Reverse Engineering (Scaffolding)
Reverse engineering (via scaffolding) is a process which streamlines OR/M by automatically constructing classes for all of the tables and views available via the HDFS schema. This process also creates a CDataContext class, which extends DbContext and exposes the DbSet properties that represent the tables in the data source.
Install Entity Framework Core Tools
If you're making use of scaffolding in a console app, you'll first need to install the EF Tools via the Package Manager Console (PMC). Use one of the following:
Install-Package Microsoft.EntityFrameworkCore.Tools -Version 3.0 //Run this command if using EF Core 3.0 Install-Package Microsoft.EntityFrameworkCore.Tools -Version 3.1 //Run this command if using EF Core 3.1 Install-Package Microsoft.EntityFrameworkCore.Tools -Version 5.0 //Run this command if using EF Core 5.0
Scaffolding is performed using the PMC in Visual Studio. You can use following commands to scaffold.
Scaffold All Tables
Use the following command to scaffold all tables and views from the schema into your Models folder:
Scaffold-DbContext "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;" CData.EntityFrameworkCore.HDFS -OutputDir Models -Context HDFSContext
Scaffold A Subset of Tables
You can also refine the scaffolding process to only create classes for a limited selection of tables. This is especially useful when a large schema is taking a long time to scaffold due to the large number of classes it has to generate. This is accomplished by specifying the tables/views that you want to scaffold at the end of your Scaffold-DbContext command in the PMC.
Scaffold-DbContext "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;" CData.EntityFrameworkCore.HDFS -OutputDir Models -Context HDFSContext -Tables Files
Updating your Data Model
If you would like to add re-scaffold to update the model additional table classes after the initial generation, simply add a '-Force' argument to any Scaffold-DbContext command. The existing model will then be overwritten with your changes.