[JsonObject(IsReference = false)]

public class Demande
{

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }

[Display(Name = "Titre")]
public string? Titre { get; set; }

[Display(Name = "Description")]
public string? Description { get; set; }

[Required(ErrorMessage = "Le champ Date de création est requis.")]
[Display(Name = "Date de création")]
[DataType(DataType.DateTime)]
public DateTime DateCreation { get; set; }

[EnumDataType(typeof(Status))]
public Status Status { get; set; }

public string? UserI { get; set; }
public ApplicationUser? User { get; set; } 

}

[JsonObject(IsReference = false)]

public class User
{
    
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public string? UserId { get; set; }

    
    public string? Name { get; set; }

    
    [EmailAddress]
    [DataType(DataType.EmailAddress)]
    public string? Email { get; set; }

    [Required]
    [DataType(DataType.Password)]
    public string? Password { get; set; }

    
    [DataType(DataType.Password)]
    [Compare(nameof(Password))]
    public string? ConfirmPassword { get; set; }

   
    public Roles Role { get; set; }

    public ICollection<Demande>? Demandes { get; set; }
}

builder.Services.AddControllers().AddJsonOptions((options =>
{
options.JsonSerializerOptions.ReferenceHandler = System.Text.Json.Serialization.ReferenceHandler.IgnoreCycles;}))

Result :::

Response body
Download
{
“$id”: “1”,
“$values”: []
}