Unexpected type error when export data from table to text file

Question

I am trying to export the data from the table to txt file. I have code as follows

class Optimization_goolge(object):
    def __init__(self):
        self.dbname = ""
        self.usr_name = ""
        self.usr_pass = ""
        self.con = ""
        self.cur = ""
        self.openTime=""

    def vT(self, x, y, z, openTime):
        try:
            con_string="dbname = '%s' user = '%s' password ='%s' host = 'localhost'"%(x,y,z)
            con = psycopg2.connect(con_string)
            con.set_isolation_level(0)
            cur = con.cursor()

            cur.execute(("""COPY (select source, target, sum(cost)/1000 as cost from distance_matrix where source != 88888888 and target
             != 88888888 group by source, target order by source) TO '%s\\vrp_distance.txt'""") % (os.getcwd()))
            con.commit()

But I am getting error

error vT Function could not open file "D:\working_copy\vrp_distance.txt" for writing: No such file or directory

Error optimizeFxn_google arguments did not match any overloaded call:
  QMessageBox.warning(QWidget, QString, QString, QMessageBox.StandardButtons buttons=QMessageBox.Ok, QMessageBox.StandardButton defaultButton=QMessageBox.NoButton): argument 1 has unexpected type 'Optimization_goolge'
  QMessageBox.warning(QWidget, QString, QString, int, int, int button2=0): argument 1 has unexpected type 'Optimization_goolge'
  QMessageBox.warning(QWidget, QString, QString, QString, QString button1Text=QString(), QString button2Text=QString(), int defaultButtonNumber=0, int escapeButtonNumber=-1): argument 1 has unexpected type 'Optimization_goolge'

As it comes from `getcwd()` I guess the directory exists. Do you have writing permissions? Moreover, you should use `os.path.join()` to join paths instead of your manual way. You can additionally use `.format()` to increase readability. — mikuszefski, Jun 07 '18 at 08:27
@mikuszefski yes directory and file do exist. how to use format(). can you give me an example — user1687891, Jun 07 '18 at 08:32

Evgeny · Answer 1 · 2018-06-07T09:37:13.363

2

Try:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))
filepath = os.path.join(dir_path, 'vrp_distance.txt')

sql_statement = ("COPY (select source, target, sum(cost)/1000" 
" as cost from distance_matrix where source != 88888888 and target"
" != 88888888 group by source, target order by source) TO"
" '{}'".format(filepath))

Sidenotes to consider (not in original question):

why not separate responsibilities to extract information and write it to file - you will knwo for sure which part fails
OptimizationGoolge, by convention
if you init a class with null strings, something is wrong in class design
rename vT to somehting meaningful

You have to check too:

assert os.path.exists('D:/working_copy/vrp_distance.txt') 
assert os.path.exists('D:/working_copy')

Also check Save PL/pgSQL output from PostgreSQL to a CSV file. If you do not have a writing permission, all of the above is fruitless.

edited Jun 07 '18 at 09:37

answered Jun 07 '18 at 08:33

Evgeny

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Yes your code could remove all the error which brings back to my same error error vT Function could not open file "D:\working_copy\vrp_distance.txt" for writing: No such file or directory – user1687891 Jun 07 '18 at 09:22
result of filepath is D:\working_copy\vrp_distance.txt – user1687891 Jun 07 '18 at 09:33
And the asserts pass? @user1687891 – Evgeny Jun 07 '18 at 09:37
I think the multiline string needs a backslash line continuation. – mikuszefski Jun 07 '18 at 11:30
... by convention you refer to PEP8? – mikuszefski Jun 07 '18 at 11:32
@mikuszafski, if parts are in parenthesis, it does not – Evgeny Jun 07 '18 at 11:32
PEP8 suggests you CapWords for class names – Evgeny Jun 07 '18 at 11:39
my database is in different server and my code is local – user1687891 Jun 08 '18 at 04:30
that my be a reason - this code attempts to write to remote server. if you have a path relative from the server, you can supply that (eg on a local networ, otherwise the solution is to get the select result and save it locally. – Evgeny Jun 08 '18 at 06:26

Unexpected type error when export data from table to text file

1 Answers1