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pypg.py
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pypg.py
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# -*- coding:utf-8 -*-
"""
PyPg - R. Souweine, 2016.
"""
import sys
import os.path
import ConfigParser
from datetime import datetime
import psycopg2
import psycopg2.extras
import pandas.io.sql as psql
import geopandas as gpd
from sqlalchemy import create_engine
import warnings
warnings.simplefilter(action = "ignore", category = FutureWarning)
class PgDb:
"""
Crée un objet base de données, connecté à PostgreSQL.
Nécessite
- Un fichier de configuration *.cfg
- Ou une liste [host, lgn, pwd, bdd, port] avec la variable cfg_list.
Ouvre automatiquement une connexion à la création de l'objet.
"""
def __init__(self, config_file="", config_section="Connection", debug=False, con=None, cur=None, cfg_list=[]):
"""
Initialisation et connection
"""
if len(cfg_list) > 0:
# Lecture de la configuration à partir de la liste
self.config_file = None
self.config_section = None
self.config = None
self.host = cfg_list[0]
self.lgn = cfg_list[1]
self.pwd = cfg_list[2]
self.bdd = cfg_list[3]
self.port = cfg_list[4]
self.debug = debug
else:
# Lecture de la configuration avec le fichier
if os.path.isfile(config_file):
self.config_file = config_file
self.config_section = config_section
self.config = ConfigParser.ConfigParser()
self.config.read(config_file)
self.host = self.ConfigSectionMap(self.config, self.config_section)['host']
self.lgn = self.ConfigSectionMap(self.config, self.config_section)['lgn']
self.pwd = self.ConfigSectionMap(self.config, self.config_section)['pwd']
self.bdd = self.ConfigSectionMap(self.config, self.config_section)['bdd']
self.port = self.ConfigSectionMap(self.config, self.config_section)['port']
self.debug = debug
else:
self.error("%s is doesn't exists." % config_file, exit=True)
# Connection à pgsql
try:
self.con = psycopg2.connect(host=self.host,user=self.lgn,
password=self.pwd, database=self.bdd)
self.cur = self.con.cursor(cursor_factory =
psycopg2.extras.RealDictCursor)
except psycopg2.DatabaseError, e:
self.error("%s" % e)
# Creation du moteur SQL Alchemy
self.engine = create_engine("postgresql://%s:%s@%s:%s/%s" % (self.lgn, self.pwd, self.host, self.port, self.bdd))
if self.debug == True:
self.info("Connecté à %s" % self.bdd)
def connect_to_db(self, db_name):
"""
Disconnect then connect to new database.
"""
self.disconnect()
self.bdd = db_name
try:
self.con = psycopg2.connect(host=self.host,user=self.lgn,
password=self.pwd, database=self.bdd)
self.cur = self.con.cursor(cursor_factory =
psycopg2.extras.RealDictCursor)
except psycopg2.DatabaseError, e:
self.error("%s" % e)
def info(self, msg):
print "%s PgDb > %s" % (datetime.now().strftime('%Y-%m-%d %H:%M'), msg)
def warning(self, msg):
print "%s PgDb > WARNING: %s" % (datetime.now().strftime('%Y-%m-%d %H:%M'), msg)
def error(self, msg, exit=False):
print "%s PgDb > ERROR: %s" % (datetime.now().strftime('%Y-%m-%d %H:%M'), msg)
if exit is True:
sys.exit()
def ConfigSectionMap(self, config_object, section):
"""
Mapping des sections d'un fichier de config.
"""
section_dict = {}
options = config_object.options(section)
for option in options:
try:
section_dict[option] = config_object.get(section, option)
if section_dict[option] == -1:
self.warning("skip: %s" % option)
except:
self.warning("exception on %s!" % option)
section_dict[option] = None
return section_dict
def rm_accents(self, txt):
"""
Supprime les caracters speciaux
"""
for ch in ["é","è", "ê"]:
txt = txt.replace(ch, "e")
for ch in ["â","à"]:
txt = txt.replace(ch, "a")
for ch in ["ô"]:
txt = txt.replace(ch, "o")
for ch in ["û", "ù"]:
txt = txt.replace(ch, "u")
for ch in ["î", "i"]:
txt = txt.replace(ch, "i")
return txt
def format_null_values(self, sql):
"""
Replace Python None values to PostgreSQL NULL.
"""
sql = sql.replace("None", "NULL")
sql = sql.replace("'NULL'", "NULL")
return sql
def disconnect(self):
"""
Deconnexion de la session pgsql
"""
try:
self.cur.close()
self.con.close()
if self.debug is True:
self.info("Déconnecté de %s" % self.bdd)
except psycopg2.DatabaseError, e:
self.error("%s" % e)
def select(self, sql, commit=True, df=True):
"""
Execute une requete select pgsql et retourne
le résultat si il y en a un et la sortie
console.
"""
try:
if self.debug == True:
self.info("Sélection - %s" %sql)
if df == True:
df = psql.frame_query(sql, con=self.con)
if len(df) == 0 and self.debug is True:
self.warning("... Table vide")
if self.debug == True:
self.info("... Requête executée")
return df
else:
self.cur.execute(sql)
if self.debug == True:
self.info("... Requête executée: %s " %self.cur.statusmessage)
return self.cur.fetchall()
except psycopg2.DatabaseError, e:
self.error("%s" %e)
def execute(self, sql, commit=True, accents=False):
"""
Execute une requete pgsql qui ne renvoie pas de résultats.
"""
try:
if accents is True:
self.info("... Suppression des accents")
sql = self.rm_accents(sql)
sql = self.format_null_values(sql)
if self.debug == True:
self.info("Execution - %s" %sql)
psql.execute(u"%s" % sql, con=self.con, cur=self.cur)
self.con.commit()
if self.debug == True:
self.info("... Requete %s exécutée." %(self.cur.statusmessage))
except psycopg2.DatabaseError, e:
self.error("%s" %e)
def insert_df(self, df, schema, table, if_exists="append", index=False):
"""
Insertion d'une dataframe pandas dans PostgreSQL
if_exists : {‘fail’, ‘replace’, ‘append’}
"""
if self.debug is True:
self.info("Insertion de DataFrame dans %s%s mode = %s." %(schema, table, if_exists))
df.to_sql(table, self.engine, schema=schema, if_exists=if_exists, index=index)
if self.debug is True:
self.info("... Insertion de DataFrame exécutée.")
def maintenance(self, sql):
"""
Permets d'effectuer des requêtes de maintenance
sans se soucier des transactions.
(Pas de transactions pour ce type de requête.)
"""
try:
if self.debug == True:
self.info("Maintenance - %s" %sql)
self.old_isolation_level = self.con.isolation_level
self.con.set_isolation_level(0)
psql.execute(sql, con=self.con, cur=self.cur)
self.con.set_isolation_level(self.old_isolation_level)
if self.debug == True:
self.info("... Requete %s exécutée." %(self.cur.statusmessage))
except psycopg2.DatabaseError, e:
self.error("%s" %e)
def geoselect(self, sql, geom_col="geom"):
"""
Select PostgreSQL / PostGIS data in a GeoPandas GeoDataFrame.
"""
if self.debug is True:
self.info("Geoselect - %s" %sql)
gdf = gpd.read_postgis(sql, self.con, geom_col=geom_col)
if len(gdf) == 0:
self.warning("... Table vide")
if self.debug is True:
self.info("... Requête executée")
return gdf
if __name__ == "__main__":
test_carto = False
# Test de la classe PgDB
db = PgDb("configs/espace.cfg", debug=True)
df = db.select("SELECT id_polluant, nom_abrege_polluant FROM commun.tpk_polluants WHERE id_polluant in (38, 48);")
db.execute("DROP TABLE IF EXISTS public.toto; CREATE TABLE public.toto (id INTEGER, nom TEXT);")
db.insert_df(df, "public", "toto", "replace")
db.execute("INSERT INTO public.toto VALUES (8, 'téàîst'); INSERT INTO public.toto VALUES (8, '%s');" % None, accents=True)
db.maintenance("VACUUM ANALYZE public.toto;")
gdf = db.geoselect("SELECT * FROM cadastre.w_visu_carrieres_km;")
db.disconnect()
# Cartographie d'une GéoDataFrame
if test_carto is True:
import matplotlib
matplotlib.use('QT4Agg')
import matplotlib.pyplot as plt
plt.rcParams['figure.figsize'] = (18,11)
gdf.plot(column='val', colormap='YlOrRd', scheme='QUANTILES', k=8)
plt.show()
# Utilisation d'une section spécifique d'un fichier de config
db = PgDb("configs/global.cfg", config_section="inv", debug=True)
db.disconnect()