从 Json 中提取

Question

From one of the method i am getting below output

        {'Records': [{'messageId': '2953dfd5-d848-42b2-a60b-43df00ec8e5f', 
       'receiptHandle': 'AQEBPMr5RbW3T2DG4pAYi+', 'body': 
      'I am still trying', 'attributes': {'ApproximateReceiveCount': '1', 
        'SentTimestamp': '1552073955807', 'SenderId': '944198216610', 
        'ApproximateFirstReceiveTimestamp': '1552073955816'}, 
        'messageAttributes': {}, 'md5OfBody': 
         '2111a742ddbdac2d862fa6a204f7dc85', 'eventSource': 'aws:sqs', 
          'eventSourceARN': 'arn:aws:sqs:us-east- 
         1:944198216610:LambadaQueue', 'awsRegion': 'us-east-1'}]}

Now i want to fetch the value of body from this so i have used below

body=event['Records'][0][0]['body']

But this is not working.Can you please help me figure out what wrong i am doing?

Answer 1

What am I doing wrong?

The Records key is a list and you can select items from a list using the index number for that item.

json_string = {
              "Records": [
    {
      "messageId": "2953dfd5-d848-42b2-a60b-43df00ec8e5f",
      "receiptHandle": "AQEBPMr5RbW3T2DG4pAYi+",
      "body": "I am still trying",
      "attributes": {
        "ApproximateReceiveCount": "1",
        "SentTimestamp": "1552073955807",
        "SenderId": "944198216610",
        "ApproximateFirstReceiveTimestamp": "1552073955816"
      },
      "messageAttributes": { },
      "md5OfBody": "2111a742ddbdac2d862fa6a204f7dc85",
      "eventSource": "aws:sqs",
      "eventSourceARN": "arn:aws:sqs:us-east-1:944198216610: LambadaQueue",
      "awsRegion": "us-east-1"
    }
  ]
}

So, when you do json_string['Records'][0] , this selects the first item in the list which is again a dictionary:

{
  "messageId": "2953dfd5-d848-42b2-a60b-43df00ec8e5f",
  "receiptHandle": "AQEBPMr5RbW3T2DG4pAYi+",
  "body": "I am still trying",
 ....}

Now if you do json_string['Records'][0][0] , you are trying to access a dictionary key like an item in a list(using index number 0) which is syntacticaly incorrect. You can access the key by name such as json_string['Records'][0]['messageId'] if you want to access the value for 'messageId', or as in your question, the "body" key's value like this:

`json_string['Records'][0]['body']`

 #Output:
 I am still trying

Answer 2

Are you trying to get 'I am still trying'?

json_data = {
  'Records': [{
    'messageId': '2953dfd5-d848-42b2-a60b-43df00ec8e5f',
    'receiptHandle': 'AQEBPMr5RbW3T2DG4pAYi+',
    'body': 'I am still trying',
    'attributes': {
        'ApproximateReceiveCount': '1',
        'SentTimestamp': '1552073955807',
        'SenderId': '944198216610',
        'ApproximateFirstReceiveTimestamp': '1552073955816'
    },
    'messageAttributes': {},
    'md5OfBody': '2111a742ddbdac2d862fa6a204f7dc85',
    'eventSource': 'aws:sqs',
    'eventSourceARN': 'arn:aws:sqs:us-east-1: 944198216610: LambadaQueue',
    'awsRegion': 'us - east - 1'
  }]
}

print (json_data['Records'][0]['body'])
# output
# I am still trying

Answer 3

If you're attempting to get the value of the "body" element, it looks like you should just skip the second [0] in your lookup. Properly formatted, it looks like this:

{
  "Records": [
    {
      "messageId": "2953dfd5-d848-42b2-a60b-43df00ec8e5f",
      "receiptHandle": "AQEBPMr5RbW3T2DG4pAYi+",
      "body": "I am still trying",
      "attributes": {
        "ApproximateReceiveCount": "1",
        "SentTimestamp": "1552073955807",
        "SenderId": "944198216610",
        "ApproximateFirstReceiveTimestamp": "1552073955816"
      },
      "messageAttributes": { },
      "md5OfBody": "2111a742ddbdac2d862fa6a204f7dc85",
      "eventSource": "aws:sqs",
      "eventSourceARN": "arn:aws:sqs:us-east-1:944198216610: LambadaQueue",
      "awsRegion": "us-east-1"
    }
  ]
}

So, to get the value of the field "body" for the first record in "Records", it looks like you should do: body=event['Records'][0]['body']