Postgis - 如何在插入之前检查几何类型

我有一个包含数百万行的postgres数据库,它有一个名为geom的列,它包含一个属性的边界.

使用python脚本我从该表中提取信息并将其重新插入到新表中.

当我在新表中插入时,脚本会出现以下错误:

Traceback (most recent call last):
  File "build_parcels.py", line 258, in 
    main()
  File "build_parcels.py", line 166, in main
    update_cursor.executemany("insert into parcels (par_id, street_add, title_no, proprietors, au_name, ua_name, geom) VALUES (%s, %s, %s, %s, %s, %s, %s)", inserts)
psycopg2.IntegrityError: new row for relation "parcels" violates check constraint "enforce_geotype_geom"

新表有一个检查约束enforce_geotype_geom =((geometrytype(geom)='POLYGON':: text)或(geom IS NULL))而旧表没有,所以我猜测theres dud数据或非多边形(也许是多边形数据) ？)在旧表中.我想将新数据保持为多边形,因此不想插入任何其他内容.

最初我尝试使用标准的python错误处理来包装查询,希望dud geom行会失败,但脚本会继续运行,但脚本已被写入最后提交而不是每行,所以它不起作用.

我认为我需要做的是遍历旧表geom行并检查它们是什么类型的几何体,这样我就可以确定是否要保留它或者在插入新表之前将其丢弃

什么是最好的解决方法？

这个令人惊讶的PostGIS SQL有用,可以帮助你解决这个问题......这里有很多几何类型测试:

-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-- 
-- $Id: cleanGeometry.sql 2008-04-24 10:30Z Dr. Horst Duester $
--
-- cleanGeometry - remove self- and ring-selfintersections from 
--                 input Polygon geometries 
-- http://www.sogis.ch
-- Copyright 2008 SO!GIS Koordination, Kanton Solothurn, Switzerland
-- Version 1.0
-- contact: horst dot duester at bd dot so dot ch
--
-- This is free software; you can redistribute and/or modify it under
-- the terms of the GNU General Public Licence. See the COPYING file.
-- This software is without any warrenty and you use it at your own risk
--  
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


CREATE OR REPLACE FUNCTION cleanGeometry(geometry)
  RETURNS geometry AS
$BODY$DECLARE
  inGeom ALIAS for $1;
  outGeom geometry;
  tmpLinestring geometry;

Begin

  outGeom := NULL;

-- Clean Process for Polygon 
  IF (GeometryType(inGeom) = 'POLYGON' OR GeometryType(inGeom) = 'MULTIPOLYGON') THEN

-- Only process if geometry is not valid, 
-- otherwise put out without change
    if not isValid(inGeom) THEN

-- create nodes at all self-intersecting lines by union the polygon boundaries
-- with the startingpoint of the boundary.  
      tmpLinestring := st_union(st_multi(st_boundary(inGeom)),st_pointn(boundary(inGeom),1));
      outGeom = buildarea(tmpLinestring);      
      IF (GeometryType(inGeom) = 'MULTIPOLYGON') THEN      
        RETURN st_multi(outGeom);
      ELSE
        RETURN outGeom;
      END IF;
    else    
      RETURN inGeom;
    END IF;


------------------------------------------------------------------------------
-- Clean Process for LINESTRINGS, self-intersecting parts of linestrings 
-- will be divided into multiparts of the mentioned linestring 
------------------------------------------------------------------------------
  ELSIF (GeometryType(inGeom) = 'LINESTRING') THEN

-- create nodes at all self-intersecting lines by union the linestrings
-- with the startingpoint of the linestring.  
    outGeom := st_union(st_multi(inGeom),st_pointn(inGeom,1));
    RETURN outGeom;
  ELSIF (GeometryType(inGeom) = 'MULTILINESTRING') THEN 
    outGeom := multi(st_union(st_multi(inGeom),st_pointn(inGeom,1)));
    RETURN outGeom;
  ELSIF (GeometryType(inGeom) = '' OR GeometryType(inGeom) = 'GEOMETRYCOLLECTION') THEN 
    RETURN NULL;
  ELSE 
    RAISE NOTICE 'The input type % is not supported %',GeometryType(inGeom),st_summary(inGeom);
    RETURN inGeom;
  END IF;     
End;$BODY$
  LANGUAGE 'plpgsql' VOLATILE;