Add models for basic to-do list management

AdvancedTodoList.Core/Models/TodoLists/TodoItem.cs

@@ -0,0 +1,73 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace AdvancedTodoList.Core.Models.TodoLists;
+
+/// <summary>
+/// Represents a to-do list item entity.
+/// </summary>
+public class TodoItem
+{
+    /// <summary>
+    /// An unique identifier for the to-do list item.
+    /// </summary>
+    [Key]
+    public int Id { get; set; }
+    /// <summary>
+    /// Name (title) of the to-do item.
+    /// </summary>
+    [MaxLength(NameMaxLength)]
+    public string Name { get; set; } = null!;
+    /// <summary>
+    /// Description of the to-do item.
+    /// </summary>
+    [MaxLength(DescriptionMaxLength)]
+    public string Description { get; set; } = null!;
+    /// <summary>
+    /// Current state of the to-do item.
+    /// </summary>
+    public TodoItemState State { get; set; }
+	/// <summary>
+	/// Deadline date for the todo item. Can be null.
+	/// </summary>
+	public DateTime? DeadlineDate { get; set; }
+
+	/// <summary>
+	/// Foreign key referencing the associated to-do list.
+	/// </summary>
+	[ForeignKey(nameof(TodoList))]
+	public string TodoListId { get; set; } = null!;
+
+	/// <summary>
+	/// Maximum allowed length of <see cref="Name"/>.
+	/// </summary>
+	public const int NameMaxLength = 100;
+    /// <summary>
+    /// Maximum allowed length of <see cref="Description"/>.
+    /// </summary>
+    public const int DescriptionMaxLength = 10_000;
+
+    /// <summary>
+    /// To-do list associated with this to-do item.
+    /// </summary>
+    public TodoList TodoList { get; set; } = null!;
+}
+
+/// <summary>
+/// An enum that represents the possible states of a to-do list item.
+/// </summary>
+public enum TodoItemState : byte
+{
+	/// <summary>
+	/// The task is active (default state).
+	/// </summary>
+	Active = 0,
+	/// <summary>
+	/// The task has been completed.
+	/// </summary>
+	Completed,
+	/// <summary>
+	/// The task has been skipped.
+	/// </summary>
+	Skipped
+}

AdvancedTodoList.Core/Models/TodoLists/TodoList.cs

@@ -0,0 +1,42 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace AdvancedTodoList.Core.Models.TodoLists;
+
+/// <summary>
+/// Represents a to-do list entity.
+/// </summary>
+public class TodoList
+{
+    /// <summary>
+    /// An unique identifier for the to-do list.
+    /// </summary>
+    [Key]
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    public string Id { get; set; } = null!;
+
+    /// <summary>
+    /// Name (title) of the to-do list.
+    /// </summary>
+    [MaxLength(NameMaxLength)]
+    public string Name { get; set; } = null!;
+	/// <summary>
+	/// Description of the to-do list.
+	/// </summary>
+	[MaxLength(DescriptionMaxLength)]
+	public string Description { get; set; } = null!;
+
+	/// <summary>
+	/// Maximum allowed length of <see cref="Name"/>.
+	/// </summary>
+	public const int NameMaxLength = 100;
+	/// <summary>
+	/// Maximum allowed length of <see cref="Description"/>.
+	/// </summary>
+	public const int DescriptionMaxLength = 25_000;
+
+	/// <summary>
+	/// Collection of to-do items associated with this todo list.
+	/// </summary>
+	public virtual IEnumerable<TodoItem> TodoItems { get; set; } = null!;
+}

AdvancedTodoList.Core/Services/ITodoListsService.cs

@@ -1,5 +1,5 @@
 using AdvancedTodoList.Core.Dtos;
-using AdvancedTodoList.Core.Models;
+using AdvancedTodoList.Core.Models.TodoLists;
 
 namespace AdvancedTodoList.Core.Services;
 

AdvancedTodoList.Infrastructure/Data/ApplicationDbContext.cs

@@ -1,6 +1,8 @@
 using AdvancedTodoList.Core.Models;
+using AdvancedTodoList.Core.Models.TodoLists;
 using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore;
+
 namespace AdvancedTodoList.Infrastructure.Data;
 
 public class ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) :