Python 未绑定本地错误不会持续发生

我试图将数据添加到我的SQlite3表中，该表运行在一个函数上，该函数使用两个参数来查找一个城市和一个街区

def scrapecafes（city，area）

奇怪的是，这对我输入的一些参数很有效，但对其他参数无效。例如，如果我运行

scrapecafes（墨尔本，桑伯里）

代码工作正常，但是如果我运行

scrapecafes（墨尔本，卡尔顿）

我会得到以下错误：

UnboundLocalError:赋值前引用的局部变量“lat”

我知道该函数肯定能工作，但我不明白为什么某些参数会出现UnboundLocalError，而其他参数则不会。下面是代码：

import folium
from bs4 import BeautifulSoup
import requests
from requests import get
import sqlite3
import geopandas
import geopy
from geopy.geocoders import Nominatim
from geopy.extra.rate_limiter import RateLimiter

#cafeNames
def scrapecafes(city, area):

    #url = 'https://www.broadsheet.com.au/melbourne/guides/best-cafes-thornbury' #go to the website
    url = f"https://www.broadsheet.com.au/{city}/guides/best-cafes-{area}"
    response = requests.get(url, timeout=5)

    soup_cafe_names = BeautifulSoup(response.content, "html.parser")
    type(soup_cafe_names)

    cafeNames = soup_cafe_names.findAll('h2', attrs={"class":"venue-title", }) #scrape the elements
    cafeNamesClean = [cafe.text.strip() for cafe in cafeNames] #clean the elements
    #cafeNameTuple = [(cafe,) for cafe in cafeNamesCleans

    #print(cafeNamesClean)

    #addresses
    soup_cafe_addresses = BeautifulSoup(response.content, "html.parser")
    type(soup_cafe_addresses)

    cafeAddresses = soup_cafe_addresses.findAll( attrs={"class":"address-content" })
    cafeAddressesClean = [address.text for address in cafeAddresses]
    #cafeAddressesTuple = [(address,) for address in cafeAddressesClean]

    #print(cafeAddressesClean)

    ##geocode addresses
    locator = Nominatim(user_agent="myGeocoder")
    geocode = RateLimiter(locator.geocode, min_delay_seconds=1)

    try:
        location = []
        for item in cafeAddressesClean:
            location.append(locator.geocode(item))

            lat = [loc.latitude for loc in location]
            long = [loc.longitude for loc in location]
    except:
        pass


    #zip up for table
    fortable = list(zip(cafeNamesClean, cafeAddressesClean, lat, long))
    print(fortable)
    
##connect to database
    try:
        sqliteConnection = sqlite3.connect('25july_database.db')
        cursor = sqliteConnection.cursor()
        print("Database created and Successfully Connected to 25july_database")

        sqlite_select_Query = "select sqlite_version();"
        cursor.execute(sqlite_select_Query)
        record = cursor.fetchall()
        print("SQLite Database Version is: ", record)
        cursor.close()

    except sqlite3.Error as error:
        print("Error while connecting to sqlite", error)

    #create table
    try:
        sqlite_create_table_query = ''' CREATE TABLE IF NOT EXISTS test555 (
                                        name TEXT NOT NULL,
                                        address TEXT NOT NULL,
                                        latitude FLOAT NOT NULL,
                                        longitude FLOAT NOT NULL
                                        );'''

        cursor = sqliteConnection.cursor()
        print("Successfully Connected to SQLite")
        cursor.execute(sqlite_create_table_query)
        sqliteConnection.commit()
        print("SQLite table created")

    except sqlite3.Error as error:
        print("Error while creating a sqlite table", error)

##enter data into table
    try:
        sqlite_insert_name_param = """INSERT INTO test555
                            (name, address, latitude, longitude)
                            VALUES (?,?,?,?);"""

        cursor.executemany(sqlite_insert_name_param, fortable)

        sqliteConnection.commit()
        print("Total", cursor.rowcount, "Records inserted successfully into table")
        sqliteConnection.commit()

        cursor.close()

    except sqlite3.Error as error:
        print("Failed to insert data into sqlite table", error)

    finally:
        if (sqliteConnection):
            sqliteConnection.close()
            print("The SQLite connection is closed")

---

问题是

geopy

没有

Carlton

的坐标。因此，在这种情况下，您应该更改表架构并插入

null

当

geopy

没有数据时，它返回

None

，当尝试调用

None

时，它抛出异常。您必须将

try/except

块放入

for

循环中

from bs4 import BeautifulSoup
import requests
from requests import get
import sqlite3
import geopandas
import geopy
from geopy.geocoders import Nominatim
from geopy.extra.rate_limiter import RateLimiter

#cafeNames
def scrapecafes(city, area):

    #url = 'https://www.broadsheet.com.au/melbourne/guides/best-cafes-thornbury' #go to the website
    url = f"https://www.broadsheet.com.au/{city}/guides/best-cafes-{area}"
    response = requests.get(url, timeout=5)

    soup_cafe_names = BeautifulSoup(response.content, "html.parser")

    cafeNames = soup_cafe_names.findAll('h2', attrs={"class":"venue-title", }) #scrape the elements
    cafeNamesClean = [cafe.text.strip() for cafe in cafeNames] #clean the elements
    #cafeNameTuple = [(cafe,) for cafe in cafeNamesCleans

    #addresses
    soup_cafe_addresses = BeautifulSoup(response.content, "html.parser")

    cafeAddresses = soup_cafe_addresses.findAll( attrs={"class":"address-content" })
    cafeAddressesClean = [address.text for address in cafeAddresses]
    #cafeAddressesTuple = [(address,) for address in cafeAddressesClean]

    ##geocode addresses
    locator = Nominatim(user_agent="myGeocoder")
    geocode = RateLimiter(locator.geocode, min_delay_seconds=1)
    lat = []
    long = []
    
    for item in cafeAddressesClean:
        try:
            location = locator.geocode(item.strip().replace(',',''))
            lat.append(location.latitude)
            long.append(location.longitude)
        except:
            lat.append(None)
            long.append(None)

    #zip up for table
    fortable = list(zip(cafeNamesClean, cafeAddressesClean, lat, long))
    print(fortable)
    
##connect to database
    try:
        sqliteConnection = sqlite3.connect('25july_database.db')
        cursor = sqliteConnection.cursor()
        print("Database created and Successfully Connected to 25july_database")

        sqlite_select_Query = "select sqlite_version();"
        cursor.execute(sqlite_select_Query)
        record = cursor.fetchall()
        print("SQLite Database Version is: ", record)
        cursor.close()

    except sqlite3.Error as error:
        print("Error while connecting to sqlite", error)

    #create table
    try:
        sqlite_create_table_query = ''' CREATE TABLE IF NOT EXISTS test (
                                        name TEXT NOT NULL,
                                        address TEXT NOT NULL,
                                        latitude FLOAT,
                                        longitude FLOAT
                                        );'''

        cursor = sqliteConnection.cursor()
        print("Successfully Connected to SQLite")
        cursor.execute(sqlite_create_table_query)
        sqliteConnection.commit()
        print("SQLite table created")

    except sqlite3.Error as error:
        print("Error while creating a sqlite table", error)

##enter data into table
    try:
        sqlite_insert_name_param = """INSERT INTO test
                            (name, address, latitude, longitude)
                            VALUES (?,?,?,?);"""

        cursor.executemany(sqlite_insert_name_param, fortable)

        sqliteConnection.commit()
        print("Total", cursor.rowcount, "Records inserted successfully into table")
        sqliteConnection.commit()

        cursor.close()

    except sqlite3.Error as error:
        print("Failed to insert data into sqlite table", error)

    finally:
        if (sqliteConnection):
            sqliteConnection.close()
            print("The SQLite connection is closed")

scrapecafes('melbourne', 'carlton')