Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
Facets in conceptual schema definition language (CSDL) represent constraints on properties of entity types and complex types. Facets appear as XML attributes on the following CSDL elements:
The following table describes the facets that are supported in CSDL. All facets are optional. Some facets listed below are used by the Entity Framework when generating a database from a conceptual model. For more information, see Generate Database Wizard.
Note
For information about data types in a conceptual model, see Conceptual Model Types (CSDL).
| Facet | Description | Applies to | Used for the database generation | Used by the runtime |
|---|---|---|---|---|
Collation |
Specifies the collating sequence (or sorting sequence) to be used when performing comparison and ordering operations on values of the property. |
Edm.String |
Yes |
No |
ConcurrencyMode |
Indicates that the value of the property should be used for optimistic concurrency checks. |
All EDMSimpleType properties |
No |
Yes |
Default |
Specifies the default value of the property if no value is supplied upon instantiation. |
All EDMSimpleType properties |
Yes |
Yes |
FixedLength |
Specifies whether the length of the property value can vary. |
Edm.Binary, Edm.String |
Yes |
No |
MaxLength |
Specifies the maximum length of the property value. |
Edm.Binary, Edm.String |
Yes |
No |
Nullable |
Specifies whether the property can have a null value. |
All EDMSimpleType properties |
Yes |
Yes |
Precision |
For properties of type Decimal, specifies the number of digits a property value can have. For properties of type Time, DateTime, and DateTimeOffset, specifies the number of digits for the fractional part of seconds of the property value. |
Edm.DateTime, Edm.DateTimeOffset, Edm.Decimal, and Edm.Time. |
Yes |
No |
Scale |
Specifies the number of digits to the right of the decimal point for the property value. |
Edm.Decimal |
Yes |
No |
Unicode |
Indicates whether the property value is stored as Unicode. |
Edm.String |
Yes |
Yes |
Note When generating a database from a conceptual model, the Generate Database Wizard will recognize the value of the StoreGeneratedPattern attribute on a Property element if it is in the following namespace: https://schemas.microsoft.com/ado/2009/02/edm/annotation. The supported values for the attribute are Identity and Computed. A value of Identity will produce a database column with an identity value that is generated in the database. A value of Computed will produce a column with a value that is computed in the database.
Example
The following example shows facets applied to the properties of an entity type:
<EntityType Name="Product">
<Key>
<PropertyRef Name="ProductId" />
</Key>
<Property Type="Int32"
Name="ProductId" Nullable="false"
a:StoreGeneratedPattern="Identity"
xmlns:a="https://schemas.microsoft.com/ado/2009/02/edm/annotation" />
<Property Type="String"
Name="ProductName"
Nullable="false"
MaxLength="50" />
<Property Type="String"
Name="Location"
Nullable="true"
MaxLength="25" />
</EntityType>
For more information, see Property Element (CSDL).
See Also
Reference
System.Data.Metadata.Edm.Facet
Concepts
Other Resources
facet (Entity Data Model)
CSDL, SSDL, and MSL Specifications