本地变量“服务器”在分配之前引用 [英] local variable 'servers' referenced before assignment

问题描述

db = MySQLdb.connect（localhost，root，aqw，PFE_Project）
cursor = db.cursor（）
sql =SELECT * FROM myform_composantsserveur

try：
cursor.execute（sql）
results = cursor.fetchall（）
currency_in = currency
req = urllib2.urlopen（'http://rate-exchange.appspot.com/currency?from=USD&to=%s'）％（currency_in）
req1 = req.read（）
rate = int（req1 ['rate']）
＃rate = 0.77112893299999996

servers = []
for results in results：
result = {}
result ['1'] = row [1]
result ['3'] = int（row [2]）
result ['4'] = int（row [3]）
result ['5'] = int（row [4]）
result ['6'] = row [5]
result ['7' ] = int（row [6]）
result ['8'] = row [7]
result ['9'] = row [8]
p = rate * calculate_metric（int（row [2]），int（row [3]），int（row [4]），int（row [6]），row [ ）
result ['2'] = p
keys = result.keys（）
keys.sort（）
servers.append（result）

除了：
打印错误：无法获取数据
db.close（）
返回服务器

但编译代码时我有这个错误：

异常类型：UnboundLocalError

异常值：局部变量
'服务器在分配前引用

异常位置：/ home / amine / PFE目录/ mysite1 / myform / Webservice.py在websvc，第43行Python可执行文件：/usr/bin/python2.7

此代码在这个函数中添加参数之前，正常工作

解决方案

您的代码无法到达服务器启动这就是为什么你得到错误。只需在try..except之前移动初始化。改变这种方式：

  def websvc（currency）：
 db = MySQLdb.connect（localhost，root ，aqw，PFE_Project）
 cursor = db.cursor（）
 sql =SELECT * FROM myform_composantsserveur
 servers = [] 
 
 try ：
 cursor.execute（sql）
 results = cursor.fetchall（）
 currency_in = currency 
 req = urllib2.urlopen（'http：//rate-exchange.appspot。 com / currency？from = USD& to =％s'）％（currency_in）
 req1 = req.read（）
 rate = int（req1 ['rate']）
＃rate = 0.77112893299999996 
 
结果中的行：
 result = {} 
 result ['1'] = row [1] 
 result ['3'] = int （row [2]）
 result ['4'] = int（row [3]）
 result ['5'] = int（row [4]）
 result ['6 '] = row [5] 
 result ['7'] = int（row [6]）
 result ['8'] = row [7] 
结果['9'] =行[8] 
p = rate * calculate_metric（int（row [2]），int（row [3]），int（row [4]），int（row [6] ），行[7]）
 result ['2'] = p 
 keys = result.keys（）
 keys.sort（）
 servers.append（result）
 
除了：
打印错误：无法获取数据
 db.close（）
返回服务器
  pre> 
def websvc(currency):
    db = MySQLdb.connect("localhost", "root", "aqw", "PFE_Project")
    cursor = db.cursor()
    sql = "SELECT * FROM myform_composantsserveur"

    try:
        cursor.execute(sql)
        results = cursor.fetchall()
        currency_in = currency
        req = urllib2.urlopen('http://rate-exchange.appspot.com/currency?from=USD&to=%s') % (currency_in) 
        req1 = req.read()
        rate = int(req1['rate'])
        # rate = 0.77112893299999996

        servers = []
        for row in results:
            result = {} 
            result['1'] = row[1]
            result['3'] = int(row[2])
            result['4'] = int(row[3])
            result['5'] = int(row[4])
            result['6'] = row[5]
            result['7'] = int(row[6])
            result['8'] = row[7]
            result['9'] = row[8]
            p = rate * calculations_metric (int(row[2]), int(row[3]), int(row[4]), int(row[6]), row[7])
            result['2'] = p
            keys = result.keys()
            keys.sort()
            servers.append(result)

    except:
        print "Error: unable to fetch data"
    db.close()
    return servers
but i have this error while compiling the code :

  
Exception Type:   UnboundLocalError
  
  
Exception Value:   local variable
  'servers' referenced before assignment 
  
  
Exception Location:   /home/amine/PFE Directory/mysite1/myform/Webservice.py in websvc, line 43 Python Executable:    /usr/bin/python2.7
this code works normally before i added a parameter in this function
解决方案
Your code not able to reach servers initialization and that is why you getting error. Simply move initialization before try..except. Change this way:
def websvc(currency):
    db = MySQLdb.connect("localhost", "root", "aqw", "PFE_Project")
    cursor = db.cursor()
    sql = "SELECT * FROM myform_composantsserveur"
    servers = []

    try:
        cursor.execute(sql)
        results = cursor.fetchall()
        currency_in = currency
        req = urllib2.urlopen('http://rate-exchange.appspot.com/currency?from=USD&to=%s') % (currency_in) 
        req1 = req.read()
        rate = int(req1['rate'])
        # rate = 0.77112893299999996

        for row in results:
            result = {} 
            result['1'] = row[1]
            result['3'] = int(row[2])
            result['4'] = int(row[3])
            result['5'] = int(row[4])
            result['6'] = row[5]
            result['7'] = int(row[6])
            result['8'] = row[7]
            result['9'] = row[8]
            p = rate * calculations_metric (int(row[2]), int(row[3]), int(row[4]), int(row[6]), row[7])
            result['2'] = p
            keys = result.keys()
            keys.sort()
            servers.append(result)

    except:
        print "Error: unable to fetch data"
    db.close()
    return servers


                        
这篇关于本地变量“服务器”在分配之前引用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！