Saving Data to Relational Database (Entity Framework)
- by sheefy
I'm having a little bit of trouble saving data to a database. Basically, I have a main table that has associations to other tables (Example Below).
Tbl_Listing
ID
UserID - Associated to ID in User Table
CategoryID - Associated to ID in Category Table
LevelID - Associated to ID in Level Table.
Name
Address
Normally, it's easy for me to add data to the DB (using Entity Framework). However, I'm not sure how to add data to the fields with associations. The numerous ID fields just need to hold an int value that corresponds with the ID in the associated table.
For example; when I try to access the column in the following manner I get a "Object reference not set to an instance of an object." error.
Listing NewListing = new Listing();
NewListing.Tbl_User.ID = 1;
NewListing.Tbl_Category.ID = 2;
...
DBEntities.AddToListingSet(NewListing);
DBEntities.SaveChanges();
I am using NewListing.Tbl_User.ID instead of NewListing.UserID because the UserID field is not available through intellisense.
If I try and create an object for each related field I get a "The relationship between the two objects cannot be defined because they are attached to different ObjectContext objects." error.
With this method, I am trying to add the object without the .ID shown above - example NewListing.User = UserObject.
I know this should be simple as I just want to reference the ID from the associated table in the main Listing's table. Any help would be greatly appreciated.
Thanks in advance,
-S
