Generated code - Using the TypedList classes, SelfServicing
Preface
LLLBLGen Pro supports read-only lists based on a selection of entity fields
from one or more entities with a relationship, called a
TypedList. A
TypedList is generated as a typed
DataTable, which is a
variant of the typed DataSet concept included in Visual Studio.NET. A typed
DataTable is a class which derives from the .NET DataTable and defines
properties and a row class to access the individual fields in a typed
fashion.
In this section the
TypedList classes are briefly
discussed and their usage is illustrated using examples.
Instantiating and using a TypedList
Using a
TypedList is similar to using a
TypedView, both will be generated as typed DataTables. There is a difference however
in how you formulate filters and sortclauses for a
TypedList. The reason for this is that a
TypedList is constructed using existing entity fields, while a
TypedView
uses its own field definitions. When you want
to construct a filter for a
TypedList, you have to specify
field indexes of fields in the entities which are the base of
the typed list; you can filter on fields which are not included in the typed list itself as in the column set of the typed list.
In the example below, we'll use a
TypedList created from the
entities
Customer and
Order and include the following fields
in the resultset: Order.OrderID, Order.OrderDate, Order.ShippedDate,
Customer.CustomerID, Customer.CompanyName. You can filter on any field in
Order or
Customer or both. Also, you can sort on any field in
Order or Customer or both. Let's filter this
TypedList on all orders
from customers from 'Brazil', and sort the list on the field Order.Freight,
ascending. The
TypedList is called OrderCustomer.
// [C#]
OrderCustomerTypedList orderCustomer = new OrderCustomerTypedList();
IPredicateExpression filter = new PredicateExpression(CustomerFields.Country == "Brazil");
ISortExpression sorter = new SortExpression(OrderFields.Freight | SortOperator.Ascending);
// Set allowDuplicates to true, because we sort on a field that is not in our resultset and we use SqlServer.
orderCustomer.Fill(0, sorter, true, filter);
' [VB.NET]
Dim orderCustomer As New OrderCustomerTypedList()
Dim filter As New PredicateExpression(CustomerFields.Country="Brazil")
Dim sorter As New SortExpression(OrderFields.Freight Or SortOperator.Ascending)
' Set allowDuplicates to true, because we sort on a field that is not in our resultset and we use SqlServer.
orderCustomer.Fill(0, sorter, True, filter)
The
TypedList object is now filled with the rows for the 5 columns
we've specified in the
TypedList editor, sorted on Order.Freight
ascending and filtered on Customer.Country equals "Brazil".
