ASP.NET Core MVC filtering: How can I send multiple value to action?

Question

I want to filter products in my e-commerce project, but I have a problem: I want my filtering to change dynamically, I choose a brand from the selected list and the necessary filtering is done. When the second filter is done, my first filter is reset and the last filtering becomes valid.

I need such a URL structure:

/?SelectedVendor=Asus&SelectedMemory=4+GB

FilterViewModel.cs

public class FilterViewModel
    {
        public List<string> Vendors { get; set; }
        public List<string> Memories { get; set; }
        public string SelectedVendor { get; set; }
        public string SelectedMemory { get; set; }
    }

CategoryController.cs

    [HttpGet]
    public ViewResult Gaming(int productPage = 1, FilterViewModel model=null)
    {
        
        ProductListViewModel productList = new ProductListViewModel()
        {
            Products =
                _productService.GetProductsByCategoryId(1).OrderBy(p => p.Id).Skip((productPage - 1) * pageSize).Take(pageSize),
            FilterTypes = new FilterViewModel()
            {
                Vendors = _productService.Products.Select(I => I.Vendor).Distinct().OrderBy(I => I).ToList(),
                Memories = _productService.Products.Select(I => I.MemoryCapacity).Distinct().OrderBy(I => I).ToList(),
            }
        };


        if (!string.IsNullOrEmpty(model.SelectedVendor))
        {
            productList.Products = productList.Products.Where(I => I.Vendor.Contains(model.SelectedVendor));
            productList.FilterTypes.Memories = productList.Products.Select(I => I.MemoryCapacity).Distinct()
                .OrderBy(I => I).ToList();
        }

        if (!string.IsNullOrEmpty(model.SelectedMemory))
        {
            productList.Products = productList.Products.Where(I => I.MemoryCapacity == model.SelectedMemory);
        }

        return View(productList);
    }

FilterPartial.cshtml

<div class="col-md-3">
        <div class="filter filter-first">
            <h6 class="font-weight-bold">Brand</h6>

            <form method="get" asp-controller="@controllerName" asp-action="@actionName">

                @foreach (var vendor in Model.Vendors)
                {
                    <div class="mt-2 mb-2 pl-2">
                        <input type="submit" value="@vendor" asp-for="SelectedVendor"/>
                    </div>
                }


                <h6 class="font-weight-bold">Memory</h6>
                @foreach (var memory in Model.Memories)
                {
                    <div class="mt-2 mb-2 pl-2">
                        <input type="submit" asp-for="SelectedMemory" value="@memory"/>
                    </div>
                }
            </form>

        </div>
    </div>

Answer 1

Here is a demo to pass both SelectedVendor and SelectedMemory to action:

TestFilter.cshtml:

@await Html.PartialAsync("Partial", Model.FilterTypes)
<script>
    function addSelectedVendor(i) {
        $("#SelectedVendor").val($(i).val());
        $("#form1").submit();
    }
    function addSelectedMemory(i) {
        $("#SelectedMemory").val($(i).val());
        $("#form1").submit();
    }
    </script>

Partial.cshtml:

<form id="form1" method="get" asp-controller="Test" asp-action="TestFilter">

    @foreach (var vendor in Model.Vendors)
    {
        <div class="mt-2 mb-2 pl-2">
            <input type="button" value="@vendor" onclick="addSelectedVendor(this)" />
        </div>
    }


    <h6 class="font-weight-bold">Memory</h6>
    @foreach (var memory in Model.Memories)
    {
        <div class="mt-2 mb-2 pl-2">
            <input type="button" value="@memory" onclick="addSelectedMemory(this)" />
        </div>
    }
    <input hidden asp-for="SelectedVendor"/>
    <input hidden asp-for="SelectedMemory"/>
</form>

TestController(I use fake data to test):

 [HttpGet]
            public IActionResult TestFilter(FilterViewModel model)
            {
                ProductListViewModel productList = new ProductListViewModel {  FilterTypes=new FilterViewModel()};
                productList.FilterTypes.Vendors = new List<string> { "Apple", "Asus", "Dell", "Lenovo", "MSI" };
                productList.FilterTypes.Memories = new List<string> { "16GB", "4GB", "8GB"};
    
                return View(productList);
            }

result:

Answer 2

You can filter by list in your get method.

you should change get method like that

   public virtual IEnumerable<TEntity> Get(
        Expression<Func<TEntity, bool>> filter = null,
        Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
        string includeProperties = "")
    {
        IQueryable<TEntity> query = DbSet;

        if (filter != null) query = query.Where(filter);

        if (includeProperties != null)
            foreach (var includeProperty in includeProperties.Split
                (new[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
                query = query.Include(includeProperty);


        if (orderBy != null)
            return orderBy(query).ToList();
        return query.ToList();
    }