Added support for !ZOOM! token in GPKG provider. (#161)

provider/gpkg/gpkgProvider.go

@@ -75,12 +75,26 @@ func (p *GPKGProvider) Layers() ([]mvt.LayerInfo, error) {
 	return ls, nil
 }
 
-func replaceTokens(qtext string) string {
+func replaceTokens(qtext string) (ttext string, tokensPresent map[string]bool) {
 	// --- Convert tokens provided to SQL
 	// The BBOX token requires parameters ordered as [maxx, minx, maxy, miny] and checks for overlap.
-	// Until support for named parameters, we'll only support one BBOX token per query.
-	ttext := strings.Replace(qtext, "!BBOX!", "minx <= ? AND maxx >= ? AND miny <= ? AND maxy >= ?", 1)
-	return ttext
+	// 	Until support for named parameters, we'll only support one BBOX token per query.
+	// The ZOOM token requires two parameters, both filled with the current zoom level.
+	//	Until support for named parameters, the ZOOM token must follow the BBOX token.
+	ttext = string(qtext)
+	tokensPresent = make(map[string]bool)
+
+	if strings.Count(ttext, "!BBOX!") > 0 {
+		tokensPresent["BBOX"] = true
+		ttext = strings.Replace(qtext, "!BBOX!", "minx <= ? AND maxx >= ? AND miny <= ? AND maxy >= ?", 1)
+	}
+
+	if strings.Count(ttext, "!ZOOM!") > 0 {
+		tokensPresent["ZOOM"] = true
+		ttext = strings.Replace(ttext, "!ZOOM!", "min_zoom <= ? AND max_zoom >= ?", 1)
+	}
+
+	return ttext, tokensPresent
 }
 
 func layerFromQuery(ctx context.Context, pLayer *GPKGLayer, rows *sql.Rows, rowCount *int, dtags map[string]interface{}) (
@@ -165,8 +179,8 @@ func layerFromQuery(ctx context.Context, pLayer *GPKGLayer, rows *sql.Rows, rowC
 				} else {
 					log.Info("SRID already default (%v), no conversion necessary", DefaultSRID)
 				}
-			case "minx", "miny", "maxx", "maxy":
-				// Skip these columns used for bounding box filtering
+			case "minx", "miny", "maxx", "maxy", "min_zoom", "max_zoom":
+				// Skip these columns used for bounding box and zoom filtering
 				continue
 			default:
 				// Grab any non-nil, non-id, non-bounding box, & non-geometry column as a tag
@@ -249,6 +263,7 @@ func (p *GPKGProvider) MVTLayer(ctx context.Context, layerName string, tile tego
 	geomFieldname := p.layers[layerName].geomFieldname
 	idFieldname := p.layers[layerName].idFieldname
 
+	var tokensPresent map[string]bool
 	if p.layers[layerName].tablename != "" {
 		// If layer was specified via "tablename" in config, construct query.
 		geomTablename := p.layers[layerName].tablename
@@ -260,13 +275,18 @@ func (p *GPKGProvider) MVTLayer(ctx context.Context, layerName string, tile tego
 		}
 		qtext = fmt.Sprintf("%v FROM %v l JOIN %v si ON l.%v = si.id WHERE geom IS NOT NULL AND !BBOX!",
 			selectClause, geomTablename, rtreeTablename, idFieldname)
-		qtext = replaceTokens(qtext)
+		qtext, tokensPresent = replaceTokens(qtext)
 	} else {
 		// If layer was specified via "sql" in config, collect it.
 		qtext = p.layers[layerName].sql
+		qtext, tokensPresent = replaceTokens(qtext)
 	}
 
 	qparams := []interface{}{tileBBox[2], tileBBox[0], tileBBox[3], tileBBox[1]}
+	if tokensPresent["ZOOM"] {
+		// Add the zoom level, once for comparison to min, once for max.
+		qparams = append(qparams, tile.ZLevel(), tile.ZLevel())
+	}
 	log.Debug("qtext: %v\nqparams: %v\n", qtext, qparams)
 	rows, err := db.Query(qtext, qparams...)
 	if err != nil {
@@ -448,13 +468,19 @@ func NewProvider(config map[string]interface{}) (mvt.Provider, error) {
 			}
 		} else {
 			// --- Layer from custom sql
-			customSql := replaceTokens(layerConfig["sql"].(string))
+			customSqlTemplate := layerConfig["sql"].(string)
+			customSql, tokensPresent := replaceTokens(customSqlTemplate)
 
 			// Get geometry type & srid from geometry of first row.
 			qtext := fmt.Sprintf("SELECT geom FROM (%v) LIMIT 1;", customSql)
 			var geomData []byte
+			// Set bounds & zoom params to include all layers
 			// Bounds checks need params: maxx, minx, maxy, miny
 			qparams := []interface{}{float64(180.0), float64(-180.0), float64(85.0511), float64(-85.0511)}
+			if tokensPresent["ZOOM"] {
+				// min_zoom will always be less than 100, and max_zoom will always be greater than 0.
+				qparams = append(qparams, 100, 0)
+			}
 			log.Debug("qtext: %v, params: %v", qtext, qparams)
 			row := db.QueryRow(qtext, qparams...)
 			err = row.Scan(&geomData)
@@ -476,7 +502,7 @@ func NewProvider(config map[string]interface{}) (mvt.Provider, error) {
 
 			l = GPKGLayer{
 				name:          layerName,
-				sql:           customSql,
+				sql:           customSqlTemplate,
 				srid:          int(h.SRSId()),
 				geomType:      geom,
 				geomFieldname: "geom",

provider/gpkg/gpkgProvider_test.go

@@ -15,11 +15,14 @@ import (
 var filePath string
 var directory string
 var GPKGFilePath string
+var GPKGNaturalEarthFilePath string
 
 func init() {
 	_, filePath, _, _ = runtime.Caller(0)
 	directory, _ = filepath.Split(filePath)
 	GPKGFilePath = directory + "test_data/athens-osm-20170921.gpkg"
+	// This gpkg has zoom level information
+	GPKGNaturalEarthFilePath = directory + "test_data/natural_earth_minimal.gpkg"
 }
 
 func TestNewGPKGProvider(t *testing.T) {
@@ -44,14 +47,19 @@ func TestNewGPKGProvider(t *testing.T) {
 
 type MockTile struct {
 	tegola.TegolaTile
-	bbox [4]float64
+	bbox   [4]float64
+	zlevel int
 }
 
 func (tile *MockTile) BoundingBox() tegola.BoundingBox {
 	bb := tegola.BoundingBox{Minx: tile.bbox[0], Miny: tile.bbox[1], Maxx: tile.bbox[2], Maxy: tile.bbox[3]}
 	return bb
 }
 
+func (tile *MockTile) ZLevel() int {
+	return tile.zlevel
+}
+
 func TestMVTLayerFiltering(t *testing.T) {
 	layers := []map[string]interface{}{
 		{"name": "rl_lines", "tablename": "rail_lines"},
@@ -329,3 +337,72 @@ func TestConfigSQL(t *testing.T) {
 		}
 	}
 }
+
+func TestConfigZOOM(t *testing.T) {
+	// Checks the proper functioning of a "fields" config variable which specifies which
+	//	columns of a table should be converted to tags beyond the defaults.
+
+	// --- Get provider with sql specified for layers in config.
+	layers := []map[string]interface{}{
+		{"name": "land1",
+			"sql": "SELECT fid, geom, featurecla, min_zoom, 22 as max_zoom, minx, miny, maxx, maxy " +
+				"FROM ne_110m_land t JOIN rtree_ne_110m_land_geom si ON t.fid = si.id " +
+				"WHERE !BBOX! AND !ZOOM!",
+		},
+		{"name": "land2",
+			"sql": "SELECT fid, geom, featurecla, min_zoom, 22 as max_zoom, minx, miny, maxx, maxy " +
+				"FROM ne_110m_land t JOIN rtree_ne_110m_land_geom si ON t.fid = si.id " +
+				"WHERE !BBOX! AND !ZOOM!",
+		},
+	}
+
+	config := map[string]interface{}{
+		"FilePath": GPKGNaturalEarthFilePath,
+		"layers":   layers,
+	}
+	p, err := NewProvider(config)
+	if err != nil {
+		fmt.Printf("Error creating provider: %v\n", err)
+		t.FailNow()
+	}
+
+	// --- Check that features are populated
+	ctx := context.TODO()
+	// TODO: There's some confusion between pixel coordinates & WebMercator positions in the tile
+	//	bounding box, making the smallest y-value in pos #4 instead of pos #2
+	//	At some point, clean up this problem: https://github.com/terranodo/tegola/issues/189
+	pixelExtentEntireWorld := [4]float64{-20026376.39, 20048966.10, 20026376.39, -20048966.10}
+	mt := &MockTile{bbox: pixelExtentEntireWorld}
+	tags := make(map[string]interface{})
+
+	type TagLookupByFeatureId map[uint64]map[string]interface{}
+	type TestCase struct {
+		lName                string
+		zlevel               int
+		expectedFeatureCount int
+	}
+
+	testCases := []TestCase{
+		{
+			lName:                "land1",
+			zlevel:               1,
+			expectedFeatureCount: 101,
+		},
+		{
+			lName:                "land2",
+			zlevel:               0,
+			expectedFeatureCount: 44,
+		},
+	}
+
+	for i, tc := range testCases {
+		mt.zlevel = tc.zlevel
+		l, err := p.MVTLayer(ctx, tc.lName, mt, tags)
+		if err != nil {
+			t.Errorf("TestCase[%v]: Error in call to p.MVTLayer(%v): %v\n", i, tc.lName, err)
+		}
+
+		assert.Equal(t, tc.expectedFeatureCount, len(l.Features()))
+	}
+
+}

tile.go

@@ -15,6 +15,7 @@ type TegolaTile interface {
 	BoundingBox() BoundingBox
 	ZRes() float64
 	ZEpislon() float64
+	ZLevel() int
 }
 
 //Tile slippy map tilenames
@@ -68,6 +69,11 @@ func (t *Tile) BoundingBox() BoundingBox {
 	}
 }
 
+// Returns web mercator zoom level
+func (t *Tile) ZLevel() int {
+	return t.Z
+}
+
 //ZRes takes a web mercator zoom level and returns the pixel resolution for that
 //	scale, assuming 256x256 pixel tiles. Non-integer zoom levels are accepted.
 //	ported from: https://raw.githubusercontent.com/mapbox/postgis-vt-util/master/postgis-vt-util.sql