TypeError: sequence item 0: expected string, int found

I am attempting to insert data from a dictionary into a database. I want to iterate over the values and format them accordingly, depending on the data type. Here is a snippet of the code I am using:

def _db_inserts(dbinfo):
    try:
        rows = dbinfo['datarows']

        for row in rows:
            field_names = ",".join(["'{0}'".format(x) for x in row.keys()])
            value_list = row.values()

            for pos, value in enumerate(value_list):
                if isinstance(value, str):
                    value_list[pos] = "'{0}'".format(value)
                elif isinstance(value, datetime):
                    value_list[pos] = "'{0}'".format(value.strftime('%Y-%m-%d'))

            values = ",".join(value_list)

            sql = "INSERT INTO table_foobar ({0}) VALUES ({1})".format(field_names, values)

    except Exception as e:
        print 'BARFED with msg:',e

When I run the algo using some sample data (see below), I get the error:

TypeError: sequence item 0: expected string, int found

An example of a value_list data which gives the above error is:

value_list = [377, -99999, -99999, 'f', -99999, -99999, -99999, 1108.0999999999999, 0, 'f', -99999, 0, 'f', -99999, 'f', -99999, 1108.0999999999999, -99999, 'f', -99999, 'f', -99999, 'f', 'f', 0, 1108.0999999999999, -99999, -99999, 'f', 'f', 'f', -99999, 'f', '1984-04-02', -99999, 'f', -99999, 'f', 1108.0999999999999]

What am I doing wrong?

Answers:

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Method 1

string.join connects elements inside list of strings, not ints.

Use this generator expression instead :

values = ','.join(str(v) for v in value_list)

Method 2

Although the given list comprehension / generator expression answers are ok, I find this easier to read and understand:

values = ','.join(map(str, value_list))

Method 3

Replace

values = ",".join(value_list)

with

values = ','.join([str(i) for i in value_list])

OR

values = ','.join(str(value_list)[1:-1])

Method 4

The answers by cval and Priyank Patel work great. However, be aware that some values could be unicode strings and therefore may cause the str to throw a UnicodeEncodeError error. In that case, replace the function str by the function unicode.

For example, assume the string Libië (Dutch for Libya), represented in Python as the unicode string u'Libixeb':

print str(u'Libixeb')

throws the following error:

Traceback (most recent call last):
  File "/Users/tomasz/Python/MA-CIW-Scriptie/RecreateTweets.py", line 21, in <module>
    print str(u'Libixeb')
UnicodeEncodeError: 'ascii' codec can't encode character u'xeb' in position 4: ordinal not in range(128)

The following line, however, will not throw an error:

print unicode(u'Libixeb') # prints Libië

So, replace:

values = ','.join([str(i) for i in value_list])

by

values = ','.join([unicode(i) for i in value_list])

to be safe.

Method 5

String interpolation is a nice way to pass in a formatted string.

values = ', '.join('$%s' % v for v in value_list)

Method 6

you can convert the integer dataframe into string first and then do the operation e.g.

df3['nID']=df3['nID'].astype(str)
grp = df3.groupby('userID')['nID'].aggregate(lambda x: '->'.join(tuple(x)))

Method 7

solution:

    email = ''.join([str(nip), settings.ORGANISATION_EMAIL_SUFFIX])

Method 8

Elements inside the list are not in the string format for this first we need to convert it to string then we can apply the join operation on that list as below :

summary = [ str(i) for i in summary ]
summery = " ".join(summary)

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0