Stringify JSON in Logic App

Question

We are sending messages to a service bus using a logic app. These messages will later be consumed by another service, the service expects the message content to be a string - essentially a stringified JSON object, with escape characters.

We are not able to find a method to stringify a JSON object in Logic Apps. Even if we explicitly provide a escaped string the logic app itself detects that it's stringified JSON and unescapes it and then sends it as a JSON object. We don't want that, we simply want it to send the string as it is. We have already tried changing the content type to text/plain, it does not work. The logic app always sends the unescaped string as JSON.

This post on MSDN: https://social.msdn.microsoft.com/Forums/office/en-US/e5dee958-09a7-4784-b1bf-facdd6b8a568/post-json-from-logic-app-how-to-escape-data?forum=azurelogicapps is of no help because doing this will violate the request contract of the message consuming service

Answer 1

Do you need the stringified message to include opening and closing double quotes?

I've tried this and it worked for me.

1. I have my JSON object as an output of a compose
2. Then, I initialised a variable with the Base64 encoded value of the escaped stringified JSON (you need to add ALL the proper escaping required, mine was just a PoC)

3. Then, you send the variable already in Base64 to Service Bus. (You need to remove the encoding on that action).

   "actions": {
       "Compose_JSON_Object": {
           "inputs": {
               "message": "I want this as a string"
           },
           "runAfter": {},
           "type": "Compose"
       },
       "Initialise_Variable_with_Stringified_JSON_Base64_Encoded": {
           "inputs": {
               "variables": [
                   {
                       "name": "jsonAsStringBase64",
                       "type": "String",
                       "value": "@base64(concat('\"', replace(string(outputs('Compose_JSON_Object')), '\"', '\\\"'), '\"'))"
                   }
               ]
           },
           "runAfter": {
               "Compose_JSON_Object": [
                   "Succeeded"
               ]
           },
           "type": "InitializeVariable"
       },
       "Send_message": {
           "inputs": {
               "body": {
                   "ContentData": "@variables('jsonAsStringBase64')",
                   "ContentType": "text/plain"
               },
               "host": {
                   "connection": {
                       "name": "@parameters('$connections')['servicebus']['connectionId']"
                   }
               },
               "method": "post",
               "path": "/@{encodeURIComponent(encodeURIComponent('temp'))}/messages",
               "queries": {
                   "systemProperties": "None"
               }
           },
           "runAfter": {
               "Initialise_Variable_with_Stringified_JSON_Base64_Encoded": [
                   "Succeeded"
               ]
           },
           "type": "ApiConnection"
       }
   },
   

This way, I got the message stringified.

HTH