我有一个名为json_dict的字典，如下所示。
我需要访问元素==> json_dict['OptionSettings'][3]['Value']。
我需要使用语法
访问该元素 print(json_dict[parameter])。
当我提供诸如
之类的参数时 param="['OptionSettings'][3]['Value']"或
param="'OptionSettings'][3]['Value']"
我收到如下错误：
KeyError: "['OptionSettings'][3]['Value']"。
我尝试使用以下解决方案，但它只打印了一个字符串
str1="json_dict"
print(str1+param)
下面的完整词典：
{
"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"
}
]
}
答案 0 :(得分：2)
不幸的是你做不到。
当您键入param="['OptionSettings'][3]['Value']"然后json_dict[param]时，您基本上要求键"['OptionSettings'][3]['Value']"所代表的值不存在。
你必须浏览关卡才能到达最后一层。
但是，当然，如果您需要单行，您可以随时创建一些逻辑并将其提取到方法中。
例如，而不是
print(json_dict[param]).
你可以使用像
这样的东西print(get_json_value(json_dict, param))
并定义一个函数，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
for elem in list_of_params:
_ = _[elem]
return _
我没有测试过，但它应该可以正常工作。
（此外，它只是一个演示来指导您完成备用解决方案）
答案 1 :(得分：-1)
这对我有用
str1="json_dict"
params="['OptionSettings'][3]['Value']"
str2=str1+params
print(eval(str5))
此处使用函数 eval（） 是解决此问题的关键。