I almost have it working now, but it's unfortunate how many places I had to change :(

I had to change:

1. OperatorRepository and IOperatorRepository

2. OperatorAdapter and IOperatorAdapter

3. SeachModel

4. OperatorApiController (but this is what was the goal)

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I also noticed this

SELECT TOP (15) 
    [Project1].[C1] AS [C1], 
    [Project1].[op_code] AS [op_code], 
    [Project1].[first_name] AS [first_name], 
    [Project1].[last_name] AS [last_name], 
    [Project1].[hidden] AS [hidden], 
    [Project1].[C2] AS [C2]
    FROM ( SELECT [Project1].[op_code] AS [op_code], [Project1].[first_name] AS [first_name], [Project1].[last_name] AS [last_name], [Project1].[hidden] AS [hidden], [Project1].[C1] AS [C1], [Project1].[C2] AS [C2], row_number() OVER (ORDER BY [Project1].[op_code] ASC) AS [row_number]
        FROM ( SELECT 
            [Extent1].[op_code] AS [op_code], 
            [Extent1].[first_name] AS [first_name], 
            [Extent1].[last_name] AS [last_name], 
            [Extent1].[hidden] AS [hidden], 
            1 AS [C1], 
            N'' AS [C2]
            FROM [dbo].[operator] AS [Extent1]
            WHERE 0 = [Extent1].[hidden]
        )  AS [Project1]
    )  AS [Project1]
    WHERE [Project1].[row_number] > 0
    ORDER BY [Project1].[op_code] ASC

I had to use OpHashCode = '' instead of using op.OpHashCode as this is calculated property.

I also forgot to use RoleNo, so I'll add this to the code. But the basic list now works and uses much simpler query.