C#•2y ago

❔ [EF Core] Ignore properties from constructor of base class

Hey, I am currently trying to implement a new model in EF Core which looks like this:

internal class PlayerV : Player
{
    public bool LoggedIn { get; set; }

    public PlayerV(ICore Core, IntPtr NativePointer, ushort Id) : base(Core, NativePointer, Id)
    {
        LoggedIn = false;
    }
}

internal class PlayerV : Player
{
    public bool LoggedIn { get; set; }

    public PlayerV(ICore Core, IntPtr NativePointer, ushort Id) : base(Core, NativePointer, Id)
    {
        LoggedIn = false;
    }
}

In the current implementation, I only want to save the LoggedIn property to the database, because I don't need the other ones from the base class. They're just needed for the business logic in the code. So I tried to ignore them with the ModelBuilder:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<PlayerV>()
        .Ignore(x => x.Core)
        .Ignore(x => x.NativePointer)
        .Ignore(x => x.Id);
}

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<PlayerV>()
        .Ignore(x => x.Core)
        .Ignore(x => x.NativePointer)
        .Ignore(x => x.Id);
}

But I am still getting the error message:

No suitable constructor was found for entity type 'PlayerV'. The following constructors had parameters that could not be bound to properties of the entity type:
    Cannot bind 'Core', 'NativePointer', 'Id' in 'PlayerV(ICore Core, IntPtr NativePointer, ushort Id)'
Note that only mapped properties can be bound to constructor parameters. Navigations to related entities, including references to owned types, cannot be bound.

No suitable constructor was found for entity type 'PlayerV'. The following constructors had parameters that could not be bound to properties of the entity type:
    Cannot bind 'Core', 'NativePointer', 'Id' in 'PlayerV(ICore Core, IntPtr NativePointer, ushort Id)'
Note that only mapped properties can be bound to constructor parameters. Navigations to related entities, including references to owned types, cannot be bound.

That kinda makes sense to me. But I really need to find a way how just to ignore the properties from the base class, I don't want an additional database wrapper class or something. Is that possible?

16 Replies

jcotton42•2y ago

the issue is the constructor how is EF supposed to construct your model when it doesn't have values for any of the parameters? the properties aren't the issue

Angius•2y ago

EF models should, ideally, not have a custom constructor

jcotton42•2y ago

though, having a model like that (nearly all the props ignored) is really smelly

Angius•2y ago

And instead of .Ignore()ing a bunch of properties... just make a model that doesn't have them Exactly

jcotton42•2y ago

your db models should be db models and nothing else also, even if what you currently had worked, that table has no primary key

𝐃𝐞𝐫𝐢𝐬𝐨𝐧OP•2y ago

okay, thanks for the tips guys. so the better approach would be to create an extra e.g. PlayerDB class, which can be constructed from PlayerV which just handles the database stuff?

jcotton42•2y ago

yes and it also needs a primary key some sort of unique ID

Angius•2y ago

Unless the Player class you inherit from has it

𝐃𝐞𝐫𝐢𝐬𝐨𝐧OP•2y ago

already prepared that for the PlayerDB awesome

Id = Guid.NewGuid().ToString();

Id = Guid.NewGuid().ToString();

sadly, the Player class isn't even meant to be a database model. i just hoped i could make it fit for me, you know

Angius•2y ago

Let the db generate the PK Far as what is made to be in the db and what isn't meant to... EF models model the database

jcotton42•2y ago

don't try to be clever with your db models it just ends in pain

Angius•2y ago

They should contain all that you need stored there And only what you need stored there .Select() into other classes if need be Or use an automapper Or something else

jcotton42•2y ago

ugh please no

Angius•2y ago

But EF models should just describe the database

𝐃𝐞𝐫𝐢𝐬𝐨𝐧OP•2y ago

okay i see, i'll keep that in mind. thank you guys so far

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ [EF Core] Ignore properties from constructor of base class