I wrote an webapi for an angular frontend web site with node express and postgresql 2 years ago we had a habbit from that project with frontend programmers and my web api. I give some fields on database that I never involved the frontenders use that field to save their kind of settings on that field. I’m using dapper becouse I love to have SQL in my hands instead of EFCore..

Now we are writing a new project with Asp.net.core 8 web api with angular but I have problems with json fields.

Lets set a sample

Database

create table users (
   user_id bigserial,
   username character varying[50],
   fullname character varying[200],
   password character varying[300],
   salt character varying[300],
   frontends_field jsonb,
   adress_data jsonb
)

public class User
{
    [Required]
    public long? User_Id { get; set; }
    
    [Required]
    [MaxLength(50)]
    public string UserName { get; set; } = string.Empty;
    
    [Required]
    [MaxLength(200)]
    public string FullName { get; set; } = string.Empty;

    [Required]
    [MaxLength(300)]
    public string Password { get; set; } = string.Empty;

    
    [MaxLength(300)]
    public string Salt { get; set; } = string.Empty;

    public ??WHICH_TYPE?? frontends_field { get; set; }
  
    public ??WHICH_TYPE?? adress_data { get; set; }

}

public class Adress_Data 
{
  public string? adress_name { get; set; }
  public string? streetinfo { get; set; }
  public string? buildinginfo { get; set; }
  public string? city { get; set; }

}

in a controller I save this data like this

[HttpPost]
public async Task<ActionResult<User>> PostUser([FromBody] User req)
{
    try
    {

        using var MyCnt = _db.GetConnection(); //Npgsqlconnection here
        {
            string MySql = """
     INSERT INTO public.users(username,fullname,password,salt,frontends_field,adress_data)
                VALUES (@username, @fullname,@password,@salt,@frontends_field,@adress_data)
                returning *;
                """;
            var result = await MyCnt.QueryFirstOrDefaultAsync<User>(MySql,req);

            return Ok(result);
        }
    }
    catch (Exception ex)
    {
        return BadRequest(ex);
    }
   
}

Sample JSON for req
{  "username" : "johndoe",
   "fullname" : "John DOE",
   "password" : "Please_123",
   "salt" "asdşfmi<sdmfpwefkpüpowefi",
   "frontends_field" : 
             { "somenumfield" : 15,
               "sometextfield" : "Cry me a river"
             },
   "adress_data" : 
   {
      "adress_name"  : "home",
      "streetinfo"   : "Susame Streeet No:21",
      "buildinginfo" : "A Block",
      "city" : "IZMIR"
   }
}

I really stuck at json side of the code…
Thanks All