Currently getting an error TypeError: can only concatenate str (not "NoneType") to str

Question

Traceback (most recent call last):  
  File "<ipython-input-21-0cdf2cfacf71>", line 335, in <module>  
    + my_value_a  
TypeError: can only concatenate str (not "NoneType") to str

谁能帮忙解决这个错误？

代码

def get_env_var(i):
    try:
        letter = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L'][i // 50]
        return os.getenv("MY_VAR_" + letter)
    except IndexError:
        return "demo"


for i in range(0, len(mySymbols)):
    try:
        my_value_a = get_env_var(i)
        #my_value_a = "demo"
        #my_value_a =  os.getenv("MY_VAR_K")
        url_is_y = (
            "https://financialmodelingprep.com/api/v3/financials/income-statement/"
            + mySymbols[i]
            + "?apikey="
            + my_value_a
        )
        url_bs_y = (

Answer 1

因此，如果 os.getenv() 的键无效，则它 return 是您作为第二个参数传递的默认值。如果您不设置此默认值，它将 return 变成 None。可能的修复：

def get_env_var(i):
    try:
        letter = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L'][i // 50]
        return os.getenv("MY_VAR_" + letter, "demo")
    except IndexError:
        return "demo"

如果遇到无效键，这将 return“演示”字符串。或者，如果输出可以接受，您可以这样做：

for i in range(0, len(mySymbols)):
    try:
        my_value_a = get_env_var(i)
        #my_value_a = "demo"
        #my_value_a =  os.getenv("MY_VAR_K")
        url_is_y = (
            "https://financialmodelingprep.com/api/v3/financials/income-statement/"
            + mySymbols[i]
            + "?apikey="
            + str(my_value_a) # This will convert None to 'None'
        )
        url_bs_y = (

查看 this 页面以获取有关此功能如何工作的更多信息和示例。

Answer 2

我建议使用最新的 URL:

"https://financialmodelingprep.com/api/v3/income-statement/"

其中没有“财务”部分。

Currently getting an error TypeError: can only concatenate str (not "NoneType") to str

Currently getting an error TypeError: can only concatenate str (not "NoneType") to str

python

python-3.x

google-colaboratory