I want to filter some fields from json file

Google Cloud Apigee
1 
	"altitude":"444.0","heading":"230.0","timestamplocal":"2018-12-07 18:37:24","fuelLevel":"359.04","location":"Srinagar - Kanyakumari Hwy,

I want to get only the following fields

vehicle_number,latitude,longitude,speed,distance,datetime

Please suggest me how can i go about it..

2

From 15 fields i want to filter only 5 fields

3

Hi Hima, you need to provide more info like,

  • will you get JSON in request/response?
  • when you say filter, what do you want to do with the filtered fields?
    • form another JSON?
  • provide a valid JSON for better suggestions

The below example is based on the assumptions, JSON is received in Request and the filtered fields needs to be formed as a JSON, this can be done in multiple ways,

JSON coming in Request,

{
  "altitude": "444.0",
  "heading": "230.0",
  "timestamplocal": "2018-12-07 18:37:24",
  "fuelLevel": "359.04",
  "location": "Srinagar - Kanyakumari Hwy"
}

Extracting location & fuelLevel fields using Extract Variable policy,

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ExtractVariables async="false" continueOnError="false" enabled="true" name="Extract-Variables">
    <DisplayName>Extract Variables-1</DisplayName>
    <Properties/>
    <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
    <JSONPayload>
        <Variable name="location">
            <JSONPath>$.location</JSONPath>
        </Variable>
        <Variable name="fuelLevel">
            <JSONPath>$.fuelLevel</JSONPath>
        </Variable>
    </JSONPayload>
    <Source clearPayload="false">request</Source>
    <VariablePrefix>hima</VariablePrefix>
</ExtractVariables>

Forming a JSON payload using Assign Message Policy,

<?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>
    <Set>
        <Payload contentType="application/json">
            {
		"extracted_location":"{hima.location}", 
		"extracted_fuelLevel":"{hima.fuelLevel}"
	    }
        </Payload>
    </Set>
    <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
    <AssignTo createNew="false" transport="http" type="request"/>
</AssignMessage>

The JSON will be available in **message.content** flow variable,

{"extracted_location":"Srinagar - Kanyakumari Hwy", "extracted_fuelLevel":"359.04"}
2 Likes
4

Or if the fields you want are dynamic, you could use a javascript policy where you loop through the array of attributes to filter by to build a new object

newObject[attr] = oldObject[attr]

1 Like
5

How do i input the json in request or respone?

6

and here is a more in-depth description of that technique, with some re-usable JS code.

7

Siddharth, good answer.

Please note, you can also now skip the ExtractVariables policy.

<AssignMessage name='AM-Response'>
  <AssignVariable>
    <Name>json_path_location</Name>
    <Value>$.location</Value>
  </AssignVariable>
  <AssignVariable>
    <Name>json_path_fuelLevel</Name>
    <Value>$.fuelLevel</Value>
  </AssignVariable>
  <Set>
    <Payload contentType='application/json'>{
  "extracted_location":"{jsonPath(json_path_location,request.content)}",
  "extracted_fuelLevel":"{jsonPath(json_path_fuelLevel,request.content)}"
}</Payload>
  </Set>
  <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
  <AssignTo createNew='false' transport='http' type='response'/>
</AssignMessage>
8

Thanks, Dino for the example. I guess it is high time I need to explore Message Templates and start using/suggesting them :slight_smile:

I haven’t tried it, but I guess we can use this AssignMessage on both Request & Response flows right?

Other then request.content, if we are expecting a similar/different JSON fields through ServiceCallout or another AssignMessage before this AssignMessage policy, I guess we need to use calloutResponse.content and message.content respectively.

 <Set>
      <Payload contentType="application/json">
          {
            "serviceCallout":"{jsonPath(json_path_location,calloutResponse.content)}",
            "assignMessage":"{jsonPath(json_path_fuelLevel,message.content)}",
	    "targetResponse":"{jsonPath(json_path_fuelLevel,response.content)}"
          }
      </Payload>
 </Set>
9

If you are making a call to Apigee with Post method and JSON body, then this is a request JSON to APigee.

If the TargetEndpoint in Apigee is giving a JSON response, it is considered as JSON in response phase.

10

Yes, you can use this AssignMessage on both Request & Response flows.

and yes, with the jsonPath() function, you can reference any context variable that contains valid json.