Tc3JsonXmlSampleJsonSaxWriter
Sample of the creation of JSON documents via SAX Writer
This sample illustrates how a JSON message can be created over the DAX mechanism. The function block FB_JsonSaxWriter is used as the basis.
Declaration range
PROGRAM MAIN
VAR
dtTimestamp : DATE_AND_TIME := DT#2017-04-04-12:42:42;
fbJson : FB_JsonSaxWriter;
sJsonDoc : STRING(255);
END_VAR
Implementation range
The SAX mechanism runs sequentially through the JSON document to be created, i.e. the corresponding elements are run though and created one after the other.
fbJson.StartObject();
fbJson.AddKey('Timestamp');
fbJson.AddDateTime(dtTimestamp);
fbJson.AddKey('Values');
fbJson.StartObject();
fbJson.AddKey('Sensor1');
fbJson.AddReal(42.42);
fbJson.AddKey('Sensor2');
fbJson.AddDint(42);
fbJson.AddKey('Sensor3');
fbJson.AddBool(TRUE);
fbJson.EndObject();
fbJson.EndObject();
sJsonDoc := fbJson.GetDocument();
fbJson.ResetDocument();
Resulting JSON message
{
"Timestamp": "2017-04-04T12:42:42",
"Values": {
"Sensor1": 42.42,
"Sensor2": 42,
"Sensor3": true
}
}