使用Entity Framework为多个表播种

Question

I have a meeting entity and a users entity which have a many to many relationship.

I'm using Autopoco to create seed data for the Users and meetings How do i seed the UserMeetings linking table that is created by EntityFramework with seed data?

The linking table has two fields in it; User_Id, and Meeting_ID.

I'm looping through the list of users that autopoco creates and attaching a random number of meetings

Here's what i've got so far.

 foreach (var user in userList)
        {

            var rand = new Random();

            var amountOfMeetingsToAdd = rand.Next(1, 300);

            for (var i = 0; i <= amountOfMeetingsToAdd; i++)
            {
                var randomMeeting = rand.Next(1, MeetingRecords);

                //Error occurs on This line
                user.Meetings.Add(_meetings[randomMeeting]);
            }

        }

I got an 'Object reference not set to an instance of an object.' even though the meeting record that i'm trying to attach does exist.

For info all this is happening prior to me saving the context to the DB.

Answer 1

There are 4 things on that line that could theoretically be null that would give you that error:

• user
• Meetings
• _meetings
• randomMeeting

try putting some if statements in front to check for null values.

My guess would be that it is _meetings that is null, but that is just a guess.