如何訪問字典值？

Question

我dict類型的響應語法：

{ 
    'StoppingInstances': [ 
     { 
      'InstanceId': 'string', 
      'CurrentState': { 
       'Code': 123, 
       'Name': 'pending'|'running'|'shutting-down'|'terminated'|'stopping'|'stopped' 
      }, 
      'PreviousState': { 
       'Code': 123, 
       'Name': 'pending'|'running'|'shutting-down'|'terminated'|'stopping'|'stopped' 
      } 
     }, 
    ] 
} 

現在，如果我需要檢查，如果在currentState是stopping怎麼辦呢？

print "Stopping instance Now",response['StoppingInstances'] 

for instance in response['StoppingInstances']: 
    if instance['CurrentState']['Name'] == "stopping": 
     print "Still Stooping" 

    if instance['CurrentState']['Name'] == "stopped": 
     print "Instance Stopped" 
print "Now Starting the instance" 
response_new = client.start_instances(InstanceIds=[instance_id]) 
for start_instance in response_new['StartingInstances']: 
    if start_instance['CurrentState']['Name'] == "running": 
     print "Instance is UP and running" 
    else: 
     print "Some Error occured!!" 

Answer 1

你response['StoppingInstances']對象是字典的列表。你必須要麼環比那些或索引中的單個項目：

response['StoppingInstances'][0]['CurrentState']['Name'] == "stopping" 

如果你需要測試，如果任何這些對象是在stopping狀態，你可以使用any()功能：

any(o['CurrentState']['Name'] == "stopping" for o in response['StoppingInstances']) 

如果你需要測試每個實例，使用循環：

for instance in response['StoppingInstances']: 
    if instance['CurrentState']['Name'] == "stopping": 

Answer 2

你的數據包含封閉歐特列表字典值，而不是簡單的嵌套字典，如你所想。您需要索引列表，然後通過鍵訪問嵌套字典值：

response['StoppingInstances'][0]['CurrentState']['Name'] 
#       ^

而在你if塊：

if response['StoppingInstances'][0]['CurrentState']['Name'] == "stopped": 
    print "Instance Stopped"