not being able to add dynamic expression to .json - azure-data-factory

Question

do you see why I see the error when using the #guid() inside the below .json in the web activity of data factory
[
{
"id":#{guid()}
, "subject": "data/company"
, "topic": null, "eventType": "statusupdated"
, "eventTime": "2022-07-26T09:41:00.9584103Z", "data": { "firstName": "testname", "salary": "test" }, "dataVersion": "1.0", "metadataVersion": null
}
]
error when debug is run:
{"error":{"code":"InvalidRequestContent","message":"The request content is not valid and could not be deserialized: 'Unexpected character encountered while parsing value: b. Path '[0].id', line 2, position 5.'."}}

Answer 1

As the error message The request content is not valid and could not be deserialized: 'Unexpected character encountered while parsing value: b. Path '[0].id', line 2, position 5 indicates, the issue is with the content.
While parsing the JSON, it encountered an unexpected character. This is because of the value of the key id that is #{guid()}. You can validate the json using this third-party validator which indicates the same.
The main issue is the incorrect usage of String Interpolation (#{...}). This feature is used when we need to utilize pipeline expressions inside a string.
But here you have used it directly inside a json as a value for key (id). You can try correcting this by enclosing #{guid()} inside Double quotes ("") to make it a valid JSON (can be checked using the above third-party validator) as shown below:
[
{ "id": "#{guid()}" , "subject": "data/company" , "topic": null, "eventType": "statusupdated" , "eventTime": "2022-07-26T09:41:00.9584103Z", "data": { "firstName": "testname", "salary": "test" }, "dataVersion": "1.0", "metadataVersion": null }
]