Support for importing non-area relations as MultiLineString

Author: talaj

database/postgis/postgis.go

@@ -72,8 +72,8 @@ func addGeometryColumn(tx *sql.Tx, tableName string, spec TableSpec) error {
 	}
 
 	geomType := strings.ToUpper(spec.GeometryType)
-	if geomType == "POLYGON" {
-		geomType = "GEOMETRY" // for multipolygon support
+	if geomType == "POLYGON" || geomType == "LINESTRING" {
+		geomType = "GEOMETRY" // for multigeometry support
 	}
 	sql := fmt.Sprintf("SELECT AddGeometryColumn('%s', '%s', '%s', '%d', '%s', 2);",
 		spec.Schema, tableName, colName, spec.Srid, geomType)

geom/multilinestring.go

@@ -0,0 +1,43 @@
+package geom
+
+import (
+	"github.com/omniscale/imposm3/element"
+	"github.com/omniscale/imposm3/geom/geos"
+	"errors"
+	"runtime"
+)
+
+func BuildMultiLinestring(rel *element.Relation, srid int) (*geos.Geom, error) {
+	g := geos.NewGeos()
+	g.SetHandleSrid(srid)
+	defer g.Finish()
+
+	var lines []*geos.Geom
+
+	for _, member := range rel.Members {
+		if member.Way == nil {
+			continue
+		}
+
+		line, err := LineString(g, member.Way.Nodes)
+
+		// Clear the finalizer created in LineString()
+		// as we want to make the object a part of MultiLineString.
+		runtime.SetFinalizer(line, nil)
+
+		if err != nil {
+			return nil, err
+		}
+
+		lines = append(lines, line)
+	}
+
+	result := g.MultiLineString(lines)
+	if result == nil {
+		return nil, errors.New("Error while building multi-linestring.")
+	}
+
+	g.DestroyLater(result)
+
+	return result, nil
+}

geom/multilinestring_test.go

@@ -0,0 +1,43 @@
+package geom
+
+import (
+	"testing"
+
+	"github.com/omniscale/imposm3/element"
+	"github.com/omniscale/imposm3/geom/geos"
+)
+
+func TestSimpleMultiLineString(t *testing.T) {
+	w1 := makeWay(1, element.Tags{}, []coord{
+		{1, 1, 0},
+		{2, 2, 0},
+	})
+	w2 := makeWay(2, element.Tags{}, []coord{
+		{3, 2, 0},
+		{4, 3, 0},
+	})
+
+	rel := element.Relation{
+		OSMElem: element.OSMElem{Id: 1, Tags: element.Tags{}}}
+	rel.Members = []element.Member{
+		{Id: 1, Type: element.WAY, Role: "", Way: &w1},
+		{Id: 2, Type: element.WAY, Role: "", Way: &w2},
+	}
+
+	geom, err := BuildMultiLinestring(&rel, 3857)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	g := geos.NewGeos()
+	defer g.Finish()
+
+	if !g.IsValid(geom) {
+		t.Fatal("geometry not valid", g.AsWkt(geom))
+	}
+
+	if length := geom.Length(); length != 2 {
+		t.Fatal("length invalid", length)
+	}
+}

import_/import.go

@@ -180,6 +180,7 @@ func Import(importOpts config.Import) {
 			tagmapping.Conf.SingleIdSpace,
 			relations,
 			db, progress,
+			tagmapping.LineStringMatcher,
 			tagmapping.PolygonMatcher,
 			tagmapping.RelationMatcher,
 			tagmapping.RelationMemberMatcher,

mapping/mapping.go

@@ -84,7 +84,7 @@ const (
 type Mapping struct {
 	Conf                  config.Mapping
 	PointMatcher          NodeMatcher
-	LineStringMatcher     WayMatcher
+	LineStringMatcher     RelWayMatcher
 	PolygonMatcher        RelWayMatcher
 	RelationMatcher       RelationMatcher
 	RelationMemberMatcher RelationMatcher
@@ -356,6 +356,11 @@ func (m *Mapping) addRelationFilters(tableType TableType, filters tableElementFi
 					return false
 				}
 				filters[name] = append(filters[name], f)
+			} else if TableType(t.Type) == LineStringTable {
+				f := func(tags element.Tags, key Key, closed bool) bool {
+					return false
+				}
+				filters[name] = append(filters[name], f)
 			}
 		}
 	}

mapping/matcher.go

@@ -20,17 +20,20 @@ func (m *Mapping) pointMatcher() (NodeMatcher, error) {
 	}, err
 }
 
-func (m *Mapping) lineStringMatcher() (WayMatcher, error) {
+func (m *Mapping) lineStringMatcher() (RelWayMatcher, error) {
 	mappings := make(TagTableMapping)
 	m.mappings(LineStringTable, mappings)
 	filters := make(tableElementFilters)
 	m.addFilters(filters)
 	m.addTypedFilters(LineStringTable, filters)
+	relFilters := make(tableElementFilters)
+	m.addRelationFilters(LineStringTable, relFilters)
 	tables, err := m.tables(LineStringTable)
 	return &tagMatcher{
 		mappings:   mappings,
 		filters:    filters,
 		tables:     tables,
+		relFilters: relFilters,
 		matchAreas: false,
 	}, err
 }