14.16 DataView Object

Superclass	baseView
Description	The data view is a means of receiving and supplying data for client-facing components, such as web pages or web services. In other words, a data-view allows information to be moved intelligently between processing tiers, mapping between what the user wants to see and what the data store holds. A data-view can be inbound (for client input), outbound (present fields read from persistent storage) and combinations of in- and outbound. The data-view also has data aggregation and manipulation features: there can be an underlying entity (the 'initial entity') and attributes of entities related to that can be included in the data-view virtual (calculated) fields can be presented attributes in persistent storage can be calculated from input fields. Data-views can be updated. In the standard implementation, data-views are read by direct SQL calls (to optimise performance) with the SQL being build automatically, but updated via entity beans or their .NET equivalent (to reuse validation and entity processing logic). Validation can be specified on the data view or its fields, and this is additional to the validation from information tied to persistent storage. Data-views are typically processed by one or more session bean methods. Therefore, the data-view is a way of specifying the data required for a UML use case and how that is mapped onto the data tier. Data views can be related to a number of other data views. For example, an Order/OrderLine screen could require a set of information for the Order and a related set of information for the OrderLine. This is represented as a relationship between data-views, in just the same way that entities or data-base tables are related. The data-view pattern is a superset of the 'transfer object assembler' Core J2EE pattern. A value object (also known as the transfer object) is automatically generated for the data-view.
Contained Lists	1 Name   typeParameter Type   java:typeParameter Inherited from   java:referenceType   2 Name   import Type   String Inherited from   java:referenceType   3 Name   field Type   java:field Inherited from   internalClass   4 Name   method Type   java:method Inherited from   internalClass   5 Name   implements Type   String Inherited from   java:jwclass   6 Name   constraint Type   constraint Inherited from   internalClass   7 Name   style Type   String Inherited from   internalClass   8 Name   dataViewToAttributeMapper Type   dataViewToAttributeMapper Indexed property   name   9 Name   rolesReadonly Type   String Inherited from   entity   10 Name   rolesAllowed Type   String Inherited from   entity   11 Name   rolesBlocked Type   String Inherited from   entity
Validation	The 'generateMaintenancePages' flag must not be set if there is no initial entity
Inherited properties	name from baseView.name description from java:interfaceMethod.description template from java:interfaceMethod.template text from java:method.text jwpattern (base property) typeDeclaration from java:referenceType.typeDeclaration extends from java:referenceType.extends headerComment from java:referenceType.headerComment customerHeaderComment from java:referenceType.customerHeaderComment package from baseViewRelation.package generateLogLevel from constraint.generateLogLevel access from baseView.access annotation from java:interfaceMethod.annotation abstract from java:method.abstract static from java:method.static serializable from java:jwclass.serializable final from java:method.final alwaysGenerateTriggers from internalClass.alwaysGenerateTriggers constraintExceptionType from constraint.constraintExceptionType uid from constraint.uid group from businessMethod.group userNameBase from businessMethod.userNameBase supportsUpload from baseView.supportsUpload generateMaintenancePages from baseView.generateMaintenancePages lookupPageCreated from baseView.lookupPageCreated generateMaintenanceSession from baseView.generateMaintenanceSession convertEmptyStringsToNull from baseView.convertEmptyStringsToNull generateDataviewImplClass from baseView.generateDataviewImplClass screenPosition from baseView.screenPosition initialEntity from baseView.initialEntity sqlStatement from baseView.sqlStatement additionalWhereClause from baseView.additionalWhereClause sqlOrder from baseView.sqlOrder container from baseView.container dataviewTriggers from baseView.dataviewTriggers

14.16.1  Property 'lockOnRead'

14.16.2  Property 'viewIsReferencedByPage'

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