class DataImporter(object):
"""
This class is a parent class which enable loading data to a PostgreSQL/PostGIS
database. It loads nothing by default."""
# SQL files to execute before loading data
PRELOADSQL = []
# SQL files to execute after loading data
POSTLOADSQL = []
def __init__(self, source="", dbstring="", logfile=None, doclean=True, subs = {}):
self.source = source
self.dbstring = dbstring
self.logfile = logfile
self.ploader = PsqlLoader(dbstring=self.dbstring, logfile=self.logfile)
self.doclean = doclean
self.substitutions = subs
def check_input(self):
"""Check if data input is ok."""
pass
def clean(self):
"""Clean temporary files."""
return True
def load(self):
ret = True
try:
self.check_input()
except StandardError as e:
sys.stderr.write("During import: %s\n" % e.message)
return False
ret = self.preload_sql()
if ret:
ret = self.load_data()
else:
sys.stderr.write("Error during preload_sql().\n")
if ret:
ret = self.postload_sql()
else:
sys.stderr.write("Error during load_data().\n")
if ret:
self.clean()
else:
sys.stderr.write("Error during postload_sql().\n")
return ret
def preload_sql(self):
return self.load_sqlfiles(self.PRELOADSQL)
def postload_sql(self):
return self.load_sqlfiles(self.POSTLOADSQL)
def load_sqlfiles(self, files, substitute = True):
"""Load some SQL files to the defined database.
Stop if one was wrong."""
ret = True
is_template = substitute and len(self.substitutions) > 0
for sqlfile in files:
filename = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'sql', sqlfile)
# Stop if one SQL execution was wrong
if ret and os.path.isfile(filename):
if is_template:
f = open(filename, 'r')
template = f.read()
self.ploader.set_from_template(template, self.substitutions)
else:
self.ploader.set_sqlfile(filename)
ret = self.ploader.load()
return ret
def load_data(self):
"""Load the data into the database."""
ret = True
return ret
def set_dbparams(self, dbstring = ""):
self.dbstring = dbstring
self.ploader.set_dbparams(dbstring)
