Payload.fromJson constructor
Create a new event payload from a JSON Map.
Implementation
factory Payload.fromJson(Map<String, dynamic> json) {
if (json['fields']['query'] != null) return QueryPayload.fromJson(json);
return Payload(
target: json['target'] as String?,
timestamp: json['timestamp'] == null
? null
: DateTime.parse(json['timestamp'] as String),
message: json['fields']['message'].toString(),
);
}