Passing a nested list of objects with objects in post ajax method for web api

I am stuck in situation where I have nested list of objects inside objects. I am stuck and can't move any further.

Working fine without passing oNestedClass.

And I'm having trouble passing a list of objects via JSON to Web Api.

The controller method:

[HttpPost("SaveDocuments")]
public IActionResult SaveDocuments(Documenttest saveDocs)
{
    var docTypeList = docContext.SaveDocuments(saveDocs);
    return Ok(docTypeList);
}

Class:

public class Documenttest
{
    public int Id { get; set; }
    public string? FirstName { get; set; }
    public string? LastName { get; set; }
    public string? Gender { get; set; }
    public List<NestedClass>? oNestedClass { get; set; } = new();
}

public class NestedClass
{
    public string? StdType { get; set; }
    public IFormFile? StdFile { get; set; }
}

Calling from .aspx page:

$("#postform").submit(function (e) {
var apiurl = "https://localhost:7168/api/NestClass/SaveDocuments?";
var fileUpload = $(".uplFile");

var stdDetails = [];

for (var i = 0; i < fileUpload.length; i++) {
	var files = fileUpload[i];
	
	if (files.files.length > 0) {
		debugger
		stdDetails.push({ "StdType ": i, "StdFile ": files.files[i] });
	}
}

var data = {
	"FirstName": $("#txtFirstName").val(),
	"LastName": $("#txtLastName").val(),
	"Gender": $("#txtGender").val(),
	"oNestedClass": JSON.stringify(stdDetails)
}

$.ajax({
	type: 'POST',
	url: apiurl,
	data: JSON.stringify(data),
	contentType: "application/json; charset=utf-8",
	dataType: 'json',
	success: function (d) {
		alert("Saved Successfully");
	},
	error: function () {
		alert("Error please try again");
	}
});

e.preventDefault();});

Try to use formdata to pass the file. Note we pass the data binded by name attribute, such us: saveDocs.oNestedClass[" + i + "].StdFile , to keep same as the api action parameter saveDocs.

I have a work demo like below, you can refer to it:

1.change your code like :

$("#postform").submit(function (e) {
var apiurl = "https://localhost:7019/api/NestClass/SaveDocuments";
var fileUpload = $(".uplFile");        
var formData = new FormData();
for (var i = 0; i < fileUpload.length; i++) {
var files = fileUpload[i];          
if (files.files.length > 0) {
debugger
formData.append("saveDocs.oNestedClass[" + i + "].StdFile", files.files[i]);
formData.append("saveDocs.oNestedClass[" + i + "].StdType", i);                                                         
}         
}
formData.append("saveDocs.FirstName", $("#txtFirstName").val());
formData.append("saveDocs.LastName", $("#txtLastName").val());
formData.append("saveDocs.Gender", $("#txtGender").val());
$.ajax({
type: 'POST',
url: apiurl,         
data: formData,
contentType: false,
processData: false,
success: function (d) {
alert("Saved Successfully");
},
error: function () {
alert("Error please try again");
}
});
e.preventDefault();      
});

2.add [FromForm] to recieve formdata

[HttpPost("SaveDocuments")]
public IActionResult SaveDocuments([FromForm]Documenttest saveDocs)
{
var docTypeList = docContext.SaveDocuments(saveDocs);
return Ok(docTypeList);
}

result: