How to convert my list variable from a tuple to a string

Question

i am getting the following error:

index 0 has type 'tuple' but 'str' is expected

My list variable looks like this:

[('304',), ('316',), ('303',), ('BS S130',), ('Do Not Use',), ('17-4PH',), ('431S29',), ('416',), ('304',), ('316',), ('S143D',), ('15/5PH-H1025',), ('304S11',), ('316S11',), ('304L',), ('316L',), ('304S16',), ('BS S527',), ('316L',), ('316',), ('Misc',)]

def stainless_list(self):
    stainless_getlist = []

    content = 'SELECT grade FROM stainless ORDER BY prefix ASC'
    res = conn.execute(content)
    for row_index, row_data in enumerate(res):
        stainless_getlist.append(row_data)

    conn.close

    self.comboBox_2.clear()
    self.comboBox_2.addItems(stainless_getlist)

    print(stainless_getlist)
    return

How do i declare my list as a string instead of tuple so that it attaches to my combobox correctly?

blhsing · Accepted Answer · 2019-03-15 23:59:06Z

3

You can unpack the first item of each tuple as you iterate over the rows (and you don't need to enumerate as you are not using the row index).

Change:

for row_index, row_data in enumerate(res):
    stainless_getlist.append(row_data)

to:

for item, in res:
    stainless_getlist.append(item)

answered Mar 15, 2019 at 23:59

blhsing

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Bob McCormick · Accepted Answer · 2019-03-16 00:11:39Z

1

Your list is a list of tuples, where each tuple is a row of data. What may be confusing is that the output of your select is a list of rows, with only one value in each row. Try this:

for row in res:
   stainless_getlist.append( row[0] )

The 1st row is tuple containing one string ('304',) not just a string '304'.

answered Mar 16, 2019 at 0:11

Bob McCormick

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