Scaffolding Or Reverse Engineering
ODP.NET EF Core supports scaffolding the following tables and views:
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Relational tables and views
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Materialized views
By convention, ODP.NET EF Core maps an appropriate .NET data type based on the Oracle Database data type and its characteristics.
When scaffolding, developers may wish to change the default data type mappings between Oracle Database and .NET. When modifying .NET CLR types of the generated entity's property, remove the auto-generated HasColumnType() Fluent API in the model. For example, an Oracle NUMBER(4) is scaffolded to a .NET Byte data type by default. If the .NET CLR data type is changed to .NET Short or Int16 data type, then an invalid cast exception at runtime may occur until the HasColumnType("NUMBER(4)") has been removed.
Data Type Mapping
This table shows the default mappings.
Table 5-2 ODP.NET Entity Framework Core Reverse Engineering Data Type Default Mappings
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Scaffolding Tables from Another Schema
Developers can scaffold tables from other schemas other than the user/schema they are connected with. The connected user requires privileges to access the other schema's objects. Once these privileges are granted, developers can use the Package Manager Console (PMC) tools for Entity Framework Core to perform the scaffolding operation. For example:
Scaffold-DbContext "User Id=scott;Password=<password>;Data Source=myhost:1521/mydb;"
Oracle.EntityFrameworkCore -Schemas HR -Tables EMPLOYEES Developers can use the –Schemas and –Tables parameters to specify which schemas and tables/views to scaffold for an Entity Framework Core model. If connecting with one user/schema to create tables from a second schema, the user must have at least SELECT privileges for that second schema.
The following table displays the ODP.NET Entity Framework Core behavior when the –Schemas and/or –Tables parameter is specified or left as default while scaffolding a pre-existing model using the Package Manager Console command, Scaffold-DbContext. All sample command excerpts below use Scaffold-DbContext syntax. Similar functionality is available using the EF Core tools command, dotnet ef dbcontext scaffold.
Table 5-3 Schema and Table Filter Mapping
| Mapping of Schema and Table Filters | No Schema Filter | Schema Filter |
|---|---|---|
|
No Table Filter |
Generates all tables/views within current user/schema Box 1 |
Generates all tables/views in specified user(s)/schema(s) Box 2 |
|
Table Filter |
Generates specified tables/views within current user/schema Box 3 |
Generates specified tables/views within current schema and all tables/views in specified user(s)/schema(s) Filtered results include combined Box 2 and Box 3 results. |
It is possible to scaffold tables/views in other schemas by appending the schema name in front: -Tables <schema>.<table/view>
For example, the following snippet would scaffold three tables in three different schemas:
-Tables SCHEMA1.TABLEA, SCHEMA2.TABLEB, SCHEMA3.TABLEC
If the schema or table name contains any special characters, such as a period, then use brackets to delimit the schema and table names when using the –Tables option.
-Tables [SCHEMA1].[TABLEA]
Scaffolding Views
Oracle supports scaffolding database relational and materialized views only. These views can be either read-only or updatable. Use the -Tables parameter to specify the views to scaffold. If the parameter is left blank (default), all the user tables, relational views, and materialized views will be scaffolded.