Question

尝试编写一个函数，该函数返回从 DEM 和高程插值在一条线上的点的几何形状，但收到此错误 ERROR: structure of query does not match function result type. 点末尾的查询应返回起点、终点和插值的几何形状区间的点。这是我的功能：

test_get_slope_profile

CREATE OR REPLACE FUNCTION test_get_slope_profile(ways_id bigint, interval_ float default 10, way_table TEXT DEFAULT 'ways')
    RETURNS TABLE(p_geom geometry, elevation float)
    LANGUAGE plpgsql
AS $function$
DECLARE 
    way_geom geometry;
    length_meters float;
    length_degree NUMERIC;
    translation_m_degree NUMERIC;
BEGIN
    
    IF way_table = 'ways' THEN 
        SELECT geom, length_m, ST_Length(geom) 
        INTO way_geom, length_meters, length_degree
        FROM ways
        WHERE id = ways_id; 
    ELSEIF way_table = 'ways_userinput' THEN 
        SELECT geom, length_m, ST_Length(geom) 
        INTO way_geom, length_meters, length_degree
        FROM ways_userinput 
        WHERE id = ways_id; 
    END IF;


    translation_m_degree = length_degree/length_meters;
    DROP TABLE IF EXISTS dump_points;
    IF length_meters > (2*interval_) THEN 
        CREATE TEMP TABLE dump_points AS 
        SELECT (ST_DUMP(ST_Lineinterpolatepoints(way_geom,interval_/length_meters))).geom AS geom;
    
    ELSEIF length_meters > interval_ AND length_meters < (2*interval_) THEN 
        CREATE TEMP TABLE dump_points AS 
        SELECT ST_LineInterpolatePoint(way_geom,0.5) AS geom;
        interval_ = length_meters/2;
    ELSE
        CREATE TEMP TABLE dump_points AS
        SELECT NULL::geometry AS geom;
    END IF;
        

    RETURN query
    WITH points AS 
    (
        SELECT ROW_NUMBER() OVER() cnt, geom, length_meters 
        FROM (
            SELECT st_startpoint(way_geom) AS geom
            UNION ALL 
            SELECT geom FROM dump_points
            UNION ALL 
            SELECT st_endpoint(way_geom) 
        ) x
    )

    SELECT 'geom', SUM(idw.val/(idw.distance/translation_m_degree))/SUM(1/(idw.distance/translation_m_degree))::real AS elev
    FROM points p, get_idw_values(geom) idw
    WHERE p.geom IS NOT NULL 
    GROUP BY cnt 
    ORDER BY cnt;


END;
$function$;

ERROR:  structure of query does not match function result type
DETAIL:  Returned type text does not match expected type geometry in column 1.
CONTEXT:  PL/pgSQL function test_get_slope_profile(bigint,double precision,text) line 38 at RETURN QUERY
SQL state: 42804

Answer 1

在 RETURN query 语句中，不要执行 SELECT 'geom', SUM(...))::real AS elev 而是执行 SELECT geom, SUM(...))::real AS elev

前者返回文本'geom'，后者返回列内容，即几何体

错误：查询结构与函数结果类型不匹配，返回类型文本与预期类型几何不匹配

1 个答案: