setOnce method Null safety

void setOnce(
  1. String prop,
  2. dynamic to

Works just like set(), except it will not overwrite existing property values. This is useful for properties like "First login date".

  • prop The name of the Mixpanel property. This must be a String, for example "Zip Code"
  • to The value of the Mixpanel property. For "Zip Code", this value might be the String "90210"


void setOnce(String prop, dynamic to) {
  if (_MixpanelHelper.isValidString(prop)) {
    Map<String, dynamic> properties = {prop: to};
        <String, dynamic>{'token': this._token, 'properties': properties});
  } else {
    developer.log('`people setOnce` failed: prop cannot be blank',
        name: 'Mixpanel');