> ## Documentation Index > Fetch the complete documentation index at: https://docs.coreflux.org/llms.txt > Use this file to discover all available pages before exploring further. # MODEL Publishing > Create structured data dynamically from actions using COLLAPSED models and PUBLISH MODEL ## When to Use Action Models Action models (COLLAPSED models) are templates for structured data that you publish explicitly from within actions. They're ideal when you need: * **Control over timing** - Publish only when specific conditions are met * **Dynamic routing** - Send data to different topics based on logic * **Data transformation** - Process and enrich data before structuring Unlike basic models that trigger automatically on topic changes, action models let you decide exactly when and where structured data is created. With `WITH FORMAT PROTOBUF`, that output is binary protobuf bytes rather than JSON — see [Protobuf Models](./protobuf). ### Example Use Case Imagine you receive raw alarm data and need to: 1. Extract relevant fields from JSON 2. Add a unique ID and timestamp 3. Route critical alarms to a special topic 4. Publish a structured record ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE MODEL AlarmRecord COLLAPSED ADD STRING "alarm_id" ADD STRING "equipment_id" ADD STRING "severity" ADD STRING "timestamp" DEFINE ACTION ProcessAlarm ON TOPIC "alarms/+/input" DO SET "equipment_id" WITH TOPIC POSITION 2 SET "severity" WITH (GET JSON "severity" IN PAYLOAD AS STRING) PUBLISH MODEL AlarmRecord TO "alarms/structured/" + {equipment_id} WITH alarm_id = (RANDOM UUID) equipment_id = {equipment_id} severity = {severity} timestamp = TIMESTAMP "UTC" IF {severity} EQUALS "CRITICAL" THEN PUBLISH TOPIC "alerts/critical/" + {equipment_id} WITH PAYLOAD ``` *** ## Step-by-Step Guide Create a template with all required fields. The `COLLAPSED` keyword indicates this model has no automatic trigger: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE MODEL SensorRecord COLLAPSED ADD STRING "sensor_id" ADD STRING "sensor_type" ADD DOUBLE "temperature" ADD DOUBLE "humidity" ADD STRING "quality_status" ADD STRING "timestamp" ``` Define an action that extracts data and publishes the model: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE ACTION ProcessSensorJSON ON TOPIC "sensors/+/json_data" DO SET "sensor_id" WITH TOPIC POSITION 2 // Extract from JSON payload SET "temp" WITH (GET JSON "temperature" IN PAYLOAD AS DOUBLE) SET "hum" WITH (GET JSON "humidity" IN PAYLOAD AS DOUBLE) SET "type" WITH (GET JSON "type" IN PAYLOAD AS STRING) SET "quality" WITH (GET JSON "quality" IN PAYLOAD AS STRING) // Publish structured record PUBLISH MODEL SensorRecord TO "sensors/processed/" + {sensor_id} WITH sensor_id = {sensor_id} sensor_type = {type} temperature = {temp} humidity = {hum} quality_status = {quality} timestamp = TIMESTAMP "UTC" ``` **Publish to:** `sensors/temp001/json_data` ```json wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} { "temperature": 23.5, "humidity": 65, "type": "environmental", "quality": "GOOD" } ``` **Result at:** `sensors/processed/temp001` ```json wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} { "sensor_id": "temp001", "sensor_type": "environmental", "temperature": 23.5, "humidity": 65, "quality_status": "GOOD", "timestamp": "2025-10-25T14:30:15Z" } ``` *** ## Use Case Examples Route alarms by severity while creating structured records: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE MODEL AlarmRecord COLLAPSED ADD STRING "alarm_id" ADD STRING "equipment_id" ADD STRING "alarm_type" ADD DOUBLE "trigger_value" ADD STRING "severity" ADD STRING "timestamp" DEFINE ACTION ProcessAlarmJSON ON TOPIC "alarms/+/input" DO SET "equipment_id" WITH TOPIC POSITION 2 PUBLISH MODEL AlarmRecord TO "alarms/structured/" + {equipment_id} WITH alarm_id = (RANDOM UUID) equipment_id = {equipment_id} alarm_type = (GET JSON "type" IN PAYLOAD AS STRING) trigger_value = (GET JSON "value" IN PAYLOAD AS DOUBLE) severity = (GET JSON "severity" IN PAYLOAD AS STRING) timestamp = TIMESTAMP "UTC" // Route critical alarms SET "sev" WITH (GET JSON "severity" IN PAYLOAD AS STRING) IF {sev} EQUALS "CRITICAL" THEN PUBLISH TOPIC "alerts/critical/" + {equipment_id} WITH PAYLOAD ``` Calculate metrics and generate quality reports: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE MODEL QualityReport COLLAPSED ADD STRING "report_id" ADD STRING "station_id" ADD INT "items_tested" ADD INT "items_passed" ADD DOUBLE "pass_rate" ADD STRING "timestamp" DEFINE ACTION GenerateQualityReport ON TOPIC "quality/+/results" DO SET "station" WITH TOPIC POSITION 2 SET "tested" WITH (GET JSON "total" IN PAYLOAD AS INT) SET "passed" WITH (GET JSON "passed" IN PAYLOAD AS INT) SET "rate" WITH ({passed} AS DOUBLE / {tested} AS DOUBLE * 100) PUBLISH MODEL QualityReport TO "reports/quality/" + {station} WITH report_id = (RANDOM UUID) station_id = {station} items_tested = {tested} items_passed = {passed} pass_rate = {rate} timestamp = TIMESTAMP "UTC" IF {rate} < 90 THEN PUBLISH TOPIC "alerts/quality/low_rate" WITH {station} + ": " + {rate} + "%" ``` Create structured event logs with context: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE MODEL EventLog COLLAPSED ADD STRING "event_id" ADD STRING "event_type" ADD STRING "source" ADD STRING "description" ADD STRING "severity" ADD STRING "timestamp" DEFINE ACTION LogEvent ON TOPIC "events/+/occurred" DO SET "event_type" WITH TOPIC POSITION 2 PUBLISH MODEL EventLog TO "logs/events/" + {event_type} WITH event_id = (RANDOM UUID) event_type = {event_type} source = (GET JSON "source" IN PAYLOAD AS STRING) description = (GET JSON "message" IN PAYLOAD AS STRING) severity = (GET JSON "severity" IN PAYLOAD AS STRING) timestamp = TIMESTAMP "UTC" ``` *** ## JSON vs protobuf on the destination topic `PUBLISH MODEL` writes whatever format the model declares: | Model format | Payload on **`TO "…"`** | | -------------------------------- | -------------------------------------------------------------- | | `WITH FORMAT JSON` (default) | JSON string | | `WITH FORMAT PROTOBUF` / `PROTO` | Raw protobuf **bytes** | | `WITH FORMAT BOTH` | JSON on the main topic + binary on a `/protobuf` sidecar topic | Trigger-based models (`WITH TOPIC` + `AS TRIGGER`) still auto-publish JSON. Use a `COLLAPSED` model and `PUBLISH MODEL` when a gateway must receive protobuf. Nested messages you fill on publish use `ADD MODEL Child "field"`, not indented `ADD OBJECT`. ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE MODEL TelemetryMessage WITH FORMAT PROTOBUF COLLAPSED ADD INT "message_type" PROTO_TAG 1 ADD DOUBLE "temperature" PROTO_TAG 2 ADD DOUBLE "pressure" PROTO_TAG 3 ``` The Action copies JSON tags into that envelope and publishes **bytes**: ```lot wrap focus={6-9} theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} DEFINE ACTION PublishTelemetry ON TOPIC "plant/+/tags" DO SET "temp" WITH GET JSON "Temperature" IN PAYLOAD AS DOUBLE SET "pressure" WITH GET JSON "Pressure" IN PAYLOAD AS DOUBLE PUBLISH MODEL TelemetryMessage TO "plant/gateway/telemetry" WITH message_type = 2 temperature = {temp} pressure = {pressure} ``` Full type mapping, `PROTO_TAG`, and `GET PROTO` are on [Protobuf Models](./protobuf). *** ## Best Practices Explicit type casting prevents runtime errors: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} // Good SET "temp" WITH (GET JSON "temperature" IN PAYLOAD AS DOUBLE) // Risky SET "temp" WITH (GET JSON "temperature" IN PAYLOAD) ``` Check data before publishing: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} SET "value" WITH (GET JSON "value" IN PAYLOAD AS DOUBLE) IF {value} >= 0 AND {value} <= 100 THEN PUBLISH MODEL ValidData TO "output" WITH value = {value} ELSE PUBLISH TOPIC "errors/validation" WITH "Invalid value: " + {value} ``` Include identifiers in output topics for easy filtering: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} // For topic "sensors/temp001/data" - wildcard is at position 2 SET "sensor_id" WITH TOPIC POSITION 2 PUBLISH MODEL SensorData TO "processed/" + {sensor_id} + "/data" WITH ... ``` Use `RANDOM UUID` for record identification: ```lot wrap theme={"theme":"css-variables","languages":{"custom":["/languages/lot.json"]}} PUBLISH MODEL Record TO "records/new" WITH record_id = (RANDOM UUID) ... ``` ## Next Steps See complete examples for common use cases. Review available operations for action logic.