Entity Framework and Data binding

Question

I have two tables that are built using codefirst entity framework.

public class TimeEntry:Entity
{
    [Required]
    [Display(Name = "Activity")]
    public int ActivityId { get; set; }

    public virtual Activity Activity { get; set; }  
}

public class Activity:Entity
{
    private ICollection<TimeEntry> _timeEntries;


    [Required]
    public string Description { get; set; }

    public virtual ICollection<TimeEntry> TimeEntries
    {
        get
        {
            return _timeEntries ?? (_timeEntries = new List<TimeEntry>());
        }
        set
        {
            _timeEntries = value;
        }
    }
}
public class Entity
{
    public int Id { get; set; }
}

These are the classes I have created for my Db. There is no problem with creating the database. When I try to perform CRUD operations I get the error

DataBinding: 'System.Data.Entity.DynamicProxies.Activity_AD12BF558F098271F1F51B3B1489B4B3B281FD0B686C8457333DE5BEE0E8B6A9' does not contain a property with the name 'ActivityId'

It is trying to find ActivityId in the Activity table however the primary key is Id. How do I map the foreign key ActivityId in the TimeEntry table to the primary key Id in the Activity table.

Kamyar · Accepted Answer · 2012-08-14 15:25:32Z

You can use fluent api to let EF know about you mappings.

public class ActivityMap : EntityTypeConfiguration<Activity>
{
    public ActivityMap()
    {
         this.HasKey(a => a.Id);
    }
}

public class TimeEntryMap : EntityTypeConfiguration<TimeEntry>
{
    public TimeEntryMap()
    {
        this.HasKey(t => t.Id);
        // Relationships
        this.HasRequired(t => t.Activity)
            .WithMany(t => t.TimeEntries)
    }            .HasForeignKey(d => d.ActivityId);
}

Then in your context:

public class MyDbContext : DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new ActivityMap());
        modelBuilder.Configurations.Add(new TimeEntryMap());
    }
}

I think this will solve your issue.

Also, (as a side note) instead of defining _timeEntries, you can use auto implemented property for TimeEntries and initialize it in you ctor. like below:

public class Activity:Entity
{
    public virtual ICollection<TimeEntry> TimeEntries { get; set; }
    public Activity()
    {
        this.TimeEntries = new List<TimeEntry>();
    }
}

Fadi · Accepted Answer · 2014-07-05 15:27:16Z

1

hi i have the same problem

If one specifies DataKeyNames property as ID and the actual column name is CustomerID. It will throw the above error.
If one specifies DataTextField or DataValueField property as ID and the actual column name is CustomerID. It will throw the above error.

and found the answer here it work for me link

answered Jul 5, 2014 at 15:27

Fadi

2,3809 gold badges43 silver badges79 bronze badges

Comments

Community · Accepted Answer · 2017-05-23 12:06:36Z

0

If you are using Code First, you need to indicate the mapping of ActivityId => Id by overriding OnModelCreating in your DbContext.

At a suggestion, it seems you are mixing the concerns of DTO and MVC ViewModel in the same entity. Why not separate these concerns into 2 different entities?

edited May 23, 2017 at 12:06

CommunityBot

11 silver badge

answered Aug 14, 2012 at 15:28

StuartLC

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