Check for json key or object property in mule - json

Question

Scenario - I have to iterate over this payload, and for those listings with error I would need to increment count. But how to check if error property exists?
{
"jobGuid": "123",
"status": "COMPLETED",
"listings": [
{
"exteralListingId": 7654320
},
{
"exteralListingId": 7654321,
"error": {
"code": "inventory.listings.sellerCreditCardNotfound",
"description": "Seller credit card not found"
}
}
]
}
Option1 - Check using json syntax
Option2 - Iterating in a for-each loop over listings, checked for #[payload.error !=null]. But it gave error - Message payload is of type: LinkedHashMap

Answer 1

You can use jsonPath something like xpath but for JSON
I attached my example with the json provided. As you can see there are #[json:listings] which return array, this array will be iterated by foreach and then validate if contains error tag using #[json:error]. errorCount variable store the number of errors and it will be printed in the console.
<http:listener-config name="HTTP_Listener_Configuration" host="0.0.0.0" port="8081" doc:name="HTTP Listener Configuration"/>
<flow name="demoFlow">
<http:listener config-ref="HTTP_Listener_Configuration" path="/" doc:name="HTTP"/>
<set-payload value="{"jobGuid":"123","status":"COMPLETED","listings":[{"exteralListingId":7654320},{"exteralListingId":7654321,"error":{"code":"inventory.listings.sellerCreditCardNotfound","description":"Seller credit card not found"}},{"exteralListingId":7654321,"error":{"code":"inventory.listings.sellerCreditCardNotfound","description":"Seller credit card not found"}},{"exteralListingId":7654321,"error":{"code":"inventory.listings.sellerCreditCardNotfound","description":"Seller credit card not found"}}]}" doc:name="Set Payload"/>
<expression-transformer expression="#[json:listings]" doc:name="Expression"/>
<set-variable variableName="errorCount" value="#[0]" doc:name="Variable"/>
<foreach collection="#[message.payload]" doc:name="For Each">
<expression-filter expression="#[json:error]" doc:name="Expression"/>
<set-variable variableName="errorCount" value="#[flowVars.errorCount + 1 ]" doc:name="Variable"/>
<logger message="counter: #[errorCount]" level="INFO" doc:name="Logger"/>
</foreach>
</flow>
For more information check the official documentation at mule .
http://www.mulesoft.org/documentation/display/current/JSON+Module+Reference