C#•7mo ago

✅ EF Core navigational properties

This works fine (no navigational property to Business):

class Business
- ...
- Address Address { get; set; }

class Address
- ...

class Business
- ...
- Address Address { get; set; }

class Address
- ...

This causes an error:

class Business
- ...
- Address Address { get; set; }

class Address
- ...
- Business { get; set; }

class Business
- ...
- Address Address { get; set; }

class Address
- ...
- Business { get; set; }

InvalidOperationException: The value of 'Address.Id' is unknown when attempting to save changes. This is because the property is also part of a foreign key for which the principal entity in the relationship is not known

InvalidOperationException: The value of 'Address.Id' is unknown when attempting to save changes. This is because the property is also part of a foreign key for which the principal entity in the relationship is not known

Initialization code:

            var address = new Address
            {
                Street = "SName",
                City = "CName",
            };

            await dbContext.Addresses.AddAsync(address);

            var address = new Address
            {
                Street = "SName",
                City = "CName",
            };

            await dbContext.Addresses.AddAsync(address);

How can I make this work while also keeping Address' nav property to Business? Please @ me so I respond immediately

27 Replies

Angius•7mo ago

I assume

- Business { get; set; }

- Business { get; set; }

is supposed to be

- Business Business { get; set; }

- Business Business { get; set; }

? Also, don't use .AddAsync(), it's not an inherently asynchronous operation.

Lounder•7mo ago

I just solved the problem Old code:

           builder.Entity<Business>()
               .HasOne(b => b.Address)
               .WithOne(a => a.Business)
               .HasForeignKey<Address>(a => a.Id);

           builder.Entity<Business>()
               .HasOne(b => b.Address)
               .WithOne(a => a.Business)
               .HasForeignKey<Address>(a => a.Id);

New code:

            builder.Entity<Address>()
                .HasOne(b => b.Business)
                .WithOne(a => a.Address)
                .HasForeignKey<Business>(a => a.Id);

            builder.Entity<Address>()
                .HasOne(b => b.Business)
                .WithOne(a => a.Address)
                .HasForeignKey<Business>(a => a.Id);

I initialize Address first so I suppose it must be the "primary" entity or however it is called.

Jimmacle•7mo ago

you shouldn't have to do either of those, that relationship should be discovered by convention

Lounder•7mo ago

I do this so I could get the business entity from the address entity: Address.Business.Id for example

Jimmacle•7mo ago

that's fine, i'm staying this is a basic relationship that you do not need to configure yourself

Lounder•7mo ago

In this case it isn't very useful but I imagine that in the other entities I will need this and I guess it's better to have it the same everywhere

Jimmacle•7mo ago

EF should automatically set it up

Lounder•7mo ago

Are you talking about fluent api

Jimmacle•7mo ago

yes

Lounder•7mo ago

I get an error without it Something along the lines of "can't determine parent" Aka what points to what

Jimmacle•7mo ago

weird i'd personally make the address an owned entity

Lounder•7mo ago

Maybe I'm just doing something wrong Can you define owned entity First time hearing it

Jimmacle•7mo ago

it will be stored in-line in the business table

Lounder•7mo ago

Oh so no mention in dbcontect as dbset?

Jimmacle•7mo ago

so your business table gets columns like Address_Street, Address_City, etc right to me an address isn't an entity, it's just a value so it doesn't make sense to treat it like an independent thing

Lounder•7mo ago

Isn't this applicable to every one to one relationship

Jimmacle•7mo ago

theoretically but think of it this way a business has an address, but does it necessarily make sense for an address to have a business or no business at all? (it might, depends on your requirements)

Lounder•7mo ago

I think an address should have a business because you could search up the street name or the city And the business/es would pop up as results

Jimmacle•7mo ago

you can do that whether it's owned or not, it just changes the table the data lives in

Lounder•7mo ago

Oh or maybe you mean that We never get the address as a separate entity, it is always interlocked with business So it makes it useless to be seperate when you always call the business entity

Jimmacle•7mo ago

right

Lounder•7mo ago

Gotcha I agree

Jimmacle•7mo ago

so it sounds like there's no reason for an address to be able to exist in the database all by itself

Lounder•7mo ago

Right Okay I will work on that, thank you I will close this thread now, good night 👋

Jimmacle•7mo ago

iirc EFC 8 has better support for complex types without making them owned, could look into that too

Lounder•7mo ago

I'm limited to net 6

Jimmacle•7mo ago

ah, owned it is then

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✅ EF Core navigational properties