Entity Framework Code First: Column Mapping

c# ef-code-first entity-framework

Question

I'm having trouble trying to map my EF 4.1 Code First model to a database. Everything works fine when the database match the code exactly, but when I try and map when the columns differ in name then I am running into issues.

I was following a tutorial that must've been built with one of the CTP builds because some of the methods are missing/different.

My model looks like:

public class Dinner
{
    public int DinnerID { get; set; }  
    public string HostedBy { get; set; }
    public DateTime EventDate { get; set; }
    public string Title { get; set; }
    public string Address { get; set; }
}

public class NerdDinners : DbContext
{
    public DbSet<Dinner> Dinners { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // THIS IS WHAT I TRIED BUT IT IS FAILING
        modelBuilder.Entity<Dinner>().Map(mc =>
            {
                mc.Properties(c => new {
                    colID = c.DinnerID,
                    colTitle = c.Title,
                    colHost = c.HostedBy,
                    colDate = c.EventDate,
                    colAddress = c.Address
                });
                mc.ToTable("tblDinner");
            }
        );
    }
}

I want my table to be:

tblDinners  
    colID  
    colHost  
    colDate  
    colTitle  
    colAddress  

I am getting this error:

The properties expression 'c => new <>f__AnonymousType0`5(colID = c.DinnerID, colTitle = c.Title, colHost = c.HostedBy, colDate = c.EventDate, colAddress = c.Address)' is not valid. The expression should represent a property: C#: 't => t.MyProperty' VB.Net: 'Function(t) t.MyProperty'. When specifying multiple properties use an anonymous type: C#: 't => new { t.MyProperty1, t.MyProperty2 }' VB.Net: 'Function(t) New From { t.MyProperty1, t.MyProperty2 }'.

What is the proper syntax to map the columns?

Bonus Points if you let me know how to map the Address Property into a subclass called Address:

public class Address
{
     City
     State
     Zip, etc
}
1
37
10/10/2014 7:16:28 PM

Accepted Answer

I believe you just have to do

modelBuilder.Entity<Dinner>().Property(x => x.HostedBy).HasColumnName("colHost");

for all of your columns that you want the db column names to be named differently than their property names.


Edit: After some more searching I came across this question. Judging from that and the error you posted, it seems like the mc.Properties() is more for splitting values into different tables, not to actually rename those table names. I think renaming will still have to be done on a manual basis.

This is again information from googling and I have no idea if I am just missing a piece to do exactly what you want :).

52
5/23/2017 12:02:17 PM

Popular Answer

How about using DataAnnotations?

[Key]
[Column("ColID", TypeName="int")]
public int DinnerID { get; set; }  

You can find a full list with samples at http://msdn.microsoft.com/en-us/data/gg193958



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