KeyError访问字典? [英] KeyError while accessing dictionary?
问题描述
我在下面给出一个名为 json_dict
的字典。
我需要访问元素 ==> json_dict ['OptionSettings'] [3] ['Value']
。
我需要使用语法访问元素
print(json_dict [parameter])
。
当我给出一个参数,如
param =['OptionSettings' ] [3] ['Value']
或
param ='OptionSettings'] [3] 'Value']
我收到如下错误:
KeyError:['OptionSettings'] [3] ['Value']
。
使用以下解决方案,但它只是打印一个字符串
str1 =json_dict
print(str1 + param)
完整词典如下:
{
/ pre>
ApplicationName:Test,
EnvironmentName:ABC-Nodejs,
CNAMEPrefix:ABC-Neptune,
SolutionStackName:64bit Amazon Linux 2016.03 v2.1.1运行Node.js,
OptionSettings:[
{
命名空间:aws:ec2:vpc
OptionName:AssociatePublicIpAddr ess,
Value:true
},
{
Namespace:aws:elasticbeanstalk:environment,
OptionName
Value:LoadBalanced
},
{
命名空间:aws:ec2:vpc,
OptionName子网,
值:param1
},
{
命名空间:aws:autoscaling:launchconfiguration,
OptionName安全组,
值:param2
},
{
命名空间:aws:autoscaling:asg,
OptionName:MinSize,
Value:1
},
{
命名空间:aws:autoscaling:asg,
OptionName:MaxSize,
Value:4
},
{
命名空间:aws:autoscaling:asg,
OptionName:可用区域,
值:任何
},
{
命名空间:aws:autoscaling:asg,
OptionName:冷却,
值:360
},
{
命名空间:aws:autoscaling:launchconfiguration,
OptionName:IamInstanceProfile,
Value:NepRole
},
{
命名空间:aws:autoscaling:launchconfiguration,
OptionName:MonitoringInterval,
Value:5分钟
},
{
命名空间:aws:autoscaling:launchconfiguration,
OptionName:RootVolumeType,
Value:gp2
},
{
命名空间:aws:autoscaling:launchconfiguration,
选项名称:RootVolumeSize,
值:10
},
{
namespace:aws:elasticbeanstalk:sns:topics,
OptionName:Notification Endpoint,
Value:sunil.kumar2@pb.com
}
{
命名空间:aws:elasticbeanstalk:hostmanager,
OptionName:LogPublicationControl,
Value:false
}
{
Namespace:aws:elasticbeanstalk:command,
OptionName:DeploymentPolicy,
Value:滚动
}
{
命名空间:aws:elasticbeanstalk:command,
OptionName:BatchSizeType,
Value 百分比
},
{
命名空间:aws:elasticbeanstalk:command,
OptionName:BatchSize,
Value 100
},
{
命名空间:aws:elasticbeanstalk:command,
OptionName:HealthCheckSuccessThreshold,
Value OK
},
{
命名空间:aws:elasticbeanstalk:command,
OptionName:IgnoreHealthCheck,
Value false
},
{
命名空间:aws:elasticbeanstalk:command,
OptionName :超时,
值:600
},
{
命名空间:aws:autoscaling:updatepolicy:rollingupdate,
OptionName:RollingUpdateEnabled,
Value:false
},
{
命名空间:aws:ec2:vpc,
OptionName:ELBSubnets,
Value:param3
},
{
命名空间:aws:elb:loadbalancer,
OptionName:SecurityGroups,
Value:param4
},
{
命名空间:aws:elb:loadbalancer,
OptionName:ManagedSecurityGroup,
Value:param4
}
]
}
解决方案不幸的是你不能这样做。
当您键入
param =['OptionSettings'] [3] ['Value']
然后json_dict [param]
,您基本上是要求由密钥表示的值['OptionSettings'] [3] ['Value']
不存在。
您必须浏览级别才能到达最后一级。
但当然,如果您需要一个单行,您可以随时创建一些逻辑并将其解压缩到方法。
例如,而不是
print(json_dict [ PARAM])。
你可以使用像
print(get_json_value(json_dict,param))
并定义一个函数例如
import re
def get_json_value(json_dict,params):
list_of_params = re.findall(r'\ [([^]] *)\]',params)
#list_of_params = ['OptionSettings','3','Value']
_ = json_dict
在list_of_params中的elem:
_ = _ [elem]
return _
我没有测试,但它应该可以正常工作。
(另外,这只是一个引导您完成替代解决方案的演示)I have a dictionary named
json_dict
given below.I need to access the element
==> json_dict['OptionSettings'][3]['Value']
.I need to access the element using the syntax
print(json_dict[parameter])
.When I give a parameter such as
param="['OptionSettings'][3]['Value']"
or
param="'OptionSettings'][3]['Value']"
I am getting an error like the one below:
KeyError: "['OptionSettings'][3]['Value']"
.I tried to use the below solution but it just printed a string
str1="json_dict" print(str1+param)
Full Dictionary below:
{ "ApplicationName": "Test", "EnvironmentName": "ABC-Nodejs", "CNAMEPrefix": "ABC-Neptune", "SolutionStackName": "64bit Amazon Linux 2016.03 v2.1.1 running Node.js", "OptionSettings": [ { "Namespace": "aws:ec2:vpc", "OptionName": "AssociatePublicIpAddress", "Value": "true" }, { "Namespace": "aws:elasticbeanstalk:environment", "OptionName": "EnvironmentType", "Value": "LoadBalanced" }, { "Namespace": "aws:ec2:vpc", "OptionName": "Subnets", "Value": "param1" }, { "Namespace": "aws:autoscaling:launchconfiguration", "OptionName": "SecurityGroups", "Value": "param2" }, { "Namespace": "aws:autoscaling:asg", "OptionName": "MinSize", "Value": "1" }, { "Namespace": "aws:autoscaling:asg", "OptionName": "MaxSize", "Value": "4" }, { "Namespace": "aws:autoscaling:asg", "OptionName": "Availability Zones", "Value": "Any" }, { "Namespace": "aws:autoscaling:asg", "OptionName": "Cooldown", "Value": "360" }, { "Namespace": "aws:autoscaling:launchconfiguration", "OptionName": "IamInstanceProfile", "Value": "NepRole" }, { "Namespace": "aws:autoscaling:launchconfiguration", "OptionName": "MonitoringInterval", "Value": "5 minutes" }, { "Namespace": "aws:autoscaling:launchconfiguration", "OptionName": "RootVolumeType", "Value": "gp2" }, { "Namespace": "aws:autoscaling:launchconfiguration", "OptionName": "RootVolumeSize", "Value": "10" }, { "Namespace": "aws:elasticbeanstalk:sns:topics", "OptionName": "Notification Endpoint", "Value": "sunil.kumar2@pb.com" }, { "Namespace": "aws:elasticbeanstalk:hostmanager", "OptionName": "LogPublicationControl", "Value": "false" }, { "Namespace": "aws:elasticbeanstalk:command", "OptionName": "DeploymentPolicy", "Value": "Rolling" }, { "Namespace": "aws:elasticbeanstalk:command", "OptionName": "BatchSizeType", "Value": "Percentage" }, { "Namespace": "aws:elasticbeanstalk:command", "OptionName": "BatchSize", "Value": "100" }, { "Namespace": "aws:elasticbeanstalk:command", "OptionName": "HealthCheckSuccessThreshold", "Value": "Ok" }, { "Namespace": "aws:elasticbeanstalk:command", "OptionName": "IgnoreHealthCheck", "Value": "false" }, { "Namespace": "aws:elasticbeanstalk:command", "OptionName": "Timeout", "Value": "600" }, { "Namespace": "aws:autoscaling:updatepolicy:rollingupdate", "OptionName": "RollingUpdateEnabled", "Value": "false" }, { "Namespace": "aws:ec2:vpc", "OptionName": "ELBSubnets", "Value": "param3" }, { "Namespace": "aws:elb:loadbalancer", "OptionName": "SecurityGroups", "Value": "param4" }, { "Namespace": "aws:elb:loadbalancer", "OptionName": "ManagedSecurityGroup", "Value": "param4" } ] }
解决方案Unfortunately you can't do that.
When you type
param="['OptionSettings'][3]['Value']"
and thenjson_dict[param]
, you are basically asking for the value represented by the key"['OptionSettings'][3]['Value']"
which does not exists.You´ll have to navigate through the levels until you get to the last one.
But of course, if you need a one-liner, you can always create some logic and extract that to a method.
For example, instead of
print(json_dict[param]).
you could use something like
print(get_json_value(json_dict, param))
and define a function such as
import re def get_json_value(json_dict, params): list_of_params = re.findall(r'\[([^]]*)\]', params) #list_of_params = ['OptionSettings', '3', 'Value'] _ = json_dict for elem in list_of_params: _ = _[elem] return _
I haven't tested it but it should work fine.
(Also, it is just a demo made to guide you through an alternate solution)这篇关于KeyError访问字典?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!