DEV Community: Rahmat Al Hakam

Okay, maybe, vibe coding is not bad at all

Rahmat Al Hakam — Sun, 14 Dec 2025 07:14:31 +0000

Hanya Sekali Klik! Cara Scraping Data Produk Toko di Tokopedia yang Paling Simpel

Rahmat Al Hakam — Sat, 11 Jan 2025 05:58:00 +0000

Fitur

Pencarian berdasarkan input keyword.
Multiple url sekali klik.
Import otomatis ke csv.
Fitur retry jika terjadi error connection.
Ambil data nama toko, produk, harga, rating, penjualan, url product, dan gambar produk.

Screenshot

Gambar 1: Kodingan Tokopedia Scraper dengan Python

Gambar 2: Hasil Running Script

Gambar 3: Data Hasil Scraping

Cara Penggunaan

Download dan install python3 di OS kamu jika belum menginstall. Cek: Download pyhton
Clone atau download repository tokped scraper via.
git clone https://github.com/rahmatalhakam/tokopedia-scraper.git
Install library python yang dibutuhkan.
pip install requests beautifulsoup4 pandas
Setting keyword pencarian di file config.json
```
{
    "keyword": "mouse b100"
}
```

Tambahkan url toko yang ingin di file tokopedia_shops.csv. Contoh:

url
https://www.tokopedia.com/elscomputer
https://www.tokopedia.com/starcomporigin
https://www.tokopedia.com/youngscom/
https://www.tokopedia.com/anandamcomputer
https://www.tokopedia.com/computajogja
https://www.tokopedia.com/harrismajogja
https://www.tokopedia.com/jabenjogja

run script pyhon di dengan cara
python tokpedscraper.py

Note

Jika script ini bermanfaat dan memang digunakan, request fitur baru dapat saya pertimbangkan. Jangan lupa like, follow, dan komen di bawah. Kira-kira fitur apa yang perlu didevelop. Terimakasih. 😃

Transforming Enumerable into Queryable with Linq: A How-To Guide on Concat, Union, and Troubleshooting EF Core 6 Errors

Rahmat Al Hakam — Tue, 04 Apr 2023 15:46:49 +0000

When we write the linq code that use set operation (concat, union,intersect), sometimes we get many errors. After we search the error, usually we just change from queryable to enumerable. That solution is just fine, but we also must know the difference between enumerable and queryable. Enumerable would call database twice when we use the set operation, but when we use queryable we only call database once. This will impact the performance.

I have listed 3 common errors when we use set operation on linq. Each error has a different solution. I will explain it in an error-solution order.

Error

System.InvalidOperationException: Unable to translate set operation when matching columns on both sides have different store types.

Solution

From



select new 
{
  Description = x.Description
}



select new 
{
  Description = Convert.ToString(x.Description)
}

You should change varName to Convert.ToString(varName) on property that has different Max Length. Don't use varName.ToString() method. Why? Because Convert.ToString(varName) will be converted to CONVERT(NVarChar(MAX),table_name.column_name) on SQL Server and table_name.column_name::text on PostgreSQL.

Code Example:

More Info: https://github.com/dotnet/efcore/issues/19129

Error

System.InvalidOperationException: Unable to translate set operation after client projection has been applied. Consider moving the set operation before the last 'Select' call.

Solution

From



var a = 
( 
  from x in _dbContext.TableNameA
  select new 
  {
    Date = x.Description.ToString("dd/MM/yyyy")
  }
).AsQueryable();

var b = 
( 
  from x in _dbContext.TableNameB
  select new 
  {
    Date = x.Description.ToString("dd/MM/yyyy")
  }
).AsQueryable();

var result = a.Concat(b).ToList();



var a = 
( 
  from x in _dbContext.TableNameA
  select new 
  {
    Date = x.DateDoc
  }
).AsQueryable();

var b = 
( 
  from x in _dbContext.TableNameB
  select new 
  {
    Date = x.DateDoc
  }
).AsQueryable();

var result = a.Concat(b)
  .Select(x=> new 
  {
    Date = x.Date.ToString("dd/MM/yyyy") 
  })
  .ToList();

You should check all interpolated string on Select call method on linq. Interpolated string will cause the error because interpolated string is client evaluation. Rewrite the interpolated string after union or concat method. Example of interpolated string

varName.ToString()
varName.ToString("dd/MM/yyyy")
varName1 + " " + varName2
$"{varName.Trim()} - {varName.Trim()}")

Code Example:

More Info: https://github.com/dotnet/efcore/issues/16243

Error

System.InvalidOperationException: Unable to translate a collection subquery in a projection since either parent or the subquery doesn't project necessary information required to uniquely identify it and correctly generate results on the client side. This can happen when trying to correlate on keyless entity type. This can also happen for some cases of projection before 'Distinct' or some shapes of grouping key in case of 'GroupBy'. These should either contain all key properties of the entity that the operation is applied on, or only contain simple property access expressions.

Solution

From



var result = a.Concat(b)
  .GroupBy(x => x.Code)
  .Select(x => new
  {
    Code = x.Key,
    ListDoc = x.ToList()
  }
  );



var result = a.Concat(b)
  .ToList()
  .GroupBy(x => x.Code)
  .Select(x => new
  {
    Code = x.Key,
    ListDoc = x.ToList()
  }
  );

Check any ToList() on select call method in Linq. Add ToList() method before GroupBy or Distinct call.

Code Example:

More Info: https://github.com/dotnet/efcore/issues/16243

Play, Run, And Debug Yourself

If you want to play with this error, you can go to my github repo. I made a simple web api that you can use to understand this article deeper. Below is the screenshot of the endpoint that you can try.

After you run the server, you can open https://localhost:7080/swagger/index.html and run the /Transaction/GetReportQueryableErrorRunTime endpoint. Then, check what will happen. Happy coding! 😊😊😊

Sharing Story of My Former Team Lead

Rahmat Al Hakam — Thu, 09 Feb 2023 02:31:42 +0000

Hello everyone, i just wanna share my thoughts about my ex former team leader in my current company. This story is about what I felt as a Junior Backend Developer when he led the team.

The Story

I feel my leader is a kind of a protector for developers. For the real example, he always makes sure the feature that will be developed is clear, very detailed, and easy to understand. If the feature is not ready or the requirement is still ambiguous, he won’t give that feature to the dev. Even though there is only a little mistake on the UI, my lead asks the Business Process Analyst (BPA) or the UI Team to fix it first.
One day, the users ask for an additional feature after going live. They ask the estimation time to develop is a maximum of only 2-3 working days. I know that 3 days is more than enough but my leader is mad and of course disagrees. My leader told me that at least the team needs 1 week to develop. I don’t know exactly the reason, but after that i feel safe and more comfortable when he leads the team.
Fyi, when i joined the team, i was a fresh graduate that didn't have much experience about BE development. So sometimes I don't know what I should do to solve my work problem. And again, my leader is very welcome about that. For only 1 year, I worked with him, I feel my experience in BE development is growing exponentially. Hahaha. I learned from him about the clean code, the simple query, the optimum query, and much more. I feel empowered.
Okay, for this section, it may not sound like it doesn't make sense at all, but it was real. My leader can fix bugs as fast as you blink your eyes. I mean, if the Quality Assurance team finds a bug and tells me to check what's the problem, maybe I need more than 2 hours to only know the root causes (only know the problem, not know how to fix it). But, magically, he only needs maybe like 10 minutes to fix the bugs. Amazing!.

Why do I respect him so much?

He spent time helping with all the work, not only development but also fixing bugs, answering BPA questions, etc even when one of his parents died (first thing first, I share this with all my respect to him). His commitment and dedication for the team is beyond my expectation.
A simple behavior like answering my chat after working hours, even on saturday or sunday. For some people it seems not polite to chat, but he didn't mind at all just to make sure I didn't have any technical issues.
He always appreciates, says sorry, and thank you, three magic words that can make a big difference. It really changed the culture of the team so we all felt safe, enjoyed, and happy all the time even though going through hard times.
His guidance, support, and mentorship have been instrumental in shaping my professional development career and I am truly grateful for the opportunities he provided me with.

And finally we can only just say thank you, thank you very much for the lessons we learned and the memories we made while working with you. I wish you all the best in your future endeavors and I hope our paths cross again in the future.

**_The One And Only Koh/Mr/Pak Ronny_**

If you have another story with Ko Ronny, feel free to share your experience in the comment section below.

Cara Memuat Global Custom Error Filter GraphQL di Hot Chocolate .NET Platform

Rahmat Al Hakam — Mon, 12 Dec 2022 15:53:07 +0000

Permasalahan Error di Hot Chocolate

Saat mengembangkan sistem menggunakan Framework Hot Chocolate, kita pasti akan menemukan masalah berupa response error setelah melakukan request query ke sistem. Error yang ditampilkan tidak informatif sehingga sering membuat bingung letak permasalahan utamanya. Berikut contoh default error yang akan ditampilkan.

{
    "errors": [
        {
            "message": "Unexpected Execution Error",
            "locations": [
                {
                    "line": 11,
                    "column": 2
                }
            ],
            "path": [
                "upsertStudent"
            ]
        }
    ]
}

Response error hanya menampilkan pesan "unexpected execution error". Response ini tidak informatif karena kita tidak mengetahui penyebab utama atau root cause error tersebut. Kita hanya punya informasi nama query yang membuat error yaitu upsertStudent, tapi tidak tahu line code mana yang menyebabkan error tersebut terjadi. Oleh karena itu, kita perlu menghandle dengan cara membuat custom error filter agar error yang ditampilkan informatif dan dapat dimengerti oleh frontend web atau mobile.

Pendekatan Pemecahan Permasalahan

Ada beberapa cara yang bisa digunakan untuk mengatasi masalah di atas. Beberapa solusi yang bisa digunakan:

1. Menampilkan Detail Error di Response

Solusi ini sebenarnya tidak cocok digunakan untuk production environment karena menampilkan pesan error secara gamblang. Gunakan solusi ini hanya untuk development saja. Berikut codenya:

services.AddGraphQLServer()
        .RegisterDbContext<AppDbContext>()
        ....
        .ModifyRequestOptions(opt => opt.IncludeExceptionDetails = env.IsDevelopment());

Penambahaan opsi IncludeExceptionDetails dengan nilai true (jika env = development), maka akan memunculkan detail error. Berikut contoh hasil responsenya.

{
    "errors": [
        {
            "message": "Unexpected Execution Error",
            "locations": [
                {
                    "line": 20,
                    "column": 2
                }
            ],
            "path": [
                "removeStudent"
            ],
            "extensions": {
                "message": "Sequence contains no elements.",
                "stackTrace": "
at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.SingleAsync[TSource](IAsyncEnumerable`1 asyncEnumerable, CancellationToken cancellationToken)\r\n 
.... 
at ManajemenTugasAkhirGeologi.GraphQL.Students.Services.Implementations.StudentService.RemoveStudent(Guid studentId, CancellationToken cancellationToken) 
in ... 
\\GraphQL\\Students\\Services\\Implementations\\StudentService.cs:line 55 .... ...."
            }
        }
    ]
}

Hasil response tersebut menampilkan error yang sebenarnya yaitu "sequence contains no element" pada file StudentService.cs line 55. Dari detail stack trace tersebut dapat disimpulkan bahwa data yang dicari tidak ditemukan dalam database.

Solusi ini tidak cocok untuk production karena pesan errornya masih sangat general, oleh karena itu kita bisa melakukan custom error filter agar pesan error yang ditampilkan sesuai dengan yang kita harapkan.

2. Global Custom Error Filter

Solusi ini dapat digunakan untuk mengcustom pesan error sesuai dengan keinginan kita. Hal pertama yang dilakukan adalah membuat class yang mengimplementasikan IErrorFilter dari HotChocolate library.

//implement IErrorFilter
public class GraphQLErrorFilter : IErrorFilter
{
    public IError OnError(IError error)
    {
        // BusinessLogicException adalah custom error
        if (error.Exception is BusinessLogicException)
        {
            return error.WithCode("BusinessLogic").WithMessage(error.Exception!.Message);
        }
        return error;
    }
}

Potongan code di atas menjelaskan class GraphQLErrorFilter yang mengimplementasikan IErrorFilter dari Hot Chocolate. Method OnError akan mengecek apakah error yang dihandle adalah BusinessLogicException, jika iya, maka akan menampilkan error sesuai dengan pesan yang ditulis pada saat throw exception. Selain itu, maka error akan dikembalikan tanpa ada perubahan. Kodingan custom exception sebagai berikut.

//custom class exception
public class BusinessLogicException : Exception
{
    public BusinessLogicException() { }

    public BusinessLogicException(string message) : base(String.Format(message)) { }
}

Code di atas menjelaskan tentang pembuatan class exception baru yang bernama BusinessLogicException yang merupakan turunan dari class Exception. Terdapat overloading constructor bernama BusinessLogicException yang bisa menerima 0 atau 1 parameter string message.

Hal selanjutnya yaitu mendaftarkan custom error filter pada Service Collection

services.AddGraphQLServer();
...
services.AddErrorFilter<GraphQLErrorFilter>();

Jika sudah ditambahkan maka custom exception sudah bisa digunakan. Contoh penggunaan custom exception sebagai berikut.

var student = await _dbContext.Students.SingleOrDefaultAsync(s => s.Id == studentId, cancellationToken);
if (student == null)
    //memanggil custom exception
    throw new BusinessLogicException($"id {studentId} tidak ditemukan");
_dbContext.Remove(student);
await _dbContext.SaveChangesAsync(cancellationToken);

Penggunaan custom exception akan tampil pada response error. Berikut contoh hasil akhir saat error terjadi.

{
    "errors": [
        {
            "message": "id 08dacddf-40f6-43cb-84d6-7c51795af961 tidak ditemukan",
            "locations": [
                {
                    "line": 20,
                    "column": 2
                }
            ],
            "path": [
                "removeStudent"
            ],
            "extensions": {
                "code": "BusinessLogic"
            }
        }
    ]
}

3. Tampilkan Error pada Log di Console

Solusi ketiga yang dapat dilakukan adalah menampilkan logging eror pada console setiap kali error terjadi. Framework Hot chocolate telah menyediakan class ExecutionDiagnosticEventListener. Terdapat banyak method yang dapat dioverride dari class tersebut, seperti ResolverError(), TaskError(), dan RequestError(). Berikut contoh code untuk menampilkan error di log console.

public class ErrorLoggingDiagnosticsEventListener : ExecutionDiagnosticEventListener
{
    private readonly ILogger<ErrorLoggingDiagnosticsEventListener> _log;

    public ErrorLoggingDiagnosticsEventListener(ILogger<ErrorLoggingDiagnosticsEventListener> log)
    {
        _log = log;
    }

    public override void ResolverError(IMiddlewareContext context, IError error)
    {
        _log.LogError(error.Exception, error.Message);
    }

    public override void TaskError(IExecutionTask task, IError error)
    {
        _log.LogError(error.Exception, error.Message);
    }

    public override void RequestError(IRequestContext context, Exception exception)
    {
        _log.LogError(exception, "RequestError");
    }
}

Setelah itu jangan lupa untuk menambahkan ErrorLoggingDiagnosticsEventListener pada Service Collection.

services.AddGraphQLServer()
        .AddDiagnosticEventListener<ErrorLoggingDiagnosticsEventListener>();

Setelah itu, console akan menampilkan error dan stack tracenya. Berikut contoh realnya.

fail: ManajemenTugasAkhirGeologi.ErrorFilters.ErrorLoggingDiagnosticsEventListener[0]
      Data mahasiswa tidak ditemukan
      ManajemenTugasAkhirGeologi.ErrorFilters.BusinessLogicException: Data mahasiswa tidak ditemukan
         at ManajemenTugasAkhirGeologi.GraphQL.Students.Services.Implementations.StudentService.RemoveStudent(Guid studentId, CancellationToken cancellationToken) in D:\manajementugasakhir\ManajemenTugasAkhirGeologi\GraphQL\Students\Services\Implementations\StudentService.cs:line 57
         at ManajemenTugasAkhirGeologi.GraphQL.Students.Mutations.StudentMutation.RemoveStudent(Guid studentId, IStudentService studentService, CancellationToken cancellationToken) in D:\manajementugasakhir\ManajemenTugasAkhirGeologi\GraphQL\Students\Mutations\StudentMutation.cs:line 23
         at HotChocolate.Resolvers.Expressions.ExpressionHelper.AwaitTaskHelper[T](Task`1 task)
         at HotChocolate.Types.Helpers.FieldMiddlewareCompiler.<>c__DisplayClass9_0.<<CreateResolverMiddleware>b__0>d.MoveNext()
      --- End of stack trace from previous location ---
         at HotChocolate.AspNetCore.Authorization.AuthorizeMiddleware.InvokeAsync(IDirectiveContext context)
         at HotChocolate.Utilities.MiddlewareCompiler`1.ExpressionHelper.AwaitTaskHelper(Task task)
         at HotChocolate.Execution.Processing.Tasks.ResolverTask.ExecuteResolverPipelineAsync(CancellationToken cancellationToken)
         at HotChocolate.Execution.Processing.Tasks.ResolverTask.TryExecuteAsync(CancellationToken cancellationToken)

4. Selesai 🔥

Nah itulah beberapa solusi yang bisa dicoba Dari ketiga solusi tersebut, saya lebih prefer untuk memakai cara yang kedua dan ketiga karena lebih cocok untuk dilakukan pada level production. Detail error seharusnya tidak boleh ditampilkan pada pihak luar karena berpotensi pada security risk atau celah keamanan.

Sekian dan Terimakasih

Jika artikel ini bermanfaat, bisa like, comment, dan share ya... 👍
Masukan, kritik, dan pertanyaan dapat disampaikan pada kolom komentar. Mantab, salam koding, dan terimakasih.

Referensi

Cara Membuat Soft Delete di Entity Framework Core dengan Global Query Filter

Rahmat Al Hakam — Thu, 08 Dec 2022 06:58:18 +0000

Permasalahan dan Business Requirement

Proses pembuatan sistem wajib hukumnya mengikuti business requirement yang telah ditentukan. Terkadang, requirement tersebut mewajibkan untuk tidak menghapus data secara permanen di database. Berbagai alasan menjadi pertimbangan, seperti

Tracing riwayat
Backup data
Lebih mudah debugging code (percaya ga percaya 🤣).

Pendekatan Pemecahan Permasalahan

Pendekatan yang dapat dilakukan adalah menggunakan metode soft delete. Metode ini sebenarnya hanya menyembunyikan data pada saat sistem berjalan dengan menambahkan flag true-false pada kolom IsDeleted di setiap table.

Metode Soft Delete dengan Global Query Filter

Step 1: buat base interface dan builder nya

Hal yang pertama dilakukan adalah membuat interface dan builder sebagai basis untuk model yang akan menerapkan fitur soft delete.
Buat file IEntityBase.cs dan IEntityBaseBuilder pada folder Models\EntityBases.

IEntityBase.cs

namespace SoftDeleteTutorial.Models.EntityBases;

public interface IEntityBase
{
    Guid Id { get; set; } //ditaruh di interface karena setiap model butuh Id
    bool IsDeleted { get; set; } //flagging utk soft delete
}

IEntityBaseBuilder.cs

namespace SoftDeleteTutorial.Models.EntityBases;
public interface IEntityBaseBuilder<TEntity> : IEntityTypeConfiguration<TEntity> where TEntity : class
{
}

Step 2: buat abstract model dan builder yang mengimplement interface

Lankah selanjutnya adalah membuat abstract basis model yang mengimplement interface pada step 1. Model yang akan dibuat adalah EntityBase.cs dan builder modelnya EntityBaseBuilder.cs.

EntityBase

namespace SoftDeleteTutorial.Models.EntityBases;

public abstract class EntityBase : IEntityBase //abstract class mengimplementasikan interface base
{
    public Guid Id { get; set; }
    public bool IsDeleted { get; set; }
}

EntityBaseBuilder

namespace SoftDeleteTutorial.Models.EntityBases;

public abstract class EntityBaseBuilder<TEntity> : IEntityBaseBuilder<TEntity> where TEntity : class, IEntityBase //implementasi base interface
{
    //konfigurasi global query filter
    public virtual void Configure(EntityTypeBuilder<TEntity> builder)
    {
        builder.HasQueryFilter(t => !t.IsDeleted); //filter data yang IsDeleted = 0 (false)
    }
}

step 3: cara menggunakan EntityBase pada Model

Cara penggunaannya cukup simple yaitu dengan mengimplementasi interface EnitityBase dan EntityBaseBuilder pada model yang ingin menggunakan fitur soft delete. Contoh, kita membuat model Student.cs dan StudentBuilder.cs. Simpan file tersebut pada folder Models\Entities.

Student.cs

namespace SoftDeleteTutorial.Models.Entities;

public class Student : EntityBase //implement dari abstract class
{
    //tidak perlu proprty Id karena sudah ada di EntityBase
    public string Name { get; set; } = string.Empty;
    public string Nim { get; set; } = string.Empty;
}

StudentBuilder.cs

namespace SoftDeleteTutorial.Models.Entities;

public class StudentBuilder : EntityBaseBuilder<Student> //implement EntityBaseBuilder utk class model yang diinginkan
{
    // override konfigurasi yang sebelumnya telah ada query filternya
    public override void Configure(EntityTypeBuilder<Student> builder)
    {
        base.Configure(builder);
        builder.Property(s => s.Name).HasMaxLength(100);
        builder.Property(s => s.Nim).HasMaxLength(10);
        builder.HasIndex(s => s.Nim).IsUnique();
    }
}

step 4: buat Ekstensi untuk tracking hapus data

Hal yang diharapkan saat soft delete adalah otomatis set IsDelete = true ketika ada penghapusan data. Kita tidak ingin setiap ada penghapusan data harus set IsDeleted=true. Oleh karena itu, kita perlu membuat ekstensi yang akan mentracking setiap penghapusan data. Kita beri nama ChangeTrackerExtensions.cs yang ditaruh pada folder Extentions.

ChangeTrackerExtensions.cs

using SoftDeleteTutorial.Models.EntityBases;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.ChangeTracking;

namespace SoftDeleteTutorial.Extensions;

public static class ChangeTrackerExtensions
{
    public static void SetAuditProperties(this ChangeTracker changeTracker)
    {
        changeTracker.DetectChanges();
        IEnumerable<EntityEntry> entities = changeTracker.Entries().Where
            (
                t =>
                t.Entity is IEntityBase
                && (t.State == EntityState.Deleted)
            );

        foreach (EntityEntry entry in entities)
        {
            IEntityBase entity = (IEntityBase)entry.Entity;

            if (entry.State == EntityState.Deleted)
            {
                entity.IsDeleted = true; //jika ada penghapusan data maka IsDeleted=true
                entry.State = EntityState.Modified;
            }
        }

    }
}

step 5: override method savechange di ApplicationDbContext

Beberapa method yang harus dioverride ada 4 yaitu

SaveChangesAsync(CancellationToken cancellationToken = default)
SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default)
SaveChanges()
SaveChanges(bool acceptAllChangesOnSuccess)

Method tersebut akan ditambah ekstensi ChangeTracker yang sudah dibuat pada step 4.

AppDbContext.cs

namespace SoftDeleteTutorial.Models;
public class AppDbContext 
{
    public AppDbContext(DbContextOptions options) : base(options)
    {

    }
    public DbSet<Student> Students { get; set; } = default!;

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        new StudentBuilder().Configure(modelBuilder.Entity<Student>());
    }

    public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
    {
        ChangeTracker.SetAuditProperties();
        return await base.SaveChangesAsync(cancellationToken);
    }

    public override async Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default)
    {
        ChangeTracker.SetAuditProperties();
        return await base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
    }

    public override int SaveChanges()
    {
        ChangeTracker.SetAuditProperties();
        return base.SaveChanges();
    }

    public override int SaveChanges(bool acceptAllChangesOnSuccess)
    {
        ChangeTracker.SetAuditProperties();
        return base.SaveChanges(acceptAllChangesOnSuccess);
    }
}

step 6: sudah selesai ❤️

Unique dan Index Coloumn

Jika menggunakan soft delete ada beberapa hal yang harus disesuaikan terutama untuk kolom yang unique atau berstatus index. Soft delete yang tidak menghapus secara fisik, artinya jika ada data baru yang ditambahkan dengan data yang sama bisa jadi kena error dulicate key. Contohnya, property Nim pada model Student adalah unique dengan data new Student {Name="Rahmat", Nim="123"}. Lalu dihapus tuh student atas nama Rahmat. Nah, jika ada data dengan Nim="123" maka akan error karena dianggap duplicate key. Oleh karena itu kita perlu mengecek ketika insert data Student dengan IgnoreQueryFilter(). Contoh kodingan seperti berikut.

private async Task<Student> InsertStudent(StudentInput input, CancellationToken cancellationToken)
    {
        //IgnoreQueryFilter() untuk mengambil semua data tanpa melihat flag IsDeleted.
        var student = await _dbContext.Students.IgnoreQueryFilters().SingleOrDefaultAsync(s => s.Nim == input.Nim, cancellationToken); 
        if (student != null && !student.IsDeleted)
            throw new BusinessLogicException($"NIM {input.Nim} sudah terdaftar. Silahkan daftar mahasiswa lainnya!");
        else if (student != null && student.IsDeleted)
        {
            student.IsDeleted = false; //*membangkitkan* yang sudah terhapus
            await _dbContext.SaveChangesAsync(cancellationToken);
            return student;
        }
        var newStudent = new Student { Name = input.Name, Nim = input.Nim };
        await _dbContext.Students.AddAsync(newStudent, cancellationToken);
        await _dbContext.SaveChangesAsync(cancellationToken);
        return newStudent;
    }

Saran dan Masukan

Jika terdapat pertanyaan pada artikel ini bisa bertanya di kolom komentar. Saya juga sangat menerima jika ada masukan dan kritik, siapa tahu anda bisa kasih saran yang lebih baik atau mendapati kesalahan code. Terimakasih semuanya 😊👍