Python string concatenation append variable to path what is the correct syntax missing closing quote error

Question

I am trying to append a string value of a variable to end of a string. I am getting a missing closing quote.

My Python snippet is:

from Utilities.HelperMethods import read_from_file

class DataCategoriesPage_TestCase(BaseTestCase):
    def test_00001_add_data_categories(self):
        project_name = read_from_file("project_name")
        administration_page.enter_location_for_export(r"\\STORAGE-1\Testing\Test Data\ClearCore\Exports\5\" + project_name)

What is the correct syntax?

The value of the variable project name is "selenium_regression_project_09/04/2016"

I would like to add this to the end of the string path \\STORAGE-1\Testing\Test Data\ClearCore\Exports\5\

Martijn Pieters · Accepted Answer · 2016-04-09 16:05:11Z

4

You can't end a raw string literal with a \, because a backslash can still be used to escape a quote. Quoting the string literal documentation (from the section on raw string literals):

String quotes can be escaped with a backslash, but the backslash remains in the string; for example, r"\"" is a valid string literal consisting of two characters: a backslash and a double quote; r"\" is not a valid string literal (even a raw string cannot end in an odd number of backslashes). Specifically, a raw string cannot end in a single backslash (since the backslash would escape the following quote character).

This looks like a file path, so use os.path.join() to concatenate the file path parts:

import os.path

administration_page.enter_location_for_export(
    os.path.join(
        r"\\STORAGE-1\Testing\Test Data\ClearCore\Exports\5",
        project_name))

Note that the raw string no longer needs to end with a backslash now.

edited Apr 9, 2016 at 16:05

answered Apr 9, 2016 at 16:00

Martijn Pieters

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2 Comments

Jason Over a year ago

This is because the backslash is escaping the closing quotes

Riaz Ladhani Over a year ago

Thanks for your help. Got it now.

Martin Bonner supports Monica · Accepted Answer · 2016-04-09 16:09:27Z

2

Martijn Peters has given the correct answer for your problem (use os.path.join), but there is a solution to the problem of having a literal with lots of back-slashes (so you want to write it as a raw literal), that ends with a back slash. The solution is to write most of it as a raw literal, but write the trailing back-slash as an ordinary (escaped) literal. Python will concatenate two adjacent string literals into one. So in your case, the literal would be written as:

    r"\\STORAGE-1\Testing\Test Data\ClearCore\Exports\5" "\\"

This could conceivably be useful to someone writing some other back-slash heavy code (e.g. regular expressions).

answered Apr 9, 2016 at 16:09

Martin Bonner supports Monica

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Comments

Jefinthejam · Accepted Answer · 2016-04-09 16:08:49Z

1

Apparently you can't end a raw string with a backslash - that will escape the final quotation mark. (Bug?). Try:

r"\\STORAGE-1\Testing\Test Data\ClearCore\Exports\5" + "\\" + project_name

answered Apr 9, 2016 at 16:08

Jefinthejam

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1 Comment

Martin Bonner supports Monica Over a year ago

It's not a bug, it's a deliberate design decision. It means you can embed a quote in the string by back-slash escaping it.

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