I’ve 3 classes.

• Header
• Property
• Units

Header class has one to many relation with Property Class & Property class has one to many relation with Units class.

Header DTO:

    public class HeaderDTO
    {
        public string Phone { get; set; } = null!;

        public string? Source { get; set; }

        public string? Address { get; set; }

        public string? Country { get; set; }

        public string? ShipTo { get; set; }

        public virtual ICollection<PropertyDTO> Properties { get; set; } = new List<PropertyDTO>();
    }

Property DTO:

public class PropertyDTO
{
    public string? Floor { get; set; }

    public string? Area { get; set; }

    public int Window { get; set; }

    public string Products { get; set; } = null!;

    public string? Login { get; set; }

    public string? ShipTo { get; set; }

    public int? Flag { get; set; }

    public virtual ICollection<UnitDTO> Units { get; set; } = new List<UnitDTO>();
}

Units DTO:

    public class UnitDTO
    {
        public string? UniqueName { get; set; }

        public int Height { get; set; }

        public int Width { get; set; }

        public int Panel { get; set; }

        public int? Belah { get; set; }

        public string? Img1 { get; set; }

        public string? Img2 { get; set; }

        public string? Img3 { get; set; }

        public List<TDataProduct>? products;
    }

I need to post multiple JSON records of Property & Units.
How can I iterate to units class.
I’ve tried to Call Include function but It’s not valid in this context.

Any guidance to solve this problem will be very much appreciated. 🙂

[HttpPost("SOPPOST")]
public async Task<ActionResult<TDataHeader>> CreateHeaders(HeaderDTO hdto)
{
    var header = new HeaderDTO
    {
        Address = hdto.Address,
        Country = hdto.Country,
        Phone = hdto.Phone,
        ShipTo = hdto.ShipTo,
        Source = hdto.Source
    };
    var phoneVerify = _context.TDataHeaders.Count(x => x.Phone == header.Phone);
    var headerImport = new TDataHeader
    {
        Address = header.Address,
        Country = header.Country,
        Phone = header.Phone,
        ShipTo = header.ShipTo,
        Source = header.Source
    };
    //if (phoneVerify == 0)
    //{
    //    await _context.TDataHeaders.AddAsync(headerImport);
    //}
    foreach (var prop in hdto.Properties)
    {
        var property = new TDataProperty
        {
            Floor = prop.Floor,
            Area = prop.Area,
            Windows = prop.Windows,
            Flag = prop.Flag,
            Login = prop.Login,
            Products = prop.Products,
            ShipTo = prop.ShipTo,
            Header = headerImport
        };
        foreach (var unit in prop.Units)
        {
            var unitModel = new TDataUnit
            {
                Belah = unit.Belah,
                Height = unit.Height,
                Width = unit.Width,
                Panel = unit.Panel,
                Img1 = unit.Img1,
                Img2 = unit.Img2,
                Img3 = unit.Img3,
                UniqueName = prop.Floor + "-" + prop.Area + "-" + prop.Windows,
                Property = property
            };
            await _context.TDataUnits.AddRangeAsync(unitModel);
        }
        await _context.TDataProperties.AddRangeAsync(property);
    }

    await _context.SaveChangesAsync();
    return Ok("Posted");
}

Above is working fine but need the Lambda Expression for the same.