Microsoft Dynamics AX 2009 : Application Model Elements (part 2) - Value Type, Database, and Data Association Model Elements

Value Type, Database, and Data Association Model Elements

Figure 2 illustrates the value type, database, and data association element categories that are located in the Data Dictionary node in the AOT. Configuration key elements can be associated with base enumeration and extended data type elements as well as with table, view, and map elements. Table, view, and map application elements can also be associated with security key elements.

Figure 2. Value type, database, and data association model elements

Value Type Model Elements

A base enumeration element (sometimes shortened to enum) defines a name for a group of symbolic constants that are used in X++ code statements. For example, an enumeration with the name WeekDay can be defined to name the group of symbolic constants that includes Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday.

An extended data type element can extend a base enumeration by providing a new name for a group of symbolic constants that includes the base enumeration elements. An extended data type element can also extend the string, boolean, int, real, date, time, UtcDateTime, int64, guid, and container types. An extended data type definition can also comprise a set of application parameters that define how the Dynamics AX runtime renders user interface controls. For example, an extended data type representing an account number extends a string value type, restricts its length to 10 characters, and sets its user interface label to “Account number.”

Extended data types also support inheritance. For example, an extended data type that defines an account number can be specialized by other extended data types defining customer and vendor account numbers. The specialized extended data type inherits properties, such as string length, label, and help text. You can override some of the properties on the specialized extended data type. You constrain the possible values of an extended data type and define a database table association by adding a relationship from the extended data type to a table field element. The Dynamics AX runtime automatically ensures that the values of the extended data type are consistent with this relationship. The runtime also uses the defined relationship to navigate between rich client and Web client main table forms when a user selects the Go To The Main Table Form menu item. This menu item appears when a user right-clicks a form data grid column that is mapped to a table element field whose type is an extended data type with a defined relationship.

Database Model Elements

Database model elements are database table and view definitions that correspond to database server entities and relationships as well as query elements that define database query statements. The MorphX IDE synchronizes table and view element definitions with database schema definitions. This feature allows Dynamics AX to use either Microsoft SQL Server or Oracle database server as an application database. MorphX synchronizes only those database elements that have configuration keys enabled and corresponding valid license keys.

Database element keys and indexes are used to create database entity keys and indexes, but data element interrelationships are not used to create integrity relationships in a database. Instead, they validate data entries to automatically join and select database data as a user navigates between forms, and they join data sources associated with a form. For example, a user sees confirmations only for the selected sales orders when navigating from a sales order form to a sales order confirmation form. Moreover, MorphX automatically converts between X++ programming value types such as string, enum, and boolean and their corresponding database data types, such as nvarchar and int. For example, an X++ string defined to have a maximum length of 10 characters is stored as a database nvarchar data type defined to have a maximum length of 10 characters.

A table element can also define table field groups, menu item references, table relationships, delete actions, and methods that are used by the Dynamics AX runtime when it renders data entry presentation controls and ensures the referential integrity of the database. The X++ editor also uses these elements to support developers with IntelliSense when they write X++ statements that create, read, update, and delete data in the database. You can also use the AOT to associate table elements with data source elements on forms, reports, queries, and views.

View elements define database table view entities and are synchronized with the application database. View elements can include a query that filters data in a table or data joined from multiple tables. View element definitions also include table field mappings and methods. Views are read-only and primarily provide an efficient method for reading data. View elements can be associated with form and report data sources and are instantiated in X++ variable declarations.

Query elements define a database query structure that can be executed from X++ statements, particularly X++ statements used in classes that derive from the RunBase class. You add tables to query element data sources and specify how they should be joined. You also specify how data is returned from the query, such as by using sort order and range specifications.

Data Association Model Elements

Map elements don’t define database entities, so they’re not synchronized with the database. They actually define X++ programming elements that wrap table objects at run time. Map elements associate common fields and methods for tables that are not in third-normal form. For example, the CustTable and VendTable table elements in the Dynamics AX application model are mapped to the AddressMap map element so that developers can use one AddressMap object to access common address fields and methods. The MorphX compiler validates that table variables assigned to map variables are defined as valid element mappings.

Table collection elements define groups of tables that can be shared by two or more Dynamics AX companies that share virtual company accounts. The application administrator creates a virtual company and then adds table collections to it. The administrator also adds the virtual company accounts to an actual Dynamics AX company’s accounts. The Dynamics AX runtime uses the virtual company data area identifier instead of the actual company data area identifier when it inserts or reads data in the tables in the table collection.

Perspective elements define views on the Dynamics AX database model by grouping related tables. Perspectives are used to design and generate ad hoc reports in Microsoft SQL Server Reporting Services.

Class Model Elements

Class elements define the structure and behavior of business logic types that work on ERP reference data and business transaction data. These elements comprise object-oriented type definitions that instantiate business objects at run time. You define type declaration headers and methods by using the X++ programming language. You associate rich client and Web client menu item elements in the AOT with class element methods by using the property sheet in MorphX. This allows the Dynamics AX runtime to instantiate corresponding business logic objects when users select action, display, or output menu item controls on a user interface.

The Dynamics AX runtime also invokes business object methods when they overload event handlers on tables, forms, and reports. Class elements are also defined for application integration scenarios that aren’t driven by a user interface.