Seed Data in Entity Framework Core With Bogus

June 12, 2025 by Anuraj

dotnet efcore

In this blog post, we’ll learn how to Seed data in Entity Framework Core with Bogus. Bogus is a simple fake data generator for .NET languages like C#, F# and VB.NET. Bogus is fundamentally a C# port of faker.js and inspired by FluentValidation’s syntax sugar.

First we need to add nuget package - Bogus to the dotnet application. We can use the command - dotnet add package Bogus. For this demo I am fake data for User and Address class.

Here is the code snippet for User and Address class.

public class User
{
    public int Id { get; set; }
    public string? Name { get; set; }
    public string? Email { get; set; }
    public Address? Address { get; set; }
    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
    public DateTime? UpdatedAt { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public string? Street { get; set; }
    public string? City { get; set; }
    public string? State { get; set; }
    public string? ZipCode { get; set; }
}

Next we can use Faker<T> class. We can do like this.

var fakeAddress = new Faker<Address>()
    .RuleFor(a => a.Street, f => f.Address.StreetName())
    .RuleFor(a => a.City, f => f.Address.City())
    .RuleFor(a => a.State, f => f.Address.State())
    .RuleFor(a => a.ZipCode, f => f.Address.ZipCode());

var fakeUser = new Faker<User>()
    .RuleFor(u => u.Id, f => f.IndexFaker + 1)
    .RuleFor(u => u.Name, f => f.Name.FullName())
    .RuleFor(u => u.Email, f => f.Internet.Email())
    .RuleFor(u => u.Address, f => fakeAddress.Generate())
    .RuleFor(u => u.CreatedAt, f => f.Date.Past(1))
    .RuleFor(u => u.UpdatedAt, (f, u) => f.Date.Between(u.CreatedAt, DateTime.UtcNow));

var users = fakeUser.Generate(100);

In the above code snippet - we are creating fakeAddress instance. We can set values for different properties. And next we are creating fakeUser address. Similar to the fakeAddress instance, we are setting the fakeUser property values. And this expression - var users = fakeUser.Generate(100); will generate 100 records. To see the data to the database we can use override or modify the onModelCreating() method in the DbContext class like this.

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    var fakeAddress = new Faker<Address>()
        .RuleFor(a => a.Street, f => f.Address.StreetName())
        .RuleFor(a => a.City, f => f.Address.City())
        .RuleFor(a => a.State, f => f.Address.State())
        .RuleFor(a => a.ZipCode, f => f.Address.ZipCode());

    var fakeUser = new Faker<User>()
        .RuleFor(u => u.Id, f => f.IndexFaker + 1)
        .RuleFor(u => u.Name, f => f.Name.FullName())
        .RuleFor(u => u.Email, f => f.Internet.Email())
        .RuleFor(u => u.Address, f => fakeAddress.Generate())
        .RuleFor(u => u.CreatedAt, f => f.Date.Past(1))
        .RuleFor(u => u.UpdatedAt, (f, u) => f.Date.Between(u.CreatedAt, DateTime.UtcNow));

    var users = fakeUser.Generate(100);
    modelBuilder.Entity<User>().HasData(users);
}

This way we can create test data for your applications. We can use the WebHostEnvironment.IsDevelopment() condition check to seed the data in the database in Development environment only.

Happy Programming

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