import os import sys if sys.version_info[0] > 2 : from transport.common import Reader, Writer #, factory else: from common import Reader,Writer # import nujson as json import json # from threading import Lock import sqlite3 import pandas as pd from multiprocessing import Lock class DiskReader(Reader) : """ This class is designed to read data from disk (location on hard drive) @pre : isready() == True """ def __init__(self,**params): """ @param path absolute path of the file to be read """ Reader.__init__(self) self.path = params['path'] if 'path' in params else None self.delimiter = params['delimiter'] if 'delimiter' in params else ',' def isready(self): return os.path.exists(self.path) def meta(self,**_args): return [] def read(self,**args): _path = self.path if 'path' not in args else args['path'] _delimiter = self.delimiter if 'delimiter' not in args else args['delimiter'] return pd.read_csv(_path,delimiter=self.delimiter) def stream(self,**args): """ This function reads the rows from a designated location on disk @param size number of rows to be read, -1 suggests all rows """ size = -1 if 'size' not in args else int(args['size']) f = open(self.path,'rU') i = 1 for row in f: i += 1 if size == i: break if self.delimiter : yield row.split(self.delimiter) yield row f.close() class DiskWriter(Writer): """ This function writes output to disk in a designated location. The function will write a text to a text file - If a delimiter is provided it will use that to generate a xchar-delimited file - If not then the object will be dumped as is """ THREAD_LOCK = Lock() def __init__(self,**params): super().__init__() self._path = params['path'] self._delimiter = params['delimiter'] if 'delimiter' in params else None self._mode = 'w' if 'mode' not in params else params['mode'] # def meta(self): # return self.cache['meta'] # def isready(self): # """ # This function determines if the class is ready for execution or not # i.e it determines if the preconditions of met prior execution # """ # return True # # p = self.path is not None and os.path.exists(self.path) # # q = self.name is not None # # return p and q # def format (self,row): # self.cache['meta']['cols'] += len(row) if isinstance(row,list) else len(row.keys()) # self.cache['meta']['rows'] += 1 # return (self.delimiter.join(row) if self.delimiter else json.dumps(row))+"\n" def write(self,info,**_args): """ This function writes a record to a designated file @param label @param row row to be written """ try: DiskWriter.THREAD_LOCK.acquire() _delim = self._delimiter if 'delimiter' not in _args else _args['delimiter'] _path = self._path if 'path' not in _args else _args['path'] _mode = self._mode if 'mode' not in _args else _args['mode'] info.to_csv(_path,index=False,sep=_delim) pass except Exception as e: # # Not sure what should be done here ... pass finally: DiskWriter.THREAD_LOCK.release() class SQLite : def __init__(self,**_args) : self.path = _args['database'] if 'database' in _args else _args['path'] self.conn = sqlite3.connect(self.path,isolation_level="IMMEDIATE") self.conn.row_factory = sqlite3.Row self.fields = _args['fields'] if 'fields' in _args else [] def has (self,**_args): found = False try: if 'table' in _args : table = _args['table'] sql = "SELECT * FROM :table limit 1".replace(":table",table) _df = pd.read_sql(sql,self.conn) found = _df.columns.size > 0 except Exception as e: pass return found def close(self): try: self.conn.close() except Exception as e : print(e) def apply(self,sql): try: if not sql.lower().startswith('select'): cursor = self.conn.cursor() cursor.execute(sql) cursor.close() self.conn.commit() else: return pd.read_sql(sql,self.conn) except Exception as e: print (e) class SQLiteReader (SQLite,DiskReader): def __init__(self,**args): super().__init__(**args) # DiskReader.__init__(self,**args) # self.path = args['database'] if 'database' in args else args['path'] # self.conn = sqlite3.connect(self.path,isolation_level=None) # self.conn.row_factory = sqlite3.Row self.table = args['table'] if 'table' in args else None def read(self,**args): if 'sql' in args : sql = args['sql'] elif 'filter' in args : sql = "SELECT :fields FROM ",self.table, "WHERE (:filter)".replace(":filter",args['filter']) sql = sql.replace(":fields",args['fields']) if 'fields' in args else sql.replace(":fields","*") else: sql = ' '.join(['SELECT * FROM ',self.table]) if 'limit' in args : sql = sql + " LIMIT "+args['limit'] return pd.read_sql(sql,self.conn) def close(self): try: self.conn.close() except Exception as e : pass class SQLiteWriter(SQLite,DiskWriter) : connection = None LOCK = Lock() def __init__(self,**args): """ :path :fields json|csv """ # DiskWriter.__init__(self,**args) super().__init__(**args) self.table = args['table'] if 'table' in args else None # self.conn = sqlite3.connect(self.path,isolation_level="IMMEDIATE") # self.conn.row_factory = sqlite3.Row # self.fields = args['fields'] if 'fields' in args else [] if self.fields and not self.isready() and self.table: self.init(self.fields) SQLiteWriter.connection = self.conn def init(self,fields): self.fields = fields; sql = " ".join(["CREATE TABLE IF NOT EXISTS ",self.table," (", ",".join(self.fields),")"]) cursor = self.conn.cursor() cursor.execute(sql) cursor.close() self.conn.commit() def isready(self): try: sql = "SELECT count(*) FROM sqlite_master where name=':table'" sql = sql.replace(":table",self.table) cursor = self.conn.cursor() r = cursor.execute(sql) r = r.fetchall() cursor.close() return r[0][0] != 0 except Exception as e: pass return 0 # # If the table doesn't exist we should create it # def write(self,info,**_args): """ """ #if not self.fields : # #if type(info) == pd.DataFrame : # # _columns = list(info.columns) # #self.init(list(info.keys())) if type(info) == dict : info = [info] elif type(info) == pd.DataFrame : info = info.fillna('') info = info.to_dict(orient='records') if not self.fields : _rec = info[0] self.init(list(_rec.keys())) SQLiteWriter.LOCK.acquire() try: cursor = self.conn.cursor() sql = " " .join(["INSERT INTO ",self.table,"(", ",".join(self.fields) ,")", "values(:values)"]) for row in info : stream =["".join(["",value,""]) if type(value) == str else value for value in row.values()] stream = json.dumps(stream).replace("[","").replace("]","") self.conn.execute(sql.replace(":values",stream) ) # cursor.commit() self.conn.commit() # print (sql) except Exception as e : print (e) pass SQLiteWriter.LOCK.release()