.Net core/EF : cannot access a disposed object. A common cause of this error is disposing a context

Question

I am using Net core, and am facing this famous problem i have this sample :

var model = await context.MethAppointementsPreventifs .FirstOrDefaultAsync(item => item.StartDate >= DateTodelete && item.IdOperation == XpertHelper.IdOperation); if (model != null) { var OpInfos = await context.MethOperations.AsNoTracking() .FirstOrDefaultAsync(item => item.Idoperation == model.IdOperation); context.MethAppointementsPreventifs.Remove(model); await context.SaveChangesAsync(); }

when i get my "model" and "OpInfos" no context disposed or excpetion thrown but in the line of :

context.MethAppointementsPreventifs.Remove(model);

it throws that exception, my methode doesnt return an async void :

public static async Task<int> ClearAppPreventif(KBFsteelContext context) { //clear from the day of intervention var DateTodelete = XpertHelper.DateIntervention; bool IsStill = true; while (IsStill) { var model = await context.MethAppointementsPreventifs .FirstOrDefaultAsync(item => item.StartDate >= DateTodelete && item.IdOperation == XpertHelper.IdOperation); if (model != null) { var OpInfos = await context.MethOperations.AsNoTracking().FirstOrDefaultAsync(item => item.Idoperation == model.IdOperation); context.MethAppointementsPreventifs.Remove(model); await context.SaveChangesAsync(); if (OpInfos.Unité == 1) { var newDayDate = DateTodelete.AddDays(OpInfos.Fréquence); DateTodelete = newDayDate; }//jours if (OpInfos.Unité == 2) { var newDayDate = DateTodelete.AddMonths(OpInfos.Fréquence); DateTodelete = newDayDate; }//Mois if (OpInfos.Unité == 3) { var newDayDate = DateTodelete.AddYears(OpInfos.Fréquence); DateTodelete = newDayDate; }//Annees } else { IsStill = false; } } return 1; }

and am calling it with await... so what should i do ?

Serge · Accepted Answer · 2021-01-26 12:44:11Z

1

Maybe your OpInfos is getting destroyed. Especially if you have a cascade delete behavior. Why you don't change your code to this:

....your code if (model != null) { var operationId=model.IdOperation: context.MethAppointementsPreventifs.Remove(model); var result = await context.SaveChangesAsync(); if (result==0) return 0; //error var OpInfos = await context.MethOperations.AsNoTracking().FirstOrDefaultAsync(item => item.Idoperation ==operatonId); if(OpInfos ==null) return 0; //error if (OpInfos.Unité == 1) ....continue your code

edited Jan 26, 2021 at 12:44

answered Jan 26, 2021 at 12:29

Serge

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5 Comments

Kessar Mohamed Over a year ago

when i changed it like so, "context.MethAppointementsPreventifs.Remove(model)" works fine and the "operationId"is correct , but in the "await context.SaveChangesAsync()" it throws the exception

Serge Over a year ago

Yes, dbcontext never throws exception at Remove(model), only at SaveChanges(). Did you try my code. You can get some more info from it.

Kessar Mohamed Over a year ago

Yes, but i had the same exception so i tried to get "OpInfos" between "Remove(model)" and "SaveChanges()" to check my context but i got the same exception on "OpInfos" too

Serge Over a year ago

Can you show MethOperations and MethAppointementsPreventifs classes please. It is hard to undestand what are trying to accomplish.

Kessar Mohamed Over a year ago

I solved it, in fact this methode was deep in the call stack, i had one of the methodes async void, so i had to make all of the methodes in the call stack async Task not just this one

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