General Actions:
Last modified on August 15, 2012 17:22
Examine entity model metadata programmatically by interrogating the EntityMetadata object held in the EntityMetadataStore singleton.
The EntityMetadataStore
DevForce maintains a thread-safe repository of metadata for all types in a domain model. Applications can query the store using the GetEntityMetadata() method for a type:
| C# | EntityMetadata employeeEntityMetaData = EntityMetadataStore.Instance.GetEntityMetadata( typeof(DomainModel.Employee)); |
| VB | Dim employeeEntityMetaData As EntityMetadata = _ EntityMetadataStore.Instance.GetEntityMetadata( _ GetType(DomainModel.Employee)) |
You can also access the EntityMetadata for any entity instance using its EntityAspect:
| C# | var cust = _em1.Customers.First(); var metadata = cust.EntityAspect.EntityMetadata; |
| VB | Dim cust = _em1.Customers.First() Dim metadata = cust.EntityAspect.EntityMetadata |
The EntityMetadata provides the following members:
The table below provides an explanation for a few key members:
| Property | CanQueryByEntityKey | Gets whether primary key queries are allowed. |
| Property | ComplexTypeProperties | Returns a collection of DataEntityProperties that describe complex object properties for entities of this type. |
| Property | ConcurrencyProperties | Returns a collection of DataEntityProperties that are concurrency properties for entities of this type. |
| Method | CreateEntity() | Creates a new entity of the type described by this metadata item. |
| Property | DataProperties | Returns a collection of DataEntityProperties for entities of this type. |
| Property | DataSourceKeyName | Gets the name of the Data Source Key associated with this type. |
| Property | DefaultValueFunction | Static - Use to override how DevForce sets the default value for a data entity property. |
| Property | EntityProperties | Returns a collection of EntityProperties that belong to entities of this type. |
| Property | EntityType | Gets the type of the entity. |
| Property | ForeignKeyProperties | Returns a collection of ForegnKey DataEntityProperties |
| Property | HasStoreGeneratedId | Returns whether this entity type has a store generated id. |
| Property | IsComplexObjectType | Returns whether this metadata describes a ComplexObject. |
| Property | KeyProperties | Returns a collection of DataEntityProperties that are keys for entities of this type. |
| Property | NavigationProperties | Returns a collection of NavigationEntityProperties for entities of this type. |
Property Metadata
When DevForce generates the code for your domain model it includes a nested class called PropertyMetadata within each generated Entity. Within PropertyMetadata are static fields for all the EntityProperty definitions within the entity. You’ll see a DataEntityProperty for every non-navigation property, and either a NavigationScalarEntityProperty or NavigationListEntityProperty for all navigation properties.
You can easily access these properties at any time via the static field definitions:
| C# | var dataProp = Customer.PropertyMetadata.Id; var navListProp = Customer.PropertyMetadata.OrderSummaries; var navScalarProp = OrderSummary.PropertyMetadata.Customer; |
| VB | Dim dataProp = Customer.PropertyMetadata.Id Dim navListProp = Customer.PropertyMetadata.OrderSummaries Dim navScalarProp = OrderSummary.PropertyMetadata.Customer |
Also generated into each Entity class is a nested class called EntityPropertyNames. This class contains string constants for all the property names within the entity.
| C# | public partial class Employee : IbEm.Entity { public new partial class EntityPropertyNames : IbEm.Entity.EntityPropertyNames { public const String Id = "Id"; public const String LastName = "LastName"; public const String FirstName = "FirstName"; } } |
| VB | Partial Public Class Employee Inherits IbEm.Entity Partial Public Shadows Class EntityPropertyNames Inherits IbEm.Entity.EntityPropertyNames Public Const Id As String = "Id" Public Const LastName As String = "LastName" Public Const FirstName As String = "FirstName" End Class End Class |