaveMapping(ctx context.Context, id uuid.UUID, katoColumn string, years []domain.YearColumn) (domain.Dataset, error)
 	ReplaceObservations(ctx context.Context, datasetID uuid.UUID, obs []domain.Observation) error
 	ListObservations(ctx context.Context, datasetID uuid.UUID, katoCode *string, limit, offset int) ([]domain.Observation, error)
@@ -317,7 +318,12 @@ func (s *DatasetService) ExtractProperties(ctx context.Context, id uuid.UUID) er
 	}
 
 	geometry := s.vectorGeometry(ctx, dataset.Filename, data)
-	return s.repo.SetProperties(ctx, id, properties, geometry)
+	if err := s.repo.SetProperties(ctx, id, properties, geometry); err != nil {
+		return err
+	}
+	// Assemble and persist the GeoJSON served by the .geojson endpoint from the
+	// now-canonical (unioned) geometry and attribute table.
+	return s.generateGeoJSON(ctx, id)
 }
 
 // vectorGeometry dissolves a vector file's features into a single GeoJSON
@@ -558,7 +564,12 @@ func (s *DatasetService) Extract(ctx context.Context, id uuid.UUID) error {
 	}
 
 	geometry := s.vectorGeometry(ctx, dataset.Filename, data)
-	return s.repo.MarkReady(ctx, id, geometry)
+	if err := s.repo.MarkReady(ctx, id, geometry); err != nil {
+		return err
+	}
+	// Assemble and persist the GeoJSON served by the .geojson endpoint by joining
+	// the districts table on the freshly extracted observations.
+	return s.generateGeoJSON(ctx, id)
 }
 
 // buildObservations unpivots rows into observations. Rows without a KATO code
@@ -629,33 +640,82 @@ func (s *DatasetService) ListObservations(ctx context.Context, id uuid.UUID, kat
 	return ObservationPage{Items: items, Page: page, PageSize: pageSize, Total: total}, nil
 }
 
-// GeoJSON assembles a GeoJSON FeatureCollection (RFC 7946) for a vector or
-// vector_with_kato dataset.
+// emptyFeatureCollectionJSON is served when a dataset has no persisted GeoJSON
+// (e.g. it carried no geometry), so the endpoint always returns a valid RFC 7946
+// FeatureCollection.
+var emptyFeatureCollectionJSON = json.RawMessage(`{"type":"FeatureCollection","features":[]}`)
+
+// GeoJSON returns the pre-assembled GeoJSON FeatureCollection (RFC 7946) stored
+// for a vector or vector_with_kato dataset. The collection is normally generated
+// and persisted at processing time (see generateGeoJSON), and this method serves
+// the stored column verbatim.
 //
-// A plain vector dataset has no KATO mapping or observations, so the result is a
-// single geometry-only Feature wrapping the dataset's own (dissolved) geometry,
-// with empty properties (or an empty collection when the dataset has no
-// geometry).
+// For backward compatibility with datasets that became ready before the column
+// existed, an empty column is assembled on demand, persisted (so subsequent
+// requests are served from the cached column), and returned.
+//
+// Only ready datasets are served; a dataset still being processed yields a
+// conflict, and unsupported file types (e.g. raster) yield a validation error.
+func (s *DatasetService) GeoJSON(ctx context.Context, id uuid.UUID) (json.RawMessage, error) {
+	dataset, err := s.loadGeoJSONDataset(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	if len(dataset.GeoJSON) > 0 {
+		return dataset.GeoJSON, nil
+	}
+
+	// Empty column (ready dataset processed before GeoJSON was persisted at
+	// processing time): assemble it now, cache it, and return it.
+	raw, err := s.buildGeoJSON(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	if len(raw) == 0 {
+		raw = emptyFeatureCollectionJSON
+	}
+	if err := s.repo.SetGeoJSON(ctx, id, raw); err != nil {
+		return nil, err
+	}
+	return raw, nil
+}
+
+// generateGeoJSON assembles the dataset's GeoJSON FeatureCollection and persists
+// it. It is invoked at processing time for vector and vector_with_kato datasets;
+// rasters (and any other type) store nothing.
+func (s *DatasetService) generateGeoJSON(ctx context.Context, id uuid.UUID) error {
+	raw, err := s.buildGeoJSON(ctx, id)
+	if err != nil {
+		return err
+	}
+	return s.repo.SetGeoJSON(ctx, id, raw)
+}
+
+// buildGeoJSON assembles a GeoJSON FeatureCollection (RFC 7946) for a dataset
+// from its persisted state, returning the marshaled bytes (nil for unsupported
+// file types).
+//
+// A plain vector dataset yields a single geometry-only Feature wrapping the
+// dataset's own (dissolved) geometry, exposing its extracted attribute table as
+// the Feature's properties (or an empty collection when it has no geometry).
 //
 // A vector_with_kato dataset always ignores any geometry it carries and instead
 // joins the districts table on KATO code: one Feature is emitted per KATO, its
 // boundary taken from the districts table and its observation values nested
 // under a `data` object (keyed by date) alongside `kato` and `name`. KATO codes
 // with no matching district are skipped.
-//
-// Only ready datasets are served; a dataset still being processed yields a
-// conflict.
-func (s *DatasetService) GeoJSON(ctx context.Context, id uuid.UUID) (domain.FeatureCollection, error) {
-	dataset, err := s.loadGeoJSONDataset(ctx, id)
+func (s *DatasetService) buildGeoJSON(ctx context.Context, id uuid.UUID) (json.RawMessage, error) {
+	dataset, err := s.repo.GetByID(ctx, id)
 	if err != nil {
-		return domain.FeatureCollection{}, err
+		return nil, err
 	}
 
-	// Plain vector: no KATO mapping or observations. Return the dataset's own
-	// geometry as a single Feature, exposing the extracted attribute table (e.g.
-	// a GeoPackage's table data) as the Feature's top-level properties.
-	if dataset.FileType == domain.FileTypeVector {
-		fc := domain.FeatureCollection{Type: domain.GeoJSONFeatureCollection, Features: []domain.Feature{}}
+	var fc domain.FeatureCollection
+	switch dataset.FileType {
+	case domain.FileTypeVector:
+		// Plain vector: the dataset's own geometry as a single Feature, exposing the
+		// extracted attribute table (e.g. a GeoPackage's table data) as properties.
+		fc = domain.FeatureCollection{Type: domain.GeoJSONFeatureCollection, Features: []domain.Feature{}}
 		if hasGeometry(dataset.Geometry) {
 			fc.Features = append(fc.Features, domain.Feature{
 				Type:       domain.GeoJSONFeature,
@@ -663,21 +723,24 @@ func (s *DatasetService) GeoJSON(ctx context.Context, id uuid.UUID) (domain.Feat
 				Properties: vectorFeatureProperties(dataset.Properties),
 			})
 		}
-		return fc, nil
+	case domain.FileTypeVectorWithKato:
+		// Always ignore the dataset's own geometry; build one Feature per KATO from
+		// the districts table.
+		obs, err := s.repo.ListAllObservations(ctx, id)
+		if err != nil {
+			return nil, err
+		}
+		grouped, order := groupObservationsByKato(obs)
+		features, err := s.districtFeatures(ctx, grouped, order)
+		if err != nil {
+			return nil, err
+		}
+		fc = domain.FeatureCollection{Type: domain.GeoJSONFeatureCollection, Features: features}
+	default:
+		return nil, nil // rasters carry no GeoJSON
 	}
 
-	// vector_with_kato: always ignore the dataset's own geometry and build one
-	// Feature per KATO from the districts table.
-	obs, err := s.repo.ListAllObservations(ctx, id)
-	if err != nil {
-		return domain.FeatureCollection{}, err
-	}
-	grouped, order := groupObservationsByKato(obs)
-	features, err := s.districtFeatures(ctx, grouped, order)
-	if err != nil {
-		return domain.FeatureCollection{}, err
-	}
-	return domain.FeatureCollection{Type: domain.GeoJSONFeatureCollection, Features: features}, nil
+	return json.Marshal(fc)
 }
 
 // loadGeoJSONDataset fetches a dataset for the GeoJSON endpoint and validates

internal/service/dataset_test.go

@@ -146,6 +146,16 @@ func (r *stubDatasetRepo) SetProperties(_ context.Context, id uuid.UUID, propert
 	return nil
 }
 
+func (r *stubDatasetRepo) SetGeoJSON(_ context.Context, id uuid.UUID, geojson []byte) error {
+	d, ok := r.store[id]
+	if !ok {
+		return domain.ErrNotFound
+	}
+	d.GeoJSON = geojson
+	r.store[id] = d
+	return nil
+}
+
 func (r *stubDatasetRepo) ReplaceObservations(_ context.Context, id uuid.UUID, obs []domain.Observation) error {
 	r.observations[id] = obs
 	return nil
@@ -784,6 +794,10 @@ func TestDatasetService_Extract(t *testing.T) {
 		KatoColumn:  &kato,
 		YearColumns: []domain.YearColumn{{Column: "F_2023", Date: "2023-01-01"}},
 	}
+	repo.districts["751010000"] = domain.District{
+		Kato: "751010000", Name: "Almaty",
+		Geometry: json.RawMessage(`{"type":"Polygon","coordinates":[[[76,43],[77,43],[77,44],[76,43]]]}`),
+	}
 	rows := []map[string]string{{"като": "751010000", "F_2023": "100"}}
 	rp := RowParser(func(string, []byte) ([]map[string]string, error) { return rows, nil })
 	geom := []byte(`{"type":"GeometryCollection","geometries":[]}`)
@@ -803,10 +817,36 @@ func TestDatasetService_Extract(t *testing.T) {
 	if len(got) != 1 || got[0].KatoCode != "751010000" || got[0].Value == nil || *got[0].Value != 100 {
 		t.Fatalf("unexpected observations: %+v", got)
 	}
+	// Extraction also assembles and persists the GeoJSON (district-joined).
+	var fc domain.FeatureCollection
+	if err := json.Unmarshal(repo.store[id].GeoJSON, &fc); err != nil {
+		t.Fatalf("geojson not persisted / invalid: %v", err)
+	}
+	if len(fc.Features) != 1 || fc.Features[0].Properties["name"] != "Almaty" {
+		t.Fatalf("unexpected persisted geojson: %s", repo.store[id].GeoJSON)
+	}
+}
+
+// mustGeoJSON generates and persists the dataset's GeoJSON (as the worker does),
+// then reads it back through the .geojson accessor and decodes it into a
+// FeatureCollection so tests can assert on its content.
+func mustGeoJSON(t *testing.T, svc *DatasetService, id uuid.UUID) domain.FeatureCollection {
+	t.Helper()
+	if err := svc.generateGeoJSON(context.Background(), id); err != nil {
+		t.Fatalf("generateGeoJSON: %v", err)
+	}
+	raw, err := svc.GeoJSON(context.Background(), id)
+	if err != nil {
+		t.Fatalf("GeoJSON: %v", err)
+	}
+	var fc domain.FeatureCollection
+	if err := json.Unmarshal(raw, &fc); err != nil {
+		t.Fatalf("decode geojson: %v", err)
+	}
+	return fc
 }
 
 func TestDatasetService_GeoJSON_DistrictJoin(t *testing.T) {
-	ctx := context.Background()
 	id := uuid.New()
 	repo := newStubDatasetRepo()
 	repo.store[id] = domain.Dataset{ID: id, FileType: domain.FileTypeVectorWithKato, Status: domain.DatasetStatusReady}
@@ -823,10 +863,7 @@ func TestDatasetService_GeoJSON_DistrictJoin(t *testing.T) {
 	}
 
 	svc := newDatasetService(repo, &stubStore{}, true)
-	fc, err := svc.GeoJSON(ctx, id)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
+	fc := mustGeoJSON(t, svc, id)
 	if fc.Type != domain.GeoJSONFeatureCollection {
 		t.Fatalf("type = %q", fc.Type)
 	}
@@ -858,7 +895,6 @@ func TestDatasetService_GeoJSON_DistrictJoin(t *testing.T) {
 }
 
 func TestDatasetService_GeoJSON_IgnoresDatasetGeometry(t *testing.T) {
-	ctx := context.Background()
 	id := uuid.New()
 	repo := newStubDatasetRepo()
 	// Dataset HAS its own geometry, which GeoJSON must ignore entirely for a
@@ -876,10 +912,7 @@ func TestDatasetService_GeoJSON_IgnoresDatasetGeometry(t *testing.T) {
 	repo.districts["710000000"] = domain.District{Kato: "710000000", Name: "Astana", Geometry: district}
 
 	svc := newDatasetService(repo, &stubStore{}, true)
-	fc, err := svc.GeoJSON(ctx, id)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
+	fc := mustGeoJSON(t, svc, id)
 	if len(fc.Features) != 1 {
 		t.Fatalf("want 1 feature (unmatched KATO skipped), got %d", len(fc.Features))
 	}
@@ -902,6 +935,58 @@ func TestDatasetService_GeoJSON_IgnoresDatasetGeometry(t *testing.T) {
 	}
 }
 
+func TestDatasetService_GeoJSON_ReturnsStoredColumn(t *testing.T) {
+	id := uuid.New()
+	repo := newStubDatasetRepo()
+	stored := json.RawMessage(`{"type":"FeatureCollection","features":[{"type":"Feature","geometry":null,"properties":{"kato":"710000000"}}]}`)
+	repo.store[id] = domain.Dataset{
+		ID: id, FileType: domain.FileTypeVectorWithKato, Status: domain.DatasetStatusReady,
+		GeoJSON: stored,
+	}
+	// Observations/districts are intentionally left empty: GeoJSON must serve the
+	// persisted column verbatim without re-assembling anything.
+	svc := newDatasetService(repo, &stubStore{}, true)
+
+	raw, err := svc.GeoJSON(context.Background(), id)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(raw) != string(stored) {
+		t.Fatalf("want stored column verbatim, got %s", raw)
+	}
+}
+
+func TestDatasetService_GeoJSON_LazilyGeneratesAndCaches(t *testing.T) {
+	// A dataset that became ready before the geojson column existed: the first
+	// request assembles it, persists it, and serves it from the cache thereafter.
+	id := uuid.New()
+	repo := newStubDatasetRepo()
+	repo.store[id] = domain.Dataset{ID: id, FileType: domain.FileTypeVectorWithKato, Status: domain.DatasetStatusReady}
+	v := 100.0
+	repo.observations[id] = []domain.Observation{{KatoCode: "710000000", Date: "2020-01-01", Value: &v}}
+	repo.districts["710000000"] = domain.District{
+		Kato: "710000000", Name: "Astana",
+		Geometry: json.RawMessage(`{"type":"Polygon","coordinates":[[[71,51],[72,51],[72,52],[71,51]]]}`),
+	}
+	svc := newDatasetService(repo, &stubStore{}, true)
+
+	raw, err := svc.GeoJSON(context.Background(), id)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	var fc domain.FeatureCollection
+	if err := json.Unmarshal(raw, &fc); err != nil {
+		t.Fatalf("decode geojson: %v", err)
+	}
+	if len(fc.Features) != 1 || fc.Features[0].Properties["name"] != "Astana" {
+		t.Fatalf("lazy-assembled geojson wrong: %s", raw)
+	}
+	// It must be cached on the dataset so subsequent requests skip re-assembly.
+	if string(repo.store[id].GeoJSON) != string(raw) {
+		t.Fatalf("geojson not cached after first request: %s", repo.store[id].GeoJSON)
+	}
+}
+
 func TestDatasetService_GeoJSON_ConflictWhenNotReady(t *testing.T) {
 	id := uuid.New()
 	repo := newStubDatasetRepo()
@@ -934,10 +1019,7 @@ func TestDatasetService_GeoJSON_Vector_GeometryOnly(t *testing.T) {
 	}
 	svc := newDatasetService(repo, &stubStore{}, true)
 
-	fc, err := svc.GeoJSON(context.Background(), id)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
+	fc := mustGeoJSON(t, svc, id)
 	if len(fc.Features) != 1 {
 		t.Fatalf("want a single geometry-only feature, got %d", len(fc.Features))
 	}
@@ -948,9 +1030,6 @@ func TestDatasetService_GeoJSON_Vector_GeometryOnly(t *testing.T) {
 	if len(f.Properties) != 0 {
 		t.Fatalf("vector feature should have empty properties, got %+v", f.Properties)
 	}
-	if _, err := json.Marshal(fc); err != nil {
-		t.Fatalf("feature collection not valid JSON: %v", err)
-	}
 }
 
 func TestDatasetService_GeoJSON_Vector_TableDataAsProperties(t *testing.T) {
@@ -964,10 +1043,7 @@ func TestDatasetService_GeoJSON_Vector_TableDataAsProperties(t *testing.T) {
 	}
 	svc := newDatasetService(repo, &stubStore{}, true)
 
-	fc, err := svc.GeoJSON(context.Background(), id)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
+	fc := mustGeoJSON(t, svc, id)
 	if len(fc.Features) != 1 {
 		t.Fatalf("want 1 feature, got %d", len(fc.Features))
 	}
@@ -988,11 +1064,10 @@ func TestDatasetService_GeoJSON_Vector_MultiRowTableData(t *testing.T) {
 	}
 	svc := newDatasetService(repo, &stubStore{}, true)
 
-	fc, err := svc.GeoJSON(context.Background(), id)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
-	rows, ok := fc.Features[0].Properties["rows"].([]map[string]any)
+	fc := mustGeoJSON(t, svc, id)
+	// After the JSON round trip through the stored column, the nested rows decode
+	// into a generic []any of objects.
+	rows, ok := fc.Features[0].Properties["rows"].([]any)
 	if !ok || len(rows) != 2 {
 		t.Fatalf("multi-row table data not kept under \"rows\": %+v", fc.Features[0].Properties)
 	}
@@ -1004,10 +1079,7 @@ func TestDatasetService_GeoJSON_Vector_NoGeometry(t *testing.T) {
 	repo.store[id] = domain.Dataset{ID: id, FileType: domain.FileTypeVector, Status: domain.DatasetStatusReady}
 	svc := newDatasetService(repo, &stubStore{}, true)
 
-	fc, err := svc.GeoJSON(context.Background(), id)
-	if err != nil {
-		t.Fatalf("unexpected error: %v", err)
-	}
+	fc := mustGeoJSON(t, svc, id)
 	if fc.Type != domain.GeoJSONFeatureCollection {
 		t.Fatalf("type = %q", fc.Type)
 	}

internal/transport/http/dataset_handler.go

@@ -304,11 +304,11 @@ func (h *DatasetHandler) get(w http.ResponseWriter, r *http.Request) {
 	httputil.WriteJSON(w, http.StatusOK, dataset)
 }
 
-// geojson returns the dataset as a GeoJSON FeatureCollection (RFC 7946). A
-// vector_with_kato dataset always ignores its own geometry and instead joins the
-// districts table on KATO code: one feature per KATO with the observation values
-// mapped onto its district polygon. A plain vector dataset serves its own
-// geometry as a single feature.
+// geojson returns the dataset's pre-assembled GeoJSON FeatureCollection (RFC
+// 7946), generated and stored at processing time. A vector_with_kato dataset's
+// collection joins the districts table on KATO code (one feature per KATO with
+// the observation values mapped onto its district polygon); a plain vector
+// dataset's collection wraps its own geometry as a single feature.
 func (h *DatasetHandler) geojson(w http.ResponseWriter, r *http.Request) {
 	id, ok := parseUUIDParam(w, r, "id")
 	if !ok {
@@ -321,7 +321,7 @@ func (h *DatasetHandler) geojson(w http.ResponseWriter, r *http.Request) {
 	}
 	w.Header().Set("Content-Type", "application/geo+json")
 	w.WriteHeader(http.StatusOK)
-	_ = json.NewEncoder(w).Encode(fc)
+	_, _ = w.Write(fc)
 }
 
 func (h *DatasetHandler) download(w http.ResponseWriter, r *http.Request) {

migrations/00007_add_geojson_to_datasets.sql

@@ -0,0 +1,8 @@
+-- +goose Up
+-- Pre-assembled GeoJSON FeatureCollection served by the /datasets/{id}.geojson
+-- endpoint. Generated at processing time for vector and vector_with_kato
+-- datasets (NULL until generated / for rasters).
+ALTER TABLE datasets ADD COLUMN geojson JSONB;
+
+-- +goose Down
+ALTER TABLE datasets DROP COLUMN geojson;