How can I save entire message fields in the Alert Action Setting- OpenSearch

{
“level”: “Error”,
“messageTemplate”: “”,
“message”: “”,
“fields”: {
“Message”: {
“SimplifiedMessage”: “”,
“StackTrace”: “”,
“Data”: “”
},
“Context”: {
“Business”: “”,
“Domain”: “”,
“CorrelationId”: “”,
“Environment”: “”,
“UserName”: “”,
“TenantId”: “”,
“ChargingStationId”: “”,
“Method”: “”,
“Action”: “”,
“TimeStamp”: “”,
“Module”: “”
}
}
}
this is format of message so, I want to save in text file, after trigger hit,

Monitor {{ctx.monitor.name}} just entered an alert state. Please investigate the issue.

  • Trigger: {{ctx.trigger.name}}
  • Severity: {{ctx.trigger.severity}}
  • Period start: {{ctx.periodStart}}
  • Period end: {{ctx.periodEnd}} this is action section default setting, How should i modify this, please help me.
    Thank you