Shopping Cart is not working properly in Asp.netCoreRazor2.0

Question

Shopping Cart Page displays only one item in Asp.net Core 2.0 Razor Pages

 

There is a problem When I clicked on Add to cart Button ,only one item is displayed and previous one is deleted .I have four Boostrap tab,on every click I am passing tab&id .How to fix this problem I think its very simple but I am new in Asp.net Core.Any help it would be great appreciate.Following are more details about my appication, I've attached as a zip file.

 

This is my Index.cshtml file

<div class="tab4">
                    @foreach (var item in Model.FootwereList)
                    {
                        <div class="col-md-3 product-men">
                            <div class="men-pro-item simpleCart_shelfItem">
                                <div class="men-thumb-item">
                                    <img src="@Html.DisplayFor(modelItem => item.ImageaFront)" alt="" class="pro-image-front">
                                    <img src="@Html.DisplayFor(modelItem => item.ImageBack)" alt="" class="pro-image-back">
                                    <div class="men-cart-pro">
                                        <div class="inner-men-cart-pro">
                                            <a asp-page="/single" asp-route-tab="@item.tab" asp-route-id="@item.ProductID" class="link-product-add-cart">Quick Viewa>
                                        div>
                                    div>
                                    <span class="product-new-top">Newspan>

                                div>
                                <div class="item-info-product ">
                                    <h4><a href="single.html">@Html.DisplayFor(modelItem => item.ProductName)a>h4>
                                    <div class="info-product-price">
                                        <span class="item_price">[email protected](modelItem => item.OriginalPrice)span>
                                        <del>[email protected](modelItem => item.FalsePrice)del>
                                    div>
                                    <div class="snipcart-details top_brand_home_details item_add single-item hvr-outline-out button2">
                                        <form action="/shopping_Cart" method="post">

                                            fieldset>
                                        form>
                                    div>
                                    <div class="inner-men-cart-pro">
                                        <a asp-page="/shopping_Cart" asp-route-tab="@item.tab" asp-route-id="@item.ProductID" class="link-product-add-cart">Add to carta>
                                    div>
                                div>
                            div>
                        div>
                    }
                div>

This is my shopping_cart.cshtml file

@page
@model EliteShopping.Pages.Shopping.shopping_CartModel
@{
}
<h2 style="position:center;">Your Shopping Carth2>

    @*<p>
        <a asp-page="Customer">Create New Customera>
    p>*@
    <table class="table">
        <thead>
            <tr>
                <th>
                    @Html.DisplayName("Image")
                th>
                <th>
                    @Html.DisplayName("Name")
                th>
                <th>
                    @Html.DisplayName("Price")
                th>

            tr>
        thead>
        <tbody>
            @foreach (var item in Model.FootwereList)
            {
                <tr>
                    <td>
                        @Html.DisplayFor(modelItem => item.ImageaFront)
                    td>
                    <td>
                        @Html.DisplayFor(modelItem => item.ProductName)
                    td>
                    <td>
                        @Html.DisplayFor(modelItem => item.OriginalPrice)
                    td>

                    <td>
                        <a asp-page="./EditCustomer" asp-route-id="@item.ProductID">Edit Cart Itema> |
                        <a asp-page="./AllCustomer" onclick="return confirm('Are you sure you want to delete this item?');" asp-page-handler="Delete" asp-route-id="@item.ProductID">Delete Itema>
                    td>
                tr>
            }
        tbody>
    table>

This is my shopping_cart.csfile 

using EliteShopping.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using RazorPagesDemo.Models;
using System.Collections.Generic;
using System.Linq;

namespace EliteShopping.Pages.Shopping
{

    public class shopping_CartModel : PageModel
    {
        DatabaseContext _Context;
        public shopping_CartModel(DatabaseContext databasecontext)
        {
            _Context = databasecontext;
        }

        public List FootwereList { get; set; }

        [BindProperty]
        public Footwere Footwere { get; set; }


        public void OnGet(int id, string tab)

        {     //for Footwere
            var Footwere = (from FootwereList in _Context.FootwereTB
                            where FootwereList.ProductID == id & FootwereList.tab == tab
                            select FootwereList).ToList();

            FootwereList = Footwere;
        }



    }
 }