EF Core 6 - The instance of entity type 'AppCase' cannot be tracked because another instance with the same key value for {} is already being tracked - asp.net-core

Question

I'm using ASP.NET Core 6, and EF Core 6, and Repository/UnitOfWork pattern. I have some trouble with my project, The error "The instance of entity type 'AppCase' cannot be tracked because another instance with the same key value for {} is already being tracked" have throwed when I call UpdateAsync in Repository.
I think i know the issue description, and I used AsNoTracking() but the issue can't have been solved yet.
How can I solve it, please.
Thanks for your support and sorry for my bad English!
Here is my source code:
//MicroOrderBusiness.cs
public async Task<dynamic> CreateOrder(MicroOrderRequest requsetObject, string caseNo)
{
string processCode = "CEC1D433-C376-498B-8A80-B23DC3772024";
var caseModel = await _appCaseBusiness.PrepareAppCase(processCode, caseNo);
if (caseModel == null)
throw new Exception("Create request faield!");
var appCaseEntity = await _appCaseBusiness.AddNewCase(caseModel); // => Add new Case by using EF 6 Core via Repository and UnitOfWork**
if (appCaseEntity == null)
throw new Exception("Adding faield!");
var taskResponse = await _processTaskBusiness.ExecuteTask<MicroOrderRequest>(caseModel.FirstTaskCode, requsetObject);
if (Equals(taskResponse, null))
throw new Exception("Response task is not found!");
caseModel.CaseObjects.Add(taskResponse);
// Update case state
appCaseEntity.State = STATE.DONE;
appCaseEntity.CaseObject = JsonConvert.SerializeObject(appCase.CaseObjects);
var updateCase = await _appCaseRepository.UpdateAsync(appCaseEntity); // => Error throw here**
if (updateCase == null)
throw new Exception($"Update state case faiedl!");
return caseModel;
}
//Program.cs
builder.Services.AddDbContext<AppDbContext>(options =>
options.UseOracle(connectionString,
o => o.MigrationsAssembly(typeof(AppDbContext)
.Assembly.FullName)
.UseOracleSQLCompatibility("12")));
builder.Services.AddScoped(typeof(IUnitOfWork), typeof(AppDbContext));

Answer 1

The error has been explained in the document:https://learn.microsoft.com/en-us/ef/core/change-tracking/identity-resolution#attaching-a-serialized-graph
I checked your codes, I think the error may caused by:
tracking a serialized graph of entities
appCaseEntity.CaseObject = JsonConvert.SerializeObject(appCase.CaseObjects);
var updateCase = await _appCaseRepository.UpdateAsync(appCaseEntity); // => Error throw here**
You could learn more details and found the solution in this part
reusing a DbContext instance for multiple units-of-work
var appCaseEntity = await _appCaseBusiness.AddNewCase(caseModel);
........
var updateCase = await _appCaseRepository.UpdateAsync(appCaseEntity);
You registed the dbcontext as below(the lifetime is scoped by default):
builder.Services.AddDbContext<AppDbContext>(options =>
options.UseOracle(connectionString,
o => o.MigrationsAssembly(typeof(AppDbContext)
.Assembly.FullName)
.UseOracleSQLCompatibility("12")));
You could try to set the lifetime with Trasident or Use DbContextFactory to create different instance in different units of work
builder.Services.AddDbContext<AppDbContext>((options=>........),ServiceLifetime.Transient)
Check this document about using DbContextFactory
If you have further issue on this case,please provide the minimal codes that could reproduce the error