Source
factory ManagedDataModelException.noPrimaryKey(ManagedEntity entity) {
return new ManagedDataModelException(
"Class '${_getPersistentClassName(entity)}'"
" doesn't declare a primary key property. All 'ManagedObject' subclasses "
"must have a primary key. Usually, this means you want to add '@managedPrimaryKey int id;' "
"to ${_getPersistentClassName(entity)}, but if you want more control over "
"the type of primary key, declare the property as one of "
"${ManagedPropertyDescription.supportedDartTypes.join(", ")} and "
"add '@ManagedColumnAttribute(primaryKey: true)' above it.");
}