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Sernik

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•Created by Sernik on 10/26/2022 in #help

Keyset pagination with filters

Hello everyone! I use this piece of code (probably very inefficient piece of code) to get employees from database using keyset pagination.

    public IEnumerable<EmployeeView> GetEmployees()
    {
        var amount = _appState.ItemsPerPage;

        var lastId = _appState.LastEmployeeId ?? 0;
        
        var employees = _context.Employees
            .AsNoTracking()
            .OrderBy(e => e.EmpNo)
            .Where(e => e.EmpNo > lastId);

        #region filters
        if (_appState.GenderFilter.GetAllowedValue(out var allowedGender))
            employees = employees.Where(e =>
                e.Gender[0] == allowedGender);

        if (_appState.DepartmentFilter.GetAllowedValue(out var allowedDepartment))
            employees = employees.Where(e =>
                _departmentService.GetDepartmentName(e.EmpNo) == allowedDepartment);

        if (_appState.SalaryFilter.GetAllowedValue(out var allowedSalary))
            employees = employees.Where(e =>
                _salaryService.GetSalaryValue(e.EmpNo) >= allowedSalary.From &&
                _salaryService.GetSalaryValue(e.EmpNo) <= allowedSalary.To);
        #endregion filters

        employees = employees.Take(amount);
        
        _appState.LastEmployeeId = employees.Last().EmpNo;
        
        return employees.ToList().Select(e => new EmployeeView(
            FirstName: e.FirstName,
            LastName: e.LastName,
            IsMale: e.Gender == "M",
            DepartmentName: _departmentService.GetDepartmentName(e.EmpNo),
            JobTitle: _titleService.GetTitleName(e.EmpNo),
            Salary: _salaryService.GetSalaryValue(e.EmpNo)
        ));
    }

    public IEnumerable<EmployeeView> GetEmployees()
    {
        var amount = _appState.ItemsPerPage;

        var lastId = _appState.LastEmployeeId ?? 0;
        
        var employees = _context.Employees
            .AsNoTracking()
            .OrderBy(e => e.EmpNo)
            .Where(e => e.EmpNo > lastId);

        #region filters
        if (_appState.GenderFilter.GetAllowedValue(out var allowedGender))
            employees = employees.Where(e =>
                e.Gender[0] == allowedGender);

        if (_appState.DepartmentFilter.GetAllowedValue(out var allowedDepartment))
            employees = employees.Where(e =>
                _departmentService.GetDepartmentName(e.EmpNo) == allowedDepartment);

        if (_appState.SalaryFilter.GetAllowedValue(out var allowedSalary))
            employees = employees.Where(e =>
                _salaryService.GetSalaryValue(e.EmpNo) >= allowedSalary.From &&
                _salaryService.GetSalaryValue(e.EmpNo) <= allowedSalary.To);
        #endregion filters

        employees = employees.Take(amount);
        
        _appState.LastEmployeeId = employees.Last().EmpNo;
        
        return employees.ToList().Select(e => new EmployeeView(
            FirstName: e.FirstName,
            LastName: e.LastName,
            IsMale: e.Gender == "M",
            DepartmentName: _departmentService.GetDepartmentName(e.EmpNo),
            JobTitle: _titleService.GetTitleName(e.EmpNo),
            Salary: _salaryService.GetSalaryValue(e.EmpNo)
        ));
    }

This code works perfectly fine unless i activate filters. I get an exception that ef core can't translate my shitty Linq to SQL and that's kinda understandable. But the question is, how can I make this work? Afaik loading all entities to list, filtering and then taking, for example 50 entities isn't a good idea.

19 replies

CC#

•Created by Sernik on 10/24/2022 in #help

Await Linq Expression

9 replies

CC#

•Created by Sernik on 10/17/2022 in #help

Deserialize JSON to dynamic object without Newtonsoft.Json

Hi, is there a way to deserialize json object to dynamic in .net? ideally from HttpContent. I don't want to use additional dependency, but i can't find vanilla solution. Thanks for help!

40 replies

CC#

•Created by Sernik on 10/17/2022 in #help

Get data from api periodically

Hi everyone, I am making a blazor server web app, and i have to get data from api every 10 seconds and save it to database and update index.razor page with that data. The question is, how can i get that data? I have to create service with timer and add it to services in program.cs? and which timer should i use? Thanks for help!

5 replies

CC#

•Created by Sernik on 10/6/2022 in #help

Collapse|Expand all nodes in tree

5 replies

CC#

•Created by Sernik on 8/16/2022 in #help

regex help [Answered]

So I made a regex with little help of copilot, it looks like this:

^
(?<source>[0-7],[0-7])\s?
(?<destination>[0-7],[0-7])\s?
(?<capture>[0-7],[0-7])?
$

^
(?<source>[0-7],[0-7])\s?
(?<destination>[0-7],[0-7])\s?
(?<capture>[0-7],[0-7])?
$

It should match strings like this: "n,n > n,n x n,n" or like this: "n,n > n,n", where n is number between 0 and 7 (spaces between are optional) However when I test it here https://regex101.com/r/MMnQql/1 I get no matches The question is why? Can somebody help me?

14 replies

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