Nested Json - Extract Data Policy - apigee

Question

I am having trouble using the "extract data" policy for larger, nested json results. how would I write this in the apigee "extract data" policy? In particular, I'm interessted in the npi, last name, first name and business address fields.
Thanks.
{
"meta": {
"rowCount": 1
},
"result": [
{
"npi": 1671836487,
"type": "individual",
"last_name": "HUTTER",
"first_name": "JOHN",
"name_prefix": "MR.",
"credential": "MD",
"business_address": {
"address_line": "1MAINSTREET",
"city": "HARTFORD",
"state": "CT",
"zip": "06106",
"country_code": "US",
"phone": "8605551212",
"fax": "8605551212"
},
"practice_address": {
"address_line": "1MAINST",
"city": "HARTFORD",
"state": "CT",
"zip": "06106",
"country_code": "US",
"phone": "8605551212",
"fax": "8605551212"
},
"enumeration_date": "2013-04-03T00: 00: 00.000Z",
"last_update_date": "2013-04-03T00: 00: 00.000Z",
"gender": "male",
"provider_details": [
{
"healthcare_taxonomy_code": "101Y00000X",
"license_number": "002295",
"taxonomy_switch": "yes"
}
],
"sole_proprietor": "no"
}
]
}

Answer 1

Make sure your content-type header is set to application/json so the JSONPath option in the ExtractVariable policy works.
Here's a sample policy to extract the above (verified in my own system):
<ExtractVariables async="false" continueOnError="false" enabled="true" name="Extract-Variables-1">
<DisplayName>Extract Variables 1</DisplayName>
<FaultRules/>
<Properties/>
<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
<JSONPayload>
<Variable name="result">
<JSONPath>$.result</JSONPath>
</Variable>
<Variable name="npi">
<JSONPath>$.result[0].npi</JSONPath>
</Variable>
<Variable name="last_name">
<JSONPath>$.result[0].last_name</JSONPath>
</Variable>
<Variable name="first_name">
<JSONPath>$.result[0].first_name</JSONPath>
</Variable>
</JSONPayload>
<Source clearPayload="false">request</Source>
<VariablePrefix>json</VariablePrefix>
</ExtractVariables>
And a sample AssignMessage policy to help you troubleshooting. If you add this to a proxy with no target it'll send back a simple response with the extracted values:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<AssignMessage async="false" continueOnError="false" enabled="true" name="Assign-Message-1">
<DisplayName>Assign Message 1</DisplayName>
<FaultRules/>
<Properties/>
<Set>
<Payload>
npi={json.npi},
last_name={json.last_name},
first_name={json.first_name}
</Payload>
</Set>
<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
<AssignTo createNew="false" transport="http" type="response"/>
</AssignMessage>
Sample response from the above:
npi=1671836487,
last_name=HUTTER,
first_name=JOHN
references:
http://apigee.com/docs/api-services/content/extract-message-content-using-extractvariables
http://apigee.com/docs/api-services/content/generate-or-modify-messages-using-assignmessage

Answer 2

You should be able to do this (I didn't test it):
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ExtractVariables async="false" continueOnError="false" enabled="true" name="get-ressults">
<DisplayName>Get Results</DisplayName>
<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
<JSONPayload>
<Variable name="npi">
$.result[*].npi
</Variable>
<Variable name="first_name">
$.result[*].first_name
</Variable>
<!-- etc. -->
</JSONPayload>
<Source>response</Source>
<VariablePrefix>results</VariablePrefix>
</ExtractVariables>