Wrap linestrings/polygons in multi geometry if needed

Author: joto

src/output-flex.cpp

@@ -672,19 +672,24 @@ void output_flex_t::write_column(
         if (ltype == LUA_TUSERDATA) {
             auto const *const geom = unpack_geometry(lua_state(), -1);
             if (geom && !geom->is_null()) {
+                auto const type = column.type();
+                bool const wrap_multi =
+                    (type == table_column_type::multipoint ||
+                     type == table_column_type::multilinestring ||
+                     type == table_column_type::multipolygon);
                 if (geom->srid() == column.srid()) {
                     // OSM id not available here, so use dummy 0, it is used
                     // for debug messages only anyway.
                     m_expire.from_geometry(*geom, 0);
-                    copy_mgr->add_hex_geom(geom_to_ewkb(*geom));
+                    copy_mgr->add_hex_geom(geom_to_ewkb(*geom, wrap_multi));
                 } else {
                     auto const proj =
                         reprojection::create_projection(column.srid());
                     auto const tgeom = geom::transform(*geom, *proj);
                     // OSM id not available here, so use dummy 0, it is used
                     // for debug messages only anyway.
                     m_expire.from_geometry(tgeom, 0);
-                    copy_mgr->add_hex_geom(geom_to_ewkb(tgeom));
+                    copy_mgr->add_hex_geom(geom_to_ewkb(tgeom, wrap_multi));
                 }
             } else {
                 write_null(copy_mgr, column);

tests/bdd/flex/geometry-linestring.feature

@@ -0,0 +1,38 @@
+Feature: Creating linestring features from way
+
+    Scenario:
+        Given the grid
+            | 1 | 2 |   |
+            | 4 |   | 3 |
+            |   | 5 |   |
+        And the OSM data
+            """
+            w20 Thighway=motorway Nn1,n2,n3
+            w21 Thighway=motorway Nn4,n5
+            """
+        And the lua style
+            """
+            local lines = osm2pgsql.define_way_table('osm2pgsql_test_lines', {
+                { column = 'sgeom', type = 'linestring', projection = 4326 },
+                { column = 'mgeom', type = 'multilinestring', projection = 4326 },
+                { column = 'xgeom', type = 'multilinestring', projection = 4326 },
+            })
+
+            function osm2pgsql.process_way(object)
+                if object.tags.highway == 'motorway' then
+                    lines:insert({
+                        sgeom = object:as_linestring(),
+                        mgeom = object:as_multilinestring(),
+                        xgeom = object:as_linestring()
+                    })
+                end
+            end
+
+            """
+        When running osm2pgsql flex
+
+        Then table osm2pgsql_test_lines contains exactly
+            | way_id | ST_AsText(sgeom) | ST_AsText(ST_GeometryN(mgeom, 1)) | ST_AsText(ST_GeometryN(xgeom, 1)) |
+            | 20     | 1, 2, 3          | 1, 2, 3                           | 1, 2, 3                           |
+            | 21     | 4, 5             | 4, 5                              | 4, 5                              |
+