This example implements connection filtering for reporting applications in multi-user environments. The application sets the current user ID in SESSION_CONTEXT. Once the database connection opens, security policies filter visible rows for the current user.

1. This example uses a SQL file (instnwnd.sql). Execute it to recreate the database locally. Do not forget to update appsettings.json so that the connection string works in your environment.

2. Execute the script below. This script extends the database as follows:

• Creates a new schema and predicate function that uses the user ID stored in SESSION_CONTEXT to filter rows.
• Creates a security policy that adds this function as a filter predicate and a block predicate on Orders.

CREATE SCHEMA Security;
GO

CREATE FUNCTION Security.fn_securitypredicate(@EmployeeId int)
    RETURNS TABLE
    WITH SCHEMABINDING
AS
    RETURN SELECT 1 AS fn_securitypredicate_result
    WHERE CAST(SESSION_CONTEXT(N'EmployeeId') AS int) = @EmployeeId;
GO

CREATE SECURITY POLICY Security.OrdersFilter
    ADD FILTER PREDICATE Security.fn_securitypredicate(EmployeeId)
        ON dbo.Orders,
    ADD BLOCK PREDICATE Security.fn_securitypredicate(EmployeeId)
        ON dbo.Orders AFTER INSERT
    WITH (STATE = ON);
GO

Use the following script to clean up database resources:

DROP SECURITY POLICY Security.OrdersFilter;

--DROP TABLE Orders;

DROP FUNCTION Security.fn_securitypredicate;

DROP SCHEMA Security;

Create an IDBConnectionInterceptor object (RLSConnectionInterceptor.cs in this example). When the database connection opens, store the current user ID in SESSION_CONTEXT. Modify queries to the Orders table - filter data by user ID (so as to implement database behavior equivalent to connection filtering). Register RLSConnectionInterceptor as an extension in IServiceCollection.

When you run the application, a registration form (Login.cshtml) will appear on-screen. Select a user to generate a report with filtered data.

• RLSConnectionInterceptor.cs
• Program.cs
• AccountController.cs
• Login.cshtml

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