DbExpressionBuilder.RefFromKey Method
Creates a new DbRefExpression that encodes a reference to a specific Entity based on key values.
Assembly: EntityFramework (in EntityFramework.dll)
Name | Description | |
---|---|---|
![]() ![]() | RefFromKey(EntitySet, DbExpression) | Creates a new DbRefExpression that encodes a reference to a specific Entity based on key values. |
![]() ![]() | RefFromKey(EntitySet, DbExpression, EntityType) | Creates a new DbRefExpression that encodes a reference to a specific Entity based on key values. |
DbExpressionBuilder.RefFromKey Method (EntitySet, DbExpression)
Creates a new DbRefExpression that encodes a reference to a specific Entity based on key values.
Parameters
- entitySet
-
Type:
System.Data.Entity.Core.Metadata.Edm.EntitySet
The Entity set in which the referenced element resides.
- keyRow
-
Type:
System.Data.Entity.Core.Common.CommandTrees.DbExpression
A DbExpression that constructs a record with columns that match (in number, type, and order) the Key properties of the referenced Entity type.
Return Value
Type: System.Data.Entity.Core.Common.CommandTrees.DbRefExpressionA new DbRefExpression that references the element with the specified key values in the given Entity set.
Exception | Condition |
---|---|
ArgumentNullException | entitySet or keyRow is null. |
ArgumentException | keyRow |
keyRow should be an expression that specifies the key values that identify the referenced entity within the given entity set.The result type of keyRow should contain a corresponding column for each key property defined byentitySet's entity type.
DbExpressionBuilder.RefFromKey Method (EntitySet, DbExpression, EntityType)
Creates a new DbRefExpression that encodes a reference to a specific Entity based on key values.
public static DbRefExpression RefFromKey( this EntitySet entitySet, DbExpression keyRow, EntityType entityType )
Parameters
- entitySet
-
Type:
System.Data.Entity.Core.Metadata.Edm.EntitySet
The Entity set in which the referenced element resides.
- keyRow
-
Type:
System.Data.Entity.Core.Common.CommandTrees.DbExpression
A DbExpression that constructs a record with columns that match (in number, type, and order) the Key properties of the referenced Entity type.
- entityType
-
Type:
System.Data.Entity.Core.Metadata.Edm.EntityType
The type of the Entity that the reference should refer to.
Return Value
Type: System.Data.Entity.Core.Common.CommandTrees.DbRefExpressionA new DbRefExpression that references the element with the specified key values in the given Entity set.
Exception | Condition |
---|---|
ArgumentNullException | entitySet, keyRow or entityType is null. |
ArgumentException | entityType is not in the same type hierarchy as the entity set's entity type, or keyRow does not have a record result type that matches the key properties of the referenced entity set's entity type. |
keyRow should be an expression that specifies the key values that identify the referenced entity within the given entity set. The result type of keyRow should contain a corresponding column for each key property defined by entitySet's entity type.