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CARP Documentation

1. Define the data

Start with the answer, not the Bluetooth. One sip is: how hot, how much.

/// One sip from the smart mug.
@JsonSerializable(includeIfNull: false)
class MugSip extends Data {
  /// How hot the coffee was, in degrees Celsius.
  double temperature;


  /// How much was drunk, in milliliters.
  int volume;


  MugSip({required this.temperature, required this.volume});


  @override
  String get jsonType => MugSamplingPackage.SIP;


  @override
  Function get fromJsonFunction => _$MugSipFromJson;
  factory MugSip.fromJson(Map<String, dynamic> json) =>
      FromJsonFactory().fromJson(json) as MugSip;
  @override
  Map<String, dynamic> toJson() => _$MugSipToJson(this);
}

What each line is for:

  • extends Data: everything a probe measures is a Data object. It ends up inside a Measurement.
  • @JsonSerializable: the data is written to JSON (JSON serialization). build_runner generates _$MugSipFromJson and _$MugSipToJson.
  • jsonType: the name of the measure type, dk.cachet.carp.mug.sip. It becomes __type in the JSON and is the same string a protocol uses in Measure(type: ...).
  • fromJsonFunction and fromJson: how CAMS creates a MugSip from JSON. It finds it through FromJsonFactory, where you register it in step 4.

What a stored sip looks like

Section titled “What a stored sip looks like”
{
  "sensorStartTime": 1790788396315955,
  "data": {
    "__type": "dk.cachet.carp.mug.sip",
    "temperature": 61.0,
    "volume": 25
  }
}

sensorStartTime is microseconds since epoch (UTC). The data part is your class.

Generate the JSON code

Section titled “Generate the JSON code”
Terminal window
dart run build_runner build