C#•9mo ago

✅ How to create migration correctly? What do I do wrong?

Command in Package Manager Console: PM> add-migration UpdateSomeModels -contex ReadModelDbContext Error:

Unable to create a 'DbContext' of type 'ReadModelDbContext'. The exception 'Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[ReadModel.Infrastructure.ReadModelDbContext]' while attempting to activate 'ReadModel.Infrastructure.ReadModelDbContext'.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Unable to create a 'DbContext' of type 'ReadModelDbContext'. The exception 'Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContextOptions`1[ReadModel.Infrastructure.ReadModelDbContext]' while attempting to activate 'ReadModel.Infrastructure.ReadModelDbContext'.' was thrown while attempting to create an instance. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

public sealed class ReadModelDbContext: DbContext
{
    public ReadModelDbContext(DbContextOptions<ReadModelDbContext> options)
        : base(options)
    {
    }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Qualification>().HasAlternateKey(x => x.Identity);
        modelBuilder.Entity<Function>().HasIndex(x => x.Name);
        modelBuilder.Entity<Resource>().HasIndex(x => x.Identity);
        modelBuilder.Entity<Node>().HasIndex(x => x.Identity);
        modelBuilder.Entity<Location>().HasIndex(x => x.Identity);
        modelBuilder.Entity<Shift>().HasAlternateKey(x => new { x.ScheduledStart, x.Type, x.ResourceId });
    }

    public DbSet<Qualification> Qualifications => Set<Qualification>();
    public DbSet<Function> Functions => Set<Function>();
    public DbSet<FunctionQualification> FunctionQualifications => Set<FunctionQualification>();
    public DbSet<ResourceQualification> ResourceQualifications => Set<ResourceQualification>();
    public DbSet<Resource> Resources => Set<Resource>();
    public DbSet<Node> Nodes => Set<Node>();
    public DbSet<Location> Locations => Set<Location>();
    public DbSet<Edge> Edges => Set<Edge>();
    public DbSet<ShiftQualification> ShiftQualifications => Set<ShiftQualification>();
    public DbSet<Shift> Shifts => Set<Shift>();
}

public sealed class ReadModelDbContext: DbContext
{
    public ReadModelDbContext(DbContextOptions<ReadModelDbContext> options)
        : base(options)
    {
    }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Qualification>().HasAlternateKey(x => x.Identity);
        modelBuilder.Entity<Function>().HasIndex(x => x.Name);
        modelBuilder.Entity<Resource>().HasIndex(x => x.Identity);
        modelBuilder.Entity<Node>().HasIndex(x => x.Identity);
        modelBuilder.Entity<Location>().HasIndex(x => x.Identity);
        modelBuilder.Entity<Shift>().HasAlternateKey(x => new { x.ScheduledStart, x.Type, x.ResourceId });
    }

    public DbSet<Qualification> Qualifications => Set<Qualification>();
    public DbSet<Function> Functions => Set<Function>();
    public DbSet<FunctionQualification> FunctionQualifications => Set<FunctionQualification>();
    public DbSet<ResourceQualification> ResourceQualifications => Set<ResourceQualification>();
    public DbSet<Resource> Resources => Set<Resource>();
    public DbSet<Node> Nodes => Set<Node>();
    public DbSet<Location> Locations => Set<Location>();
    public DbSet<Edge> Edges => Set<Edge>();
    public DbSet<ShiftQualification> ShiftQualifications => Set<ShiftQualification>();
    public DbSet<Shift> Shifts => Set<Shift>();
}

7 Replies

Pobiega•9mo ago

Do you have di setup for this as well?

Tvde1•9mo ago

you might need to add which project has your DB context and which has your startup

Pobiega•9mo ago

The migration builder will actually build your app configuration and service provider

Angius•9mo ago

Seems like the config isn't hooked up properly

SWEETPONY•9mo ago

I have two projects: A with DI setup B with dbcontext I want to create migrations in B that's why I set B as startup project and write this command: add-migration UpdateSomeModels -contex dbcontex but it doesn't work

Tvde1•9mo ago

you need to do

add-migration MyNewThings -p MyProject.Data/ -s MyProject.API

add-migration MyNewThings -p MyProject.Data/ -s MyProject.API


the context option shouldn't be used unless you have multiple DB contexts
also I recommend to use the newer tool:

dotnet ef migrations add ...`

SWEETPONY•9mo ago

ahh I found the problem! we should set a class with DI as startup and create migration in project with dbcontext thanks

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✅ How to create migration correctly? What do I do wrong?