lookupValue<T extends Model> method

Future<T> lookupValue<T extends Model>(
  1. Key key, {
  2. T orElse()?,
})

Looks up a single key within this transaction, and returns the associated Model object.

If orElse is specified, then it will be consulted to provide a default value for the model object in the event that key was not found within the transaction.

If the key is not found within the transaction and orElse was not specified, then a KeyNotFoundException will be thrown.

Implementation

Future<T> lookupValue<T extends Model>(Key key,
    {T Function()? orElse}) async {
  final values = await lookup<T>(<Key>[key]);
  assert(values.length == 1);
  var value = values.single;
  if (value == null) {
    if (orElse != null) {
      value = orElse();
    } else {
      throw KeyNotFoundException(key);
    }
  }
  return value;
}