Define Entities

Learn how to define entity types using JD.Domain's fluent DSL.

Goal

Create an entity definition with properties that can be used for EF Core configuration and code generation.

Prerequisites

JD.Domain.Modeling package installed
Basic understanding of domain modeling

Steps

1. Create the Entity Class

Define a simple POCO class:

public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public string Email { get; set; } = string.Empty;
    public DateTime CreatedAt { get; set; }
}

2. Define the Entity in DSL

Use the fluent DSL to describe the entity:

using JD.Domain.Modeling;

var domain = Domain.Create("MyDomain")
    .Entity<Customer>(entity => entity
        .Property(c => c.Id)
        .Property(c => c.Name)
        .Property(c => c.Email)
        .Property(c => c.CreatedAt))
    .Build();

3. Add Multiple Entities

Define multiple entities in one domain:

var domain = Domain.Create("ECommerce")
    .Entity<Customer>(e => e
        .Property(c => c.Id)
        .Property(c => c.Name)
        .Property(c => c.Email))
    .Entity<Order>(e => e
        .Property(o => o.Id)
        .Property(o => o.CustomerId)
        .Property(o => o.TotalAmount))
    .Build();

Result

You now have a domain manifest describing your entities. This manifest can be used for:

Generating EF Core configurations
Creating business rules
Generating domain types
Creating snapshots

Next Steps

Define Value Objects - Add value object types
Configure Keys - Add primary keys
Create Invariants - Add business rules

Table of Contents