create a new table Entity framework code first pattern

Question

I am quite new to this code-first pattern. I have created a class and now I want to create a table in my database. in the PM console i wrote 'add migration addSummaries' and hit enter. and i have the following error:

PM> add-migration addsummaries
System.ArgumentNullException: Value cannot be null.
Parameter name: key
at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
at System.Data.Entity.ModelConfiguration.Configuration.Mapping.SortedEntityTypeIndex.Add(EdmEn    titySet entitySet, EdmEntityType entityType)
at  System.Data.Entity.ModelConfiguration.Configuration.Mapping.EntityMappingService.Analyze()
at  System.Data.Entity.ModelConfiguration.Configuration.ModelConfiguration.ConfigureEntityTypes (DbDatabaseMapping databaseMapping, DbProviderManifest providerManifest)
at     System.Data.Entity.ModelConfiguration.Configuration.ModelConfiguration.Configure(DbDatabase Mapping databaseMapping, DbProviderManifest providerManifest)
at System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest,  DbProviderInfo providerInfo)
at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext  internalContext)
at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
at System.Data.Entity.Internal.LazyInternalContext.get_CodeFirstModel()
at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter  writer)
at System.Data.Entity.Migrations.Extensions.DbContextExtensions.<>c__DisplayClass1. <GetModel>b__0(XmlWriter w)
at System.Data.Entity.Migrations.Extensions.DbContextExtensions.GetModel(Action`1 writeXml)
at System.Data.Entity.Migrations.Extensions.DbContextExtensions.GetModel(DbContext context)
at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration  configuration, DbContext usersContext)
at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration  configuration)
at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.GetMigrator()
at     System.Data.Entity.Migrations.Design.ToolingFacade.GetPendingMigrationsRunner.RunCore()
at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
Value cannot be null.
Parameter name: key
PM>

i have no clue what does it mean..can anybody help me to find the actual error??

EDIT:

 public class Summary
{
    [Key]
    public int Id { get; set; }

    public Guid SummaryId { get; set; }

    [Required]
    [Display(Name="Title")]
    [MaxLength(500)]
    public string SummaryTitle { get; set; }

    [Display(Name = "Description")]
    public string Description { get; set; }

    public DateTime PublishDate { get; set; }

    public virtual UserProfile Writer { get; set; }

    public bool PublishStatus { get; set; }

    [Required]
    public DateTime LastActionDate { get; set; }

    public HttpPostedFileBase DocumentFile { get; set; }
    public string FileName { get; set; }
    public string FileLocation { get; set; }

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

    public virtual ICollection<Course> Category { get; set; }
}

Can you please post the code for that class? Have you tried using the DbContext instead of the console? — Corey Adler
– Corey Adler, Commented Dec 11, 2012 at 21:37
You need to give more information that that. What does you entity POCO look like? — khellang
– khellang, Commented Dec 11, 2012 at 21:37
@IronMan84 I am not sure how to create table using DbContext..can u tell me plz? — Reza.Hoque
– Reza.Hoque, Commented Dec 11, 2012 at 21:44
Here's a tutorial: msdn.microsoft.com/en-us/data/gg192989.aspx — Corey Adler
– Corey Adler, Commented Dec 11, 2012 at 21:49

Andymore · Accepted Answer · 2013-08-02 01:23:07Z

2

If you have a class inherited from the "Summary" class, and it references anthor custom class that is not contained in your DbContext, you will encounter this issue.

answered Aug 2, 2013 at 1:23

Andymore

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