我有一些问题，设计出使用说明psycopg2库的规范一个好的算法在这里
我想建立等于该字符串动态查询：
SELECT ST_GeomFromText('POLYGON((0.0 0.0,20.0 0.0,20.0 20.0,0.0 20.0,0.0 0.0))');
正如你所看到的，我的Polygon对象包含多个点，其中包含一个简单的CSV文件some.csv阅读：
0.0;0.0
20.0;0.0
20.0;20.0
0.0;20.0
0.0;0.0
所以我构建查询动态，线路/数据的在CSV数的函数。
在这里我的程序生成的SQL查询字符串来执行：
import psycopg2
import csv
# list of points
lXy = []
DSN= "dbname='testS' user='postgres' password='postgres' host='localhost'"
conn = psycopg2.connect(DSN)
curs = conn.cursor()
def genPointText(curs,x,y):
generatedPoint = "%s %s" % (x,y)
return generatedPoint
#Lecture fichier csv
polygonFile = open('some.csv', 'rb')
readerCSV = csv.reader(polygonFile,delimiter = ';')
for coordinates in readerCSV:
lXy.append(genPointText(curs,float(coordinates[0]),float(coordinates[1])))
# function of list concatenation by separator
def convert(myList,separator):
return separator.join([str(i) for i in myList])
# construct simple query with psycopg
def genPolygonText(curs,l):
# http://initd.org/psycopg/docs/usage.html#python-types-adaptation
generatedPolygon = "POLYGON((%s))" % convert(l, ",")
return generatedPolygon
def executeWKT(curs,geomObject,srid):
try:
# geometry ST_GeomFromText(text WKT, integer srid);
finalWKT = "SELECT ST_GeomFromText('%s');" % (geomObject)
print finalWKT
curs.execute(finalWKT)
except psycopg2.ProgrammingError,err:
print "ERROR = " , err
polygonQuery = genPolygonText(curs,lXy)
executeWKT(curs,polygonQuery,4326)
正如你所看到的，这是工作，但这种方式是不是因为Python对象和SQL PostgreSQL的对象之间的转换问题是正确的。
在文档中，我只看到例如饲料和数据转换为静态查询。 你知道一个“优雅”的方式在动态建立查询以创建正确的字符串与正确的类型？
更新1：
正如你所看到的，当我在这个简单的例子使用psycopg类型的转换功能，我有这样的错误：
query = "ST_GeomFromText('POLYGON(( 52.146542 19.050557, 52.148430 19.045527, 52.149525 19.045831, 52.147400 19.050780, 52.147400 19.050780, 52.146542 19.050557))',4326)"
name = "my_table"
try:
curs.execute('INSERT INTO %s(name, url, id, point_geom, poly_geom) VALUES (%s);', (name,query))
except psycopg2.ProgrammingError,err:
print "ERROR = " , err
错误等于：
ERROR = ERREUR: erreur de syntaxe sur ou près de « E'my_table' »
LINE 1: INSERT INTO E'my_table'(name, poly_geom) VALUES (E'ST_GeomFr...
更新2：
最终的代码工作，感谢StackOverflow的用户！
#info lib : http://www.initd.org/psycopg/docs/
import psycopg2
# info lib : http://docs.python.org/2/library/csv.html
import csv
# list of points
lXy = []
DSN= "dbname='testS' user='postgres' password='postgres' host='localhost'"
print "Opening connection using dns:", DSN
conn = psycopg2.connect(DSN)
curs = conn.cursor()
def genPointText(curs,x,y):
generatedPoint = "%s %s" % (x,y)
return generatedPoint
#Lecture fichier csv
polygonFile = open('some.csv', 'rb')
readerCSV = csv.reader(polygonFile,delimiter = ';')
for coordinates in readerCSV:
lXy.append(genPointText(curs,float(coordinates[0]),float(coordinates[1])))
# function of list concatenation by separator
def convert(myList,separator):
return separator.join([str(i) for i in myList])
# construct simple query with psycopg
def genPolygonText(l):
# http://initd.org/psycopg/docs/usage.html#python-types-adaptation
generatedPolygon = "POLYGON((%s))" % convert(l, ",")
return generatedPolygon
def generateInsert(curs,tableName,name,geomObject):
curs.execute('INSERT INTO binome1(name,geom) VALUES (%s, %s);' , (name,geomObject))
def create_db_binome(conn,name):
curs = conn.cursor()
SQL = (
"CREATE TABLE %s"
" ("
" polyname character varying(15),"
" geom geometry,"
" id serial NOT NULL,"
" CONSTRAINT id_key PRIMARY KEY (id)"
" )"
" WITH ("
" OIDS=FALSE"
" );"
" ALTER TABLE %s OWNER TO postgres;"
) %(name,name)
try:
#print SQL
curs.execute(SQL)
except psycopg2.ProgrammingError,err:
conn.rollback()
dropQuery = "ALTER TABLE %s DROP CONSTRAINT id_key; DROP TABLE %s;" % (name,name)
curs.execute(dropQuery)
curs.execute(SQL)
conn.commit()
def insert_geometry(polyname,tablename,geometry):
escaped_name = tablename.replace('""','""')
try:
test = 'INSERT INTO %s(polyname, geom) VALUES(%%s, ST_GeomFromText(%%s,%%s))' % (escaped_name)
curs.execute(test, (tablename, geometry, 4326))
conn.commit()
except psycopg2.ProgrammingError,err:
print "ERROR = " , err
################
# PROGRAM MAIN #
################
polygonQuery = genPolygonText(lXy)
srid = 4326
table = "binome1"
create_db_binome(conn,table)
insert_geometry("Berlin",table,polygonQuery)
insert_geometry("Paris",table,polygonQuery)
polygonFile.close()
conn.close()
