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Xour

•Created by Xour on 8/4/2024 in #help

Issues with LINQ query to left join three tables

Hi everyone, I’m running into some issues with a LINQ query. I need to join three tables, but I’m having trouble getting the query to work as expected. The constraints are: - No navigation properties between the tables - Two tables (RobotNetworkStatus and RobotSystemStatus) contains either zero or one row for a given RobotSerialNumber - RobotNetworkInterfaces contains zero or more rows for any given RobotSerialNumber After poking at the docs (here and here), this is what I come up with, which is of course not working (cannot be evaluated property, and an exception is thrown):

var robotNetworkData = await (
        from ni in _dbContext.RobotNetworkInterfaces
        join ns in _dbContext.RobotNetworkStatus
            on ni.RobotSerialNumber equals ns.RobotSerialNumber into nsGroup
        from ns in nsGroup.DefaultIfEmpty()
        join ss in _dbContext.RobotSystemStatus
            on ni.RobotSerialNumber equals ss.RobotSerialNumber into ssGroup
        from ss in ssGroup.DefaultIfEmpty()
        where ni.RobotSerialNumber == request.SerialNumber
        group new { ni, nsGroup, ssGroup } by new { ni, ns, ss } into g
        select new
        {
            RobotNetworkStatus = g.Key.ns,
            RobotSystemStatus = g.Key.ss,
            RobotNetworkInterfaces = g.Select(nd => nd.ni).ToList()
        }
    )
    .AsNoTracking()
    .ToListAsync();

var robotNetworkData = await (
        from ni in _dbContext.RobotNetworkInterfaces
        join ns in _dbContext.RobotNetworkStatus
            on ni.RobotSerialNumber equals ns.RobotSerialNumber into nsGroup
        from ns in nsGroup.DefaultIfEmpty()
        join ss in _dbContext.RobotSystemStatus
            on ni.RobotSerialNumber equals ss.RobotSerialNumber into ssGroup
        from ss in ssGroup.DefaultIfEmpty()
        where ni.RobotSerialNumber == request.SerialNumber
        group new { ni, nsGroup, ssGroup } by new { ni, ns, ss } into g
        select new
        {
            RobotNetworkStatus = g.Key.ns,
            RobotSystemStatus = g.Key.ss,
            RobotNetworkInterfaces = g.Select(nd => nd.ni).ToList()
        }
    )
    .AsNoTracking()
    .ToListAsync();

I suspect the issue relies in the grouping. NGL, I was more or less guessing what to do here. Ideally I would like to get this fixed, but more importantly, I would love to understand how to fix it and how does it work. Any hit/help/advise/suggestions are most welcomed! Thanks! EDIT: If I remove the grouping it works, but for each row of RobotNetworkInterfaces I get all other rows as well.

8 replies

CC#

•Created by Xour on 5/6/2024 in #help

Options pattern in a shared class library

Hello all, I am looking to use options pattern in a shared class library, but I am not sure how should I go about it. The project structure is something like this:

- Api_1
    - Layer_1
    - Layer_2
    ..
- Api_2
    - Layer_1
    - Layer_2
    ..
- Shared class libraries
    - Class_library_1
    - Class_library_2
    ..

- Api_1
    - Layer_1
    - Layer_2
    ..
- Api_2
    - Layer_1
    - Layer_2
    ..
- Shared class libraries
    - Class_library_1
    - Class_library_2
    ..

What I need is to somewhat use options pattern in, say, Class_library_2 (or at least have access to the configuration provider in any way), but I am unsure what would be the proper way to do this. If I register the config in the Startup.cs of the Api_1 web project, those won't be available from Api_2. Should I create the option classes and register the config in both projects? Any hints or advice? Thanks a lot!

29 replies

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