Stringify JSON in Logic App - json

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.
I have my JSON object as an output of a compose
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)
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