Selects a property from the object being queried to add a filtering expression.
You use this property to add filtering expression to a query. The expressions are added to the SQL WHERE clause of the generated query.
You provide a closure for
propertyIdentifier that returns a property of its argument. Its argument is always
an empty instance of the object being queried. You invoke methods like QueryExpression.lessThan on the
object returned from this method to add an expression to this query.
final query = Query<Employee>() ..where((e) => e.name).equalTo("Bob");
You may select properties of relationships using this method.
final query = Query<Employee>() ..where((e) => e.manager.name).equalTo("Sally");
QueryExpression<T, InstanceType> where<T>( T propertyIdentifier(InstanceType x));