Nested Models in .Net Entity Framework

Question

Trying to get my head around Entity Framework. I have a database with two tables containing information on transactions. One contains transaction category information and is linked 1-to-1 into the transaction table (transactions.Category <=> Category.CategoryID). I can create new transactions in memory with the category entity filled but when I try to flush to DB I get "{"Invalid object name 'mEconomyUser.category'."}"

Transactions table:

TransactionID   uniqueidentifier
UserID      uniqueidentifier
Date        date
Text        nvarchar(250)
Category    uniqueidentifier
Amount      decimal(18, 0)

Category Table:

CategoryID  uniqueidentifier
UserID      uniqueidentifier
Text        nvarchar(50)

Here are my models:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;

namespace mEconomy.Models
{
    [Table("transactions", Schema = "mEconomyUser")]
    public class Transaction
    {
        [Key]
        public Guid TransactionID { get; set; }
        public Guid UserID { get; set; }
        public DateTime Date { get; set; }
        public string Text { get; set; }
        public virtual Category Category { get; set; }
        public decimal Amount { get; set; }
    }


    public class TransactionDBContext : DbContext
    {

        public DbSet<Transaction> Transactions { get; set; }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;

namespace mEconomy.Models
{
    [Table("category", Schema = "mEconomyUser")]
    public class Category
    {
        [Key]
        [ForeignKey("Transaction")]
        public Guid CategoryID { get; set; }
        public Guid UserID { get; set; }
        public String Text { get; set; }

        public virtual Transaction Transaction { get; set; }
    }

    public class CategoryDBContext : DbContext
    {

        public DbSet<Transaction> Categorys { get; set; }
    }
}

Any suggestions?

Answer 1

Thank you everybody for pushing me in the right direction! I now sorted all the issues with my code. Almost a little embarrassing but this was my very first encounter with EF. So this is what I ended up with:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;

namespace mEconomy.Models
{
    [Table("Transactions", Schema = "mEconomyUser")]
    public class Transaction
    {
        [Key] // Define primary-key
        public Guid TransactionID { get; set; }
        public Guid UserID { get; set; }
        public DateTime Date { get; set; }
        public string Text { get; set; }
        public decimal Amount { get; set; }

        [Column("Category")] // Column name of the database foreign key is named Category, want to use that name for the Model
        public Guid? CategoryID { get; set; } // Property to store the foreign key for the Category
        [ForeignKey("CategoryID")] // Define property that holds the foreign key for the category model/object
        public virtual Category Category { get; set; }
    }

    [Table("Categorys", Schema = "mEconomyUser")]
    public class Category
    {
        [Key] // Define primay-key
        public Guid CategoryID { get; set; }
        public Guid UserID { get; set; }
        public String Text { get; set; }

        public virtual ICollection<Transaction> Transactions { get; set; }
    }

    public class TransactionDBContext : DbContext
    {

        public DbSet<Transaction> Transactions { get; set; }
        public DbSet<Category> Categorys { get; set; }
    }
}

Okej a quick rundown of the problems I had.

As GertArnold pointed out, copy & past error! I had two DbSets of type Transaction instead of one each as above.

Two make sure that the code understands the one-to-many, or one-category-to-many-transactions, connection I had to add a ICollection of Transactions on the Category model.

On the transaction option there where nowhere to store the foreign key for the categoy model. I added a Guid (CategoryID) to store it in.

The EF tried to find a Column named Category_CategoryID in the Transactions table to store the foreign key for the corresponding Category entry. Since I used a database already in existence I had to use data annotations to set the Column for the CategoryID field.

I had to do the CategoryID Guid? or nullable. Otherwise all transactions that didn't have a Category would try to add a category into the database with GUID = 000-000.... Witch gave me a primary key constraint error.

And yes I know that Categories are miss spelled... done the same mistake since high-school.

The information you guys provided me with gave me a better understanding of EF so I was able to Google the right words. Found an blog series from a user here that really helped me get into it! - Thanks Morteza Manavi for the great input!