gis.road_graph

Parameters

Name	Type	Mode
		IN

Definition

DECLARE
    edges_data record;
    merge_result boolean;
    _set_config text;
    raise_notice text;
BEGIN
    -- Set config to avoid the other triggers (after edge actions)
    -- to delete it again, which will raise an exception
    SELECT set_config('road.graph.node.already.deleted', OLD.id::text, true)
    INTO _set_config
    ;

-- Trigger disabled by session variable
    IF road_graph.get_current_setting('road.graph.disable.trigger', '0') = '1'
    THEN
        RETURN OLD;
    END IF;

-- Check if we must log
    raise_notice = road_graph.get_current_setting('road.graph.raise.notice', 'no');

-- Check if the node is linked to exactly two edges of the same road
    -- If not, raise an exception
    -- If yes, merge the two edges
    SELECT INTO edges_data
        count(*) AS nb_edges,
        array_agg(DISTINCT e.road_code) AS road_codes,
        array_agg(e.id) AS edge_ids
    FROM road_graph.edges AS e
    WHERE True
    AND OLD.id IN (e.start_node, e.end_node)
    ;
    -- Return OLD if the node is not linked to an edge
    IF edges_data.nb_edges = 0 THEN
        IF raise_notice IN ('info', 'debug') THEN
            RAISE NOTICE '% BEFORE NODE % n° % %, node is not linked to any edge',
                repeat('    ', pg_trigger_depth()::integer),
                TG_OP, OLD.id, ST_AsText(OLD.geom)
            ;
        END IF;
        RETURN OLD;
    END IF;

-- Log
    IF raise_notice IN ('info', 'debug') THEN
        RAISE NOTICE '% BEFORE NODE % n° % %, node is linked to % edge(s) and % road code(s)',
            repeat('    ', pg_trigger_depth()::integer),
            TG_OP, OLD.id, ST_AsText(OLD.geom),
            edges_data.nb_edges,
            array_length(edges_data.road_codes, 1)
        ;
    END IF;

-- Raise an exception if the node is linked to more than two edges or to two edges with different road codes
    IF edges_data.nb_edges != 2 OR array_length(edges_data.road_codes, 1) != 1 THEN
        RAISE EXCEPTION 'Node n° % cannot be deleted because it is linked to % edge(s) and % road code(s)',
            OLD.id, edges_data.nb_edges, array_length(edges_data.road_codes, 1);
    END IF;

-- Merge the two edges
    IF raise_notice IN ('info', 'debug') THEN
        RAISE NOTICE 'We must merge - % ',
            array_to_string(edges_data.edge_ids, ' et ')
        ;
    END IF;
    SELECT road_graph.merge_edges(edges_data.edge_ids[1], edges_data.edge_ids[2]) AS merge_edges
    INTO merge_result;

RETURN OLD;
END;

before_node_delete()

Description

Parameters

Definition