How map single entity with multiple table

Question

I want to get data from two tables with single Entity class. How??

public class HomeViewModel  
{ 
    [Key] 
    [Column(\"candidate_ID\")] 
    public int cand         


        

Answer 1

This is called entity splitting. To make it work your CandidateID must be primary key in both tables and foreign key in the second table (entity splitting works only with one-to-one relations in a database).

Edit: There is another limitation. Entity splitting doesn't allow optional relations. Records in both tables must exists to make this work so if your table2 records are optional you must map both tables separately and construct your view model in the application from loaded records.

Answer 2

If you are suggesting that Table2 merely holds a foreign key to table1, but has a different primary key, then you can't really do what you're asking. Simply holding a foriegn key means that's a one to many relationship, and there's no way to map a single entity across a one to many relationship like that (even if your data only contains one record, the model relationship type is still one to many)

If you mean that Table2 has a primary and foreign key of candidate_id (and thus it's a 1 to 1 mapping) then you can map them into a single entity fairly easily using Inheritence described here:

http://weblogs.asp.net/manavi/archive/2010/12/28/inheritance-mapping-strategies-with-entity-framework-code-first-ctp5-part-2-table-per-type-tpt.aspx

If all you want is to create a single object that contains data from two tables, then that's a relatively simple linq query, which i won't get into because I really don't know exactly what you're looking for here.

Answer 3

Check data in daatbase table first.
It is because you might not have related data in table2. i.e table1 primary key value (which is candidate_id) is not present in table2 foreign key candidateID...