CourseFilter.cs

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using HwProj.CoursesService.API.Services;
using HwProj.Repositories.Net8;
using Newtonsoft.Json;

namespace HwProj.CoursesService.API.Models
{
    public class CourseFilter : IEntity<long>
    {
        [Key]
        public long Id { get; set; }
        
        /// <summary>
        /// This field is needed to save the filter in the database in Json format.
        /// </summary>
        /// <exception cref="InvalidOperationException">
        /// There are problems when deserializing data from the database.</exception>
        public string FilterJson
        {
            get => JsonConvert.SerializeObject(Filter, CourseFilterJsonSettings.Settings);
            set
            {
                Filter = JsonConvert.DeserializeObject<Filter>(value, CourseFilterJsonSettings.Settings) 
                         ?? throw new InvalidOperationException("The course filter cannot be deserialized.");
                Filter.FillEmptyFields();
            }
        }
        
        [NotMapped]
        public Filter Filter { get; set; }
    }
}