How to upload file and array type data from angular to .net web api

this is the form group with nested array

this.InvoiceForm=this.fb.group({
      InvoiceNumber:[''],
      InvoicePath:[''],
      Discription:[''],
      EntryDate:[''],
      InvoiceItem:this.fb.array([this.AddItemFormGroup()]) 

this method add form Group dynamically.

AddItemFormGroup()
{
  return this.fb.group({
    ItemName:[''],
    ItemType:[''],
    Quantity:[''],
    Unit:[''],
    Category:[],
    Depo:[],
    Comments:['']
  })
}

the save method will call after submit method and I can access the form file but how I can access the nested from array which is InvoiceFrom in .net core web api.

  Save()
    {
    
      const formData=new FormData();
      formData.append('file',this.selectedFile,this.selectedFile.name);
      formData.append('Discription',this.InvoiceForm.get('Discription').value)
      formData.append('Date',this.InvoiceForm.get('EntryDate').value);
    
      formData.append('Items',this.InvoiceForm.get('InvoiceItem').value);
    
    this._http.post(environment.Item,formData,{
      headers:new HttpHeaders(
        {
          
          'enctype':'multipart/form-data'
        }
      )
    });
    }

Server side code

[HttpPost,DisableRequestSizeLimit] 
public async Task<ActionResult> AddItem() 
{ 
var file = Request.Form.Files[0]; 
var description = Request.Form["Discription"]; 
var date = Request.Form["date"]; 
var items = Request.Form["items"]; 
return Ok(); 
}