# Copyright (c) 2014 - 2017 Axel Wachtler
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# === imports ================================================================
from __future__ import print_function
import logging
import yaml
# === classes ==================================================================
[docs]class DbBase:
#: data structure that holds the schema of the DB
DbSchema = None
def __init__(self, dbschema, forcetables, **kwargs):
self.L = logging.getLogger("DbBase")
self.DbSchema = self.load_yaml_schema(dbschema)
sql = self.create_tables(force = forcetables)
for i,x in enumerate(sql):
self.L.debug("%d: %s", i, x)
self.query(x)
self.commit()
[docs] def load_yaml_schema(self, ymlfn):
"""load yaml file and store the schema in DbSchema"""
self.L.debug("load_yaml_schema: %s", ymlfn)
with open(ymlfn) as fh:
rv = yaml.safe_load(fh.read())
self.DbSchema = rv
assert rv.get('tables') != None
return rv
[docs] def create_tables(self, force = False):
"""returns a list of SQL commands that creates all tables given in the schema"""
commands = []
for tdescr in self.DbSchema.get("tables", []):
if force:
cmd = "DROP TABLE IF EXISTS `%s`;" % tdescr['name']
commands.append(cmd)
colspec = ["%s %s %s" % (col['field'], col['type'], col.get('default', '')) for col in tdescr['columns']]
cmd = "CREATE TABLE IF NOT EXISTS `%s`\n" % tdescr['name']
cmd += "(\n " + ",\n ".join(colspec) + '\n);'
commands.append(cmd)
self.L.debug("create table commands:\n - %s", "\n - ".join(commands))
return commands
[docs] def get_field_names(self):
"""returns dicitionary of all tables and their fieldnames"""
rv= {}
for t in self.DbSchema.get('tables'):
fields = []
for c in t['columns']:
dfl = c.get("default", "****")
self.L.debug("get_field_names: %s", c)
if dfl.find("PRIMARY KEY") < 0:
fields.append(c['field'])
rv[t['name']] = fields
return rv
# === interface functions =================================================
[docs] def execute_script(self, fn):
raise Exception("NotImplemented")
[docs] def get_tables(self):
raise Exception("NotImplemented")
[docs] def query(self, stmt):
raise Exception("NotImplemented")
[docs] def xquery(self, stmt):
raise Exception("NotImplemented")
[docs] def commit(self):
raise Exception("NotImplemented")