python - How to extract a single value from JSON response?

Question

First off, I will freely concede to being little more than a clumsy liberal arts guy who is completely self taught in this scripting thing. That said, I am attempting to get values from a the USGS Water Data Service using the code below:

def main(gaugeId):

    # import modules
    import urllib2, json

    # create string
    url = "http://waterservices.usgs.gov/nwis/iv/?format=json&sites=" + gaugeId + "&parameterCd=00060,00065"

    # open connection to url
    urlFile = urllib2.urlopen(url)

    # load into local JSON list
    jsonList = json.load(urlFile)

    # extract and return
    # how to get cfs, ft, and zulu time?
    return [cfs, ft, time]

Although I have found some tutorials regarding how to extract the desired values from a JSON response, most are fairly simple. The difficulty I am having is extracting from what looks like a very complicated response this service is returning. Looking through the response, I can see what I want is the value from two different sections and a time value. Hence, I can look at the response and see what I need, I just cannot, for the life of me, figure out how to get these values extracted.

Answer 1

using json.loads will turn your data into a python dictionary.

Dictionaries values are accessed using ['key']

resp_str = {
  "name" : "ns1:timeSeriesResponseType",
  "declaredType" : "org.cuahsi.waterml.TimeSeriesResponseType",
  "scope" : "javax.xml.bind.JAXBElement$GlobalScope",
  "value" : {
    "queryInfo" : {
      "creationTime" : 1349724919000,
      "queryURL" : "http://waterservices.usgs.gov/nwis/iv/",
      "criteria" : {
        "locationParam" : "[ALL:103232434]",
        "variableParam" : "[00060, 00065]"
      },
      "note" : [ {
        "value" : "[ALL:103232434]",
        "title" : "filter:sites"
      }, {
        "value" : "[mode=LATEST, modifiedSince=null]",
        "title" : "filter:timeRange"
      }, {
        "value" : "sdas01",
        "title" : "server"
      } ]
    }
  },
  "nil" : false,
  "globalScope" : true,
  "typeSubstituted" : false
}

would translate into a python diction

resp_dict = json.loads(resp_str)

resp_dict['name'] # "ns1:timeSeriesResponseType"

resp_dict['value']['queryInfo']['creationTime'] # 1349724919000