python-3.x – 在Python 3中没有显式打开文件时,将字节转换为字符串

2019年7月28日 253次阅读

我正在使用Requests模块来授权,然后从Web API中提取csv内容,并使其在
Python 2.7中正常运行.我现在想在Python 3.5中编写相同的脚本,但遇到一些问题：

"iterator should return strings, not bytes (did you open the file in text mode?)"

requests.get似乎返回字节而不是字符串,这似乎与转移到Python 3.x时看到的编码问题有关.错误在最后一行的第3行引发：next(读者).在Python 2.7中,这不是问题,因为csv函数是在’wb’模式下处理的.

这篇文章非常相似,但由于我没有直接打开csv文件,我似乎无法强制响应文本以这种方式编码：
csv.Error: iterator should return strings, not bytes

countries = ['UK','US','CA']
datelist = [1,2,3,4]
baseurl = 'https://somewebsite.com/exporttoCSV.php'

#--- For all date/cc combinations
for cc in countries:
    for d in datelist:

        #---Build API String with variables
        url = (baseurl + '?data=chart&output=csv' +
               '&dataset=' + d + 
               '&cc=' + cc)

        #---Run API Call and create reader object
        r = requests.get(url, auth=(username, password))
        text = r.iter_lines()
        reader = csv.reader(text,delimiter=',')

        #---Write csv output to csv file with territory and date columns
        with open(cc + '_'+ d +'.csv','wt', newline='') as file:
            a = csv.writer(file)
            a.writerow(['position','id','title','kind','peers','territory','date']) #---Write header line
            next(reader) #---Skip original headers
            for i in reader:
                a.writerow(i +[countrydict[cc]] + [datevalue])

最佳答案 如果不能测试您的确切场景,我相信这应该通过将text = r.iter_lines()更改为：

text = [line.decode('utf-8') for line in r.iter_lines()]

这应该将r.iter_lines()读入的每一行从字节串解码为csv.reader可用的字符串

我的测试用例如下：

>>> iter_lines = [b'1,2,3,4',b'2,3,4,5',b'3,4,5,6']
>>> text = [line.decode('utf-8') for line in iter_lines]
>>> text
['1,2,3,4', '2,3,4,5', '3,4,5,6']
>>> reader = csv.reader(text,delimiter=',')
>>> next(reader)
['1', '2', '3', '4']
>>> for i in reader:
...     print(i)
...
['2', '3', '4', '5']
['3', '4', '5', '6']
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