Code-First generated database different from DbContext Model

Question

I've successfully setup a simple MVC4 internet app that stores model data onto a LocalDb v11.0 SQL server. I generated the database using a code-first approach, however, the Table fields in the database are different than the model database context.

public class Record
{
    public int Id { get; set; }
    public string PlantLocation { get; set; }
    public Plant PlantType { get; set; }
    public string Description { get; set; }
}
public class Plant
{
    public int Id { get; set; }
    public string Name { get; set; }
}
public class RecordContext : DbContext
{
    public DbSet<Record> Records { get; set; }
    public DbSet<Plant> Plants { get; set; }
}

dbo.Records Table 
[Id]            INT            IDENTITY (1, 1) NOT NULL,
[PlantLocation] NVARCHAR (MAX) NULL,
[Description]   NVARCHAR (MAX) NULL,
**[PlantType_Id]  INT            NULL,**

When i pull-up the table data, every field is populated correctly, with the PlantType_ID showing the Id of the selected Plant.

How am i supposed to used the PlantType_ID to display the ID of the Plant(or even use this stored data) in my View if PlantType_ID is not in my RecordContext?

I have tried the following to try an get at the ID but to no avail:

        @Html.DisplayFor(modelItem => item.PlantType.Id)

I'm not getting build errors or runtime errors if anyone is wondering. Any insight is appreciated.

Sean Kenny · Accepted Answer · 2013-06-07 07:42:51Z

Add virtual to the plant property to allow lazyloading:

public virtual Plant PlantType { get; set; }

To avoid N+1 issues, you can instruct EF to bring back the PlantType record as part of the same initial query. Something like:

var record = db.Records.Include("PlantType").First();

We have an extension method to make it a little nicer using lambdas:

var record = c.Records.Include(i => i.PlantType).First();

public static class Extensions
{
    public static IQueryable<T> Include<T, TProperty>(this IQueryable<T> source, Expression<Func<T, TProperty>> path) where T : class
    {
        return System.Data.Entity.DbExtensions.Include(source, path);
    }
}

Edit

Alternatively you could add the following property to the Record model if all you are after is the id:

public int PlantTypeId { get; set; }

Your database structure will largely stay the same (constraint names will change) except now you can change your razor syntax to be:

@Html.DisplayFor(modelItem => item.PlantTypeId)

You do not need to add the include comments now either.

aquaraga · Accepted Answer · 2013-06-07 05:56:34Z

0

If you want to display the plant name, you could directly use:

@Html.DisplayFor(modelItem => item.PlantType.Name)

answered Jun 7, 2013 at 5:56

aquaraga

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1 Comment

Pyrphoros Over a year ago

Sorry, i meant the ID. In my database, PlantType_ID =5 (for example). whenever i access PlantType.Name in my viewmodel, they are null. PlantType_ID is not a property of any of my classes yet it appears in my database as a value in the Record table. How can i use this?

Jalpesh Vadgama · Accepted Answer · 2013-06-07 06:01:55Z

0

You are using primary key for display for. That's why its not showing as above said you can use display for for plant type name and other fields.

answered Jun 7, 2013 at 6:01

Jalpesh Vadgama

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4 Comments

Pyrphoros Over a year ago

This is my Index controller : return View(db.Records.ToList()); Simply doing DisplayFor(...PlantType.Id(..or Name)) are both null, yet in the database i have PlantType_ID = 4.

Jalpesh Vadgama Over a year ago

Yes but why you need to display primary key ?

Pyrphoros Over a year ago

I am simply trying to access the plant stored in the database, but it is of type "plant", how can i grab this from the database?

Jalpesh Vadgama Over a year ago

display plant name with display for and use primary key for any link or anything

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