Join a list of strings such that each string is within quotes and comma separated

Question

Consider that I have a list of customer names:

lst = ['John','Jack','Martin']

The desired output in a variable: 'John','Jack','Martin'

I can use something like ",".join(lst) and then more string formatting to achieve this. Is there any clear and more direct approach to this?

My idea is to pass the elements of a string in a SQL where clause.

Answer 1

Do not use this for SQL query generation. Use the database driver SQL parameters instead. You cannot hope to properly escape your way out of SQL injection attacks otherwise.

If you need to use a WHERE .. IN .. test, generate placeholders:

query = 'SELECT * FROM table WHERE column IN ({})'.format(','.join(['%s'] * len(lst)))
cursor.execute(query, lst)

For everything else, use a list comprehension to add the quotes to the values, then join the results with commas:

', '.join(['"{}"'.format(value) for value in lst])

Demo:

>>> lst = ['John','Jack','Martin']
>>> ', '.join(['"{}"'.format(value) for value in lst])
'"John", "Jack", "Martin"'
>>> print ', '.join(['"{}"'.format(value) for value in lst])
"John", "Jack", "Martin"

This will consistently use " double quotes; simply use "'{}'" as the template if you must have single quotes instead.