help help Why is Entity Framework 5.0 inserting duplicate records in the Database in uncertain behavior when using AddAsync() method for adding data. enter image description here

CodePudding user response：

You are checking for null in your list. However a .Where() query will return an empty enumerable and not null when it doesn't find any results.

To fix this issue you have to check the count.

   var exist = await context.Where(x => x...)
   if(exist == null || exist.Count() == 0) 
   {
      add purchase here
   }

CodePudding user response：

The problem here is that the AddAsync function sends two records to the database for registration