Entity Framework: Attaching an entity of type 'MODELNAME' failed because another entity of the same type already has the same primary key value

Question

I found multiple posts for this issue, however my issue is little different and error shown is exactly matches to my scenario.

1. I have two different schema under by database. e.g. PreSchool.Students & School.Students. And per our requirements, rest is same for both Students tables, including primary key.

2. Now in my code, I am updating record of 'PreSchool.Students' using following code:

   var wouldBeUpdatedStudent = await context.Students
               .FindAsync(student.StudentIdentity).ConfigureAwait(false);
   wouldBeUpdatedStudent = student; //updated student object
   context.Entry(wouldBeUpdatedStudent).State = EntityState.Modified; // This line throws error 
   var result = await context.SaveChangesAsync().ConfigureAwait(false);
   

3. Under OnModelCreating I clearly set tableName & SchemaName for each of Entity. By this, I am expecting whenever I change entity/ model state, it should catch the correct table as per setting done under OnModelCreating. However this is not happening and throws exception.

I tried using context.Students.AsNoTracking() this works if no cascading to Students Entity. However, there are some cascading/children entities which are also same DDL. e.g. context.Student.Exams

Answer 1

Logically I didn't get answer which gives proper explanation -fix on this error. However This answer resolved my issue. One more think I observed with is solution is, if new object has exactly same values as per entity underlying database, it won't update table.

e.g.

context.Set<Student>().AddOrUpdate(wouldBeUpdatedStudent);
result = await context.SaveChangesAsync().ConfigureAwait(false);

Reason I cannot use AsNoTracking() because I have nested entities which are same across other schema. So Even if I use AsNoTracking() at top level entity, I get same error for child level. Same as I mentioned in my question.