Question

我在下面有一个python脚本，它会加载一个yaml文件。参数作为列表传入，因此我可以遍历它们以向字典添加值。下面的代码添加了参数，但json没有正确格式化，如当前和所需的json结果中所示。任何正确方向的帮助表示赞赏。感谢。

YAML档案

  policies:
  - name: ec2age
    resource: ec2
    filters:      
      - State.Name: running
      - "tag:ResourceCreatedBy": present
      - and:
        - type: instance-age
          days: 30
          op: ge

Python脚本：

#!/usr/bin/python
import sys
import argparse
import json
import yaml

parser = argparse.ArgumentParser()
parser.add_argument("-y", "--yaml_file", type=str)
parser.add_argument("-b", "--business_unit", type=str)
parser.add_argument("-p", "--platform", type=str)
parser.add_argument("-c", "--client", type=str)
args = parser.parse_args()

with open(args.yaml_file, 'r') as stream:
    data = yaml.load(stream)

inner_dict = [args.business_unit, args.platform, args.client]

for item in list(inner_dict):
    data['policies'][0]['filters'][0]['tag:BUSINESS_UNIT'] = args.business_unit
    data['policies'][0]['filters'][1]['tag:PLATFORM'] = args.platform

print json.dumps(data)

当前结果：

{
"policies": [
    {
    "resource": "ec2",
    "name": "ec2age",
    "filters": [
        {
        "tag:BUSINESS_UNIT": "TEST_FLITE",
        "State.Name": "running"
        },
        {
        "tag:ResourceCreatedBy": "present"
        },
        {
        "and": [
            {
            "type": "instance-age",
            "days": 30,
            "op": "ge"
            }
        ]
        }
    ]
    }
]
}

期望的结果：

{
"policies": [
    {
    "resource": "ec2",
    "name": "ec2age",
    "filters": [
        {
        "tag:BUSINESS_UNIT": "TEST_FLITE"
        },
        {
        "tag:PLATFORM": "Android"
        },
        {            
        "State.Name": "running"
        },
        {
        "tag:ResourceCreatedBy": "present"
        },
        {
        "and": [
            {
            "type": "instance-age",
            "days": 30,
            "op": "ge"
            }
        ]
        }
    ]
    }
]
}

Answer 1

这部分代码：

inner_dict = [args.business_unit, args.platform, args.client]

for item in list(inner_dict):
    data['policies'][0]['filters'][0]['tag:BUSINESS_UNIT'] = args.business_unit
    data['policies'][0]['filters'][1]['tag:PLATFORM'] = args.platform

并没有多大意义。首先，inner_dict已经是一个列表。我们没有理由再次将其转换为列表 - list(inner_dict)。

其次，在循环中，您迭代3次，对列表中的每个项目迭代一次，并在每个迭代步骤中重复相同的语句。您不会在这些陈述中使用item。

从这里，不知道YAML文件的结构，很难提供解决方案，但你应该寻找上面提到的行。我试着没有循环，只执行：

data['policies'][0]['filters'].append({'tag:BUSINESS_UNIT': args.business_unit})
data['policies'][0]['filters'].append({'tag:PLATFORM': args.platform})

编辑：添加YAML文件内容后，我可以为您提供进一步的解释。致电data['policies'][0]['filters']时，请致电此部分：

[
    {            
        "State.Name": "running"
    },
    {
        "tag:ResourceCreatedBy": "present"
    },
    {
        "and": [
            {
                "type": "instance-age",
                "days": 30,
                "op": "ge"
            }
        ]
    }
]

因此data['policies'][0]['filters'][0]会返回：

{            
    "State.Name": "running"
}

和data['policies'][0]['filters'][0]['tag:BUSINESS_UNIT'] = args.business_unit会为该字典添加新的key：value对：

{            
    "State.Name": "running",
    "tag:BUSINESS_UNIT": "TEST_FLITE"
}

循环没有帮助，它在每个迭代步骤中都是一样的。

我的提议会将所需的键：值对作为字典附加到列表的末尾。如果订单真的很重要，那么你必须改变清单。看看模块collections.deque。

Answer 2

在您的代码中，

inner_dict = [args.business_unit, args.platform, args.client]

for item in list(inner_dict):
    """
      following line appends adds key to 0'th dict which is 
     {
    "tag:BUSINESS_UNIT": "TEST_FLITE",
    "State.Name": "running"
    }
    """
    data['policies'][0]['filters'][0]['tag:BUSINESS_UNIT'] = args.business_unit
    data['policies'][0]['filters'][1]['tag:PLATFORM'] = args.platform

你可以这样做，

#!/usr/bin/python

from __future__ import print_function
import sys
import argparse
import json
import yaml

parser = argparse.ArgumentParser()
parser.add_argument("-y", "--yaml_file", type=str)
parser.add_argument("-b", "--business_unit", type=str)
parser.add_argument("-p", "--platform", type=str)
parser.add_argument("-c", "--client", type=str)
args = parser.parse_args()

with open(args.yaml_file, 'r') as stream:
    data = yaml.load(stream)


inner_list = [{"tag:BUSINESS_UNIT" : args.business_unit},
              {"tag:PLATFORM" : args.platform},
              # {"tag:CLIENT" : args.client} #if needed
             ]

for i, item in enumerate(inner_list):
    data['policies'][0]['filters'].insert(i, item)

print(json.dumps(data))

python字符串到json转换

2 个答案: