Entity Framework, adding table to existing context

Question

After following the steps for mapping an existing table to a model, I realized the table had some dependencies.

For the last three times that helped, I just droped the whole DBContext and started again.

I would like to just update my context for accommodate another table, which relates to the current ones.

My current context is:

public partial class CompanyContext : DbContext
{
    public CompanyContext() : base("name=CompanyContext")
    {
    }

    public virtual DbSet<company> companies { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<company>()
            .Property(e => e.name)
            .IsUnicode(false);

        modelBuilder.Entity<company>()
            .Property(e => e.symbol)
            .IsUnicode(false);

        modelBuilder.Entity<company>()
            .Property(e => e.address)
            .IsUnicode(false);

        modelBuilder.Entity<company>()
            .Property(e => e.zipcode)
            .IsFixedLength()
            .IsUnicode(false);

        modelBuilder.Entity<company>()
            .Property(e => e.cnpj)
            .IsFixedLength()
            .IsUnicode(false);
    }
}

A company's record has id_city which is not even appearing in the DbContext. But it is there in the model:

[Table("company")]
public partial class company
{
    public int id { get; set; }

    [Required]
    [StringLength(70)]
    public string name { get; set; }

    [StringLength(10)]
    public string symbol { get; set; }

    [StringLength(80)]
    public string address { get; set; }

    [StringLength(8)]
    public string zipcode { get; set; }

    public int id_city { get; set; }

    public int id_segment { get; set; }

    [StringLength(14)]
    public string cnpj { get; set; }

    [Column(TypeName = "date")]
    public DateTime? open_date { get; set; }
}

I would like to add the table cities to this context, what should I do? Is there any wizard for helping it?

I thought it could be just add something like:

public virtual DbSet<city> cities { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<city>()
        .Property(e => e.name)
        .IsUnicode(false);
}

but it doesn't work.

I am using version 5, does it matter? I mean, has this behavior changed accross versions? — Thiago Melo
– Thiago Melo, Commented Apr 17, 2017 at 19:14
No, there is no wizzard. There's a thing called EntityFramework Reverse POCO Generator, but what you did should be enough. What's the problem? "It doesn't work." isn't really informative. — Gert Arnold
– Gert Arnold, Commented Apr 17, 2017 at 19:22
I am sorry, I don't know exactly what happened. Before it was just passing by, without returning any records, now it is. I am sorry, don't know what has changed actually — Thiago Melo
– Thiago Melo, Commented Apr 17, 2017 at 19:31

vittore · Accepted Answer · 2017-04-17 18:55:38Z

2

Adding property like

public virtual DbSet<company> companies { get; set; }

To the context tells EF that you have a table that will hold records of type company. This one line is enough and table will use standard mapping so table name will be companies.

You need to do the same for cities.

public virtual DbSet<city> cities { get; set; }

You also need to add virtual property City to the company class if you want to have relationship in the database and remove id_city field. If you want id of related city to be exposed explicitly on the company class , you have to either use naming convention that EF follows, ie name it cityId or add fluent mapping for it.

answered Apr 17, 2017 at 18:55

vittore

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3 Comments

Thiago Melo Over a year ago

I am giving it a try again

Thiago Melo Over a year ago

Following your approach I got a proper error which helped me to figure out what was happening: The specified cast from a materialized 'System.Byte' type to the 'System.Int32' type is not valid. It was not blowing up before.

Thiago Melo Over a year ago

I mean, I thought I had made this before, but it was not returning any records, now I just made again, following your procedure, with lead to the same code (I guess) and it worked, sorry, don't know what I have done before

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