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Limitations of the Automated Entity Framework Tools

Advantage .NET Data Provider

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The Entity Data Model is made of three parts.  The first part is a storage metadata schema, which defines the layout of the data.  The second part is a conceptual schema, which defines the object model used by the application.  Finally, the mapping specification connects the conceptual schema with the storage metadata schema.

 

The Entity Framework provides a number of automated tools to generate an Entity Data Model from an existing database.  These automated tools read the available schema information from a database and then build a conceptual schema, a storage metadata schema and a mapping specification.  To function properly these automated tools require primary keys to be defined on all tables in the database with a constraint preventing NULL values on primary key fields.  Currently only the Advantage Proprietary (ADS_ADT) format and the Visual FoxPro (ADS_VFP) support both primary keys and NULL field constraints when bound to a data dictionary.

 

For databases that do not meet these requirements, the storage metadata schema can be implemented manually.  Once a storage metadata schema has been defined, edgmen2.exe from Microsoft can be used to generate the conceptual schema and mapping specification.  For information on writing a storage metadata schema see the MSDN.

 

See Also

Entity Framework Support

Unsupported Entity Framework Functionality