C#•2w ago

Problem while "dotnet ef migrations add Init"

When I'm trying to add data base migration i get error "The seed entity for entity type 'Contract' cannot be added because a non-zero value is required for property 'ContractId'. Consider providing a negative value to avoid collisions with non-seed data." table (look screenshot) insert :

   new Contract
            {
                CustomerId = 1, SoftwareId = 1, Version = "1.0", StartDate = new DateTime(2024, 1, 1),
                EndDate = new DateTime(2024, 1, 10), Price = 1000.00m, DiscountId = 1, SupportYears = 1,
                IsSigned = false
            },

   new Contract
            {
                CustomerId = 1, SoftwareId = 1, Version = "1.0", StartDate = new DateTime(2024, 1, 1),
                EndDate = new DateTime(2024, 1, 10), Price = 1000.00m, DiscountId = 1, SupportYears = 1,
                IsSigned = false
            },

table has autoincrementation:

modelBuilder.Entity<Contract>()
            .Property(c => c.ContractId)
            .ValueGeneratedOnAdd();

modelBuilder.Entity<Contract>()
            .Property(c => c.ContractId)
            .ValueGeneratedOnAdd();

table code:

using System.ComponentModel.DataAnnotations.Schema;

namespace Company_APBD.Models;

public class Contract
{
    public int ContractId { get; set; }
    public int CustomerId { get; set; }
    public int SoftwareId { get; set; }
    public string Version { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
    public decimal Price { get; set; }
    public int DiscountId { get; set; }
    public int SupportYears { get; set; }
    public bool IsSigned { get; set; }

   
}

using System.ComponentModel.DataAnnotations.Schema;

namespace Company_APBD.Models;

public class Contract
{
    public int ContractId { get; set; }
    public int CustomerId { get; set; }
    public int SoftwareId { get; set; }
    public string Version { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
    public decimal Price { get; set; }
    public int DiscountId { get; set; }
    public int SupportYears { get; set; }
    public bool IsSigned { get; set; }

   
}

32 Replies

Salman•2w ago

You don't need this code :

c#
modelBuilder.Entity<Contract>()
            .Property(c => c.ContractId)
            .ValueGeneratedOnAdd();

c#
modelBuilder.Entity<Contract>()
            .Property(c => c.ContractId)
            .ValueGeneratedOnAdd();

EfCore knows that ContractId is the PK of your table so you don't need to specify it manually. Remove it , delete the previous migrations and then add a fresh migration

Juks•2w ago

still same problem my migration doesn't even create so i cant delete anything

Salman•2w ago

can you show the entire db context class and the full error you get while migration ?

Juks•2w ago

sure wait let me add it to github

Salman•2w ago

sure

Juks•2w ago

https://github.com/Juks0/CompanyAPI/tree/master

GitHub

GitHub - Juks0/CompanyAPI at master

Contribute to Juks0/CompanyAPI development by creating an account on GitHub.

Salman•2w ago

this code is also redundant :

c#
 modelBuilder.Entity<Customer>().HasKey(c => c.CustomerId);
        modelBuilder.Entity<Discount>().HasKey(s => s.DiscountId);
        modelBuilder.Entity<Contract>().HasKey(c => c.ContractId);
        modelBuilder.Entity<Employee>().HasKey(e => e.EmployeeId);
        modelBuilder.Entity<Subscription>().HasKey(s => s.SubscriptionId);

c#
 modelBuilder.Entity<Customer>().HasKey(c => c.CustomerId);
        modelBuilder.Entity<Discount>().HasKey(s => s.DiscountId);
        modelBuilder.Entity<Contract>().HasKey(c => c.ContractId);
        modelBuilder.Entity<Employee>().HasKey(e => e.EmployeeId);
        modelBuilder.Entity<Subscription>().HasKey(s => s.SubscriptionId);

Juks•2w ago

deleted it, still the same

Salman•2w ago

c#
 new Customer
            {
                CustomerId = 6, CustomerType = "Company", Address = "303 Birch St, Warsaw, Poland",
                Email = "info@company1.com", PhoneNumber = "+48678901234"
            },

c#
 new Customer
            {
                CustomerId = 6, CustomerType = "Company", Address = "303 Birch St, Warsaw, Poland",
                Email = "info@company1.com", PhoneNumber = "+48678901234"
            },

why manually passing the CustomerId ?

Juks•2w ago

oh there are 2 customer insterts my bad

Salman•2w ago

clean up your DB Context class...and see if it works. Overall code seems fine to me other than manually specifying the PK etc

Juks•2w ago

i made Insert for companyCustomer, i get diffrent error withnot specyfying pk exactly i need to specify primary ket at the top of class in Models? and every goreign key like here?

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;

namespace APBD_kol2.Models;


[Table("backpacks")]
[PrimaryKey(nameof(CharacterId), nameof(ItemId))]
public class Backpacks
{
    public int CharacterId { get; set; }
    public int ItemId { get; set; }
    public int Amount { get; set; }
    
    [ForeignKey(nameof(CharacterId))]
    public Characters Characters { get; set; }
    [ForeignKey(nameof(ItemId))]
    public Items Items { get; set; }

}

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;

namespace APBD_kol2.Models;


[Table("backpacks")]
[PrimaryKey(nameof(CharacterId), nameof(ItemId))]
public class Backpacks
{
    public int CharacterId { get; set; }
    public int ItemId { get; set; }
    public int Amount { get; set; }
    
    [ForeignKey(nameof(CharacterId))]
    public Characters Characters { get; set; }
    [ForeignKey(nameof(ItemId))]
    public Items Items { get; set; }

}

Salman•2w ago

does the migration work when you manually add the PK while seeding the data ?

Juks•2w ago

wym manually

Salman•2w ago

no you don't need that

Juks•2w ago

so how should i do it then?

Salman•2w ago

I mean when you include the PK in the object while seeding

Juks•2w ago

let me check

Salman•2w ago

sure, include the PK in the objects and then see

Juks•2w ago

yh it did work so if i dont provide anything just leave this blind it will know it need to autoincrement ID? no it wont when i didnt provide pk manually i get the same error The seed entity for entity type 'Customer' cannot be added because a non-zero value is required for property 'CustomerId'. Consider providing a negative value to avoid collisions with non-seed data.

Salman•2w ago

You need to provide the PK while seeding but not in the application while inserting You will see when you Will add a new record using EF Core without providing PK , it'll work

Juks•2w ago

seeding means where?

Salman•2w ago

In Db Context

Juks•2w ago

yeah i know that, but could you provide me an example, i have no idea where to specify a PK

Salman•2w ago

well listen. let's say your model is called Book , it'll look like this :

c#
public class Book {
public int Id {get; set;} //BookId can also be used but Id is more concise
public string name {get; set;}

c#
public class Book {
public int Id {get; set;} //BookId can also be used but Id is more concise
public string name {get; set;}

So the Id here is the PK and EFCore knows it . So while seeding the data you need to provide this PK which is Id in this case but in the application while adding something to the schema/database you don't need to specify this. For example you'd just do :

c#

var newBook = new Book { name = "My Book" };
await _myContext.Books.Add(newBook);
await SaveChangesAsync();

c#

var newBook = new Book { name = "My Book" };
await _myContext.Books.Add(newBook);
await SaveChangesAsync();

https://learn.microsoft.com/en-us/ef/core/modeling/keys

Juks•2w ago

Exactly, so i provided class:

public class Customer
{
    public int CustomerId { get; set; }

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

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

    [Required]
    [EmailAddress]
    public string Email { get; set; }

    [Required]
    [Phone]
    public string PhoneNumber { get; set; }
}

public class Customer
{
    public int CustomerId { get; set; }

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

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

    [Required]
    [EmailAddress]
    public string Email { get; set; }

    [Required]
    [Phone]
    public string PhoneNumber { get; set; }
}

my insert looks like this:

  modelBuilder.Entity<Customer>().HasData(new List<Customer>
        {
            new Customer
            {
                CustomerType = "Company", Address = "606 Aspen St, Wroclaw, Poland",
                Email = "sales@company4.com",
                PhoneNumber = "+48901234567"
            },
            new Customer
            {
                CustomerType = "Company", Address = "707 Willow St, Gdansk, Poland",
                Email = "info@company5.com",
                PhoneNumber = "+48101234568"
            }
        });

  modelBuilder.Entity<Customer>().HasData(new List<Customer>
        {
            new Customer
            {
                CustomerType = "Company", Address = "606 Aspen St, Wroclaw, Poland",
                Email = "sales@company4.com",
                PhoneNumber = "+48901234567"
            },
            new Customer
            {
                CustomerType = "Company", Address = "707 Willow St, Gdansk, Poland",
                Email = "info@company5.com",
                PhoneNumber = "+48101234568"
            }
        });

do i need to provide this part of code? I dont think thats the reason

await _myContext.Books.Add(newBook);
await SaveChangesAsync();

await _myContext.Books.Add(newBook);
await SaveChangesAsync();

In link you send there is a Example where we specify PK in model class

[PrimaryKey(nameof(State), nameof(LicensePlate))]
internal class Car
{
    public string State { get; set; }
    public string LicensePlate { get; set; }

    public string Make { get; set; }
    public string Model { get; set; }
}

[PrimaryKey(nameof(State), nameof(LicensePlate))]
internal class Car
{
    public string State { get; set; }
    public string LicensePlate { get; set; }

    public string Make { get; set; }
    public string Model { get; set; }
}

should'nt i do it like that? and btw thanks for your help you're legend

Salman•2w ago

Oh no! As I said while seeding you do need to provide the PK i.e

c#
  modelBuilder.Entity<Customer>().HasData(new List<Customer>
        {
            new Customer
            {
CustomerId = 1,
                CustomerType = "Company", Address = "606 Aspen St, Wroclaw, Poland",
                Email = "sales@company4.com",
                PhoneNumber = "+48901234567"
            },
           
        });

c#
  modelBuilder.Entity<Customer>().HasData(new List<Customer>
        {
            new Customer
            {
CustomerId = 1,
                CustomerType = "Company", Address = "606 Aspen St, Wroclaw, Poland",
                Email = "sales@company4.com",
                PhoneNumber = "+48901234567"
            },
           
        });

Juks•2w ago

yh, but how to do it when i dont wan't to provide it

Salman•2w ago

c#
await _myContext.Books.Add(newBook);
await SaveChangesAsync();

c#
await _myContext.Books.Add(newBook);
await SaveChangesAsync();

this part is for the EfCore queries not for the seeding data and is not relevant in the db context class. You'll use EfCore throughout your application . You'd need to provide it while seeding

Juks•2w ago

so to make it clear as i understand it

  modelBuilder.Entity<Customer>().HasData(new List<Customer>
        {
            new Customer
            {
CustomerId = 1,
                CustomerType = "Company", Address = "606 Aspen St, Wroclaw, Poland",
                Email = "sales@company4.com",
                PhoneNumber = "+48901234567"
            },
           
        });

  modelBuilder.Entity<Customer>().HasData(new List<Customer>
        {
            new Customer
            {
CustomerId = 1,
                CustomerType = "Company", Address = "606 Aspen St, Wroclaw, Poland",
                Email = "sales@company4.com",
                PhoneNumber = "+48901234567"
            },
           
        });

this is only way to do it because i always need to provide customer ID while seeding, you can't use auto incrementation here?

Salman•2w ago

yes while seeding you'd need to provide it

Juks•2w ago

thanks, ill try to make it now got it thanks a lot my man

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Problem while "dotnet ef migrations add Init"