ASP.Net MVC Model Class key identifier

Question

I am new to ASP.Net MVC and I am trying to get a better understanding of ASP.Net MVC. I did a couple tutorials and made a few models in those tutorials. One question that kept popping up in my head was: When would I use public int Id { get; set; } and when would I be using public int MyClassNameId { get; set; } instead as identifier for my model class? Would it matter if I would use a custom property name instead of the default Id name for my identifier for a model class?

For example, why would I use public int ArtistId { get; set; } over public int Id { get; set; }?:

public class Artist
{
    public int ArtistId { get; set; }
    public string Name { get; set; }
}

Is it so that it matches a property name in another class in which it will be used as Foreign Key?

Samvel Petrosov · Accepted Answer · 2017-05-07 16:12:57Z

2

Entity Framework CodeFirst recognize the key, by default, by name. Valid names are Id or <YourClassName>Id.

Your property should be named Id or AccountTypesId

Another way is to use the ModelBuilder to specify the key.

Sample

public class MyDbContext : DbContext
{
    public DbSet<Artists> Artists{ get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Artists>.HasKey(x => x.ArtistId);
        base.OnModelCreating(modelBuilder);
    }
}

More about it you can find here

answered May 7, 2017 at 16:12

Samvel Petrosov

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6 Comments

Barrosy Over a year ago

Yes this I do understand. But my question was to understand why to use rather the first than the latter as identifier name for that property.

Samvel Petrosov Over a year ago

@Barrosy while creating the model Entity Framework's Core is looking for properties or fields with name Id or <YourClassName>Id that is just a convention.

Barrosy Over a year ago

I know but my question is why to use <YourClassName>Id instead of Id?

Samvel Petrosov Over a year ago

@Barrosy you can use any of them there is no difference

Samvel Petrosov Over a year ago

@Barrosy if you will use your primary key as foreign key you had better use <YourClassName>Id or modelBuilder in order not to get confusions with the primary keys with name Id from the second table.

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Anshul · Accepted Answer · 2017-05-07 16:12:56Z

0

If you use custom property names then compiler will not understand it's meaning that it is an id and must be used as primary key in database table. when you name it id compiler understands it's meaning .

answered May 7, 2017 at 16:12

Anshul

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Comments

Ali Prasla · Accepted Answer · 2017-05-07 16:19:25Z

This depends on whether or not using Entity Framework to set up your databases. If you are Entity Framework looks for specific property names to identity as Primary Keys.

For example, let's say you have a model called Book.

public class Book
{
 public string Title {get; set;}
 //all other properties here
}

When Entity Framework tries to set up your database, it looks for a property that it can identify as a primary key corresponding to the specific model. In this case EF would look for "BookID" as a primary key. So if you wished to have an accessible primary key property you would set it up like this.

public class Book
{
 public int BookID {get;set;}
 public string Title {get; set;}
 //all other properties here
}

If you wished to set up a primary key that was not called "BookID", you could use a data annotation:

public class Book
{
 [Key]
 public int BookIdentifier{get;set;}
 public string Title {get; set;}
 //all other properties here
}

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