The Mapping Details window displays both ends of the association and the key properties for the entity type at each End.įor each key property, click the Column field, and select the column to which the property will map. Select the table to which the association will map. This displays the association mapping in the Mapping Details window.Ī drop-down list appears that includes all the tables in the storage model. Right-click an association in the design surface and select Table Mapping. If a referential constraint is specified then a foreign key property is included in the entity and you can use the Mapping Details for the entity to control which column the foreign key maps to. You can only map details for the associations that do not have a referential constraint specified. You can specify how an association maps to the database in the Mapping Details window of the EF Designer. The entity's key properties are added to the Principal Key list in the dialog box.įrom the Dependent drop-down list, select the dependent entity in the referential constraint.įor each principal key that has a dependent key, select a corresponding dependent key from the drop-down lists in the Dependent Key column. The Referential Constraint dialog box appears.įrom the Principal drop-down list, select the principal entity in the referential constraint. edmx file.ĭouble-click the association that you want to edit. When you use the EF Designer to add or edit a referential constraint, the EF Designer adds or modifies a ReferentialConstraint element in the CSDL content of the. If you checked the Add foreign key properties to the Entity checkbox when creating a relationship, this referential constraint was added for you. Entity Framework uses a referential constraint to identify that a property acts as the foreign key for a relationship. It is recommended that you always expose foreign keys for relationships in your entities. Include Foreign Key Properties in Your Entities (Referential Constraints) Select one or more associations and press the DELETE key. Right-click the association on the EF Designer surface and select Delete. To delete an association do one of the following: If you add no navigation properties, you must choose to add foreign key properties in order to access entities at the ends of the association. If you add only one navigation property, the association will be traversable in only one direction. You can choose to not add navigation properties or foreign key properties to the entities at the ends of the association by clearing the **Navigation Property **and **Add foreign key properties to the Entity **checkboxes. With foreign keys exposed, the relationship between the entities is managed with a ReferentialConstraint element (a child element of the Association element). This information is specified in two child End elements.Īt run time, entity type instances at one end of an association can be accessed through navigation properties or foreign keys (if you choose to expose foreign keys in your entities). The multiplicity of an association end can have a value of one (1), zero or one (0.1), or many (*). An association must specify the entity types that are involved in the relationship and the possible number of entity types at each end of the relationship, which is known as the multiplicity. edmx file, an Association element defines a relationship between two entity types. When you design your model using the EF Designer, an. You can ignore these warnings because after you choose to generate the database from the model, the errors will go away. When you build the conceptual model, warnings about unmapped entities and associations may appear in the Error List.
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