how to append nested object to FormData with .net core and angular 8 - angular8

Question

I am developing an application using angular as frontend and API in .net core.
My API model is as below:
class Tag
{
public int ID {get;set;}
public string Name {get;set;}
public string Description {get;set;}
}
And the Post class is as below
class Post
{
public int ID {get;set;}
..... //other properties
public IEnumerable<Tag> Tags {get;set;}
}
The same class I am having in angular as well.
Here I have to upload image and other properties with tags as well.
const formData = new FormData();
if(blogRequest.imageContent){
formData.append('file', postRequest.imageContent, postRequest.imageContent.name);
}
formData.append("Title",postRequest.title);
.... // appended other data as well
///formData.append("Tags",tags); <-- how do I append tag object here. JSON.Stringify(tags) is not working as it is not assigning in the api model. I have to manually deserialize to object which I don't want.
I have tried below
var tags:Tag[]=[];
var t1 = new Tag();
t1.Name="some";
t1.ID=0;
t1.Description="desc";
var t2 = new Tag();
t2.Name="some";
t2.ID=0;
t2.Description="desc";
tags[0] =t1;
tags[1] = t2;
formData.append("Tags[]","{Name:some}");
formData.append("Tags[]","{Name:something}");
formData.append("Tags[].Name","some");
formData.append("Tags[].Name","something");
Non of them worked. The tags is passing as array when I debug and watch the Request.Form but it is not assigning to the object. The Tags count is always 0.
I can provide more info if needed. thanks in advance.