def csvwritein(doc):# doc is a django model contains the information of the uploading file
        doc = doc
        conn = psycopg2.connect("dbname='apidb' user='api' host='localhost' password='eric40502' port='5432'")
        readcur = conn.cursor()
        readcur.execute("select exists(select * from information_schema.tables where table_name='%s')" % doc.tablename) # check if same relation is already in database
        check = readcur.fetchone()[0]# check is used to check if same relation exists
        print(check)
        try:# change encoding type according to file type
                fr = open(doc.path,encoding = 'utf-8-sig')
                dr(fr,doc,check)# pass writing database part to another func
                fr.close()
        except Exception as e:
                fr = open(doc.path,encoding = 'big5')
                dr(fr,doc,check)# pass writing database part to another func
                fr.close()
        conn.commit()

def dr(fr,doc,check): # make datareader as function to keep code 'dry'
        csvt = 0 # check if writing action is first time
        row_id = 1 # used for following id field
        conn = psycopg2.connect("dbname='apidb' user='api' host='localhost' password='eric40502' port='5432'")
        maincur = conn.cursor()
        writecur = conn.cursor()
        datareader = csv.reader(fr, delimiter=',')
        for row in datareader:
                 if csvt == 0: # first time in loop(create field) and check no same file exists
                         print(doc.tablename)
                         if check == True:
                                 checktrue(doc)
                         else:
                                 tablename = '"%s"' % doc.tablename
                         maincur.execute("CREATE TABLE %s (id SERIAL PRIMARY KEY);" % tablename)
                         row_count = sum(1 for line in datareader)
                         col_count = len(row)
                         frow = row
                         for i in range(0,col_count,1):
                                 row[i] = '"%s"' % row[i] # change number to string
                                 maincur.execute("ALTER TABLE %s ADD %s CITEXT;" % (tablename,row[i]$
                         csvt = csvt+1
                         fr.seek(0)
                         next(datareader)
                 elif csvt > 0: # not first time(insert data) and check no same file exists
                         for j in range(0,col_count,1):
                                 if j == 0:
                                         writecur.execute("INSERT INTO %s (%s) VALUES ('%s');" % (ta$
                                 else:
                                         writecur.execute("UPDATE %s SET %s = '%s' WHERE id = '%d';"$
                         csvt = csvt+1
                         row_id = row_id+1
                 else:
                         break
         conn.commit()
         maincur.close()
         writecur.close()
         conn.close()
         csvt = 0
         doc = Document.objects.all()