如何通过列表<mycustomclass>从controller来看如果不是表格？</mycustomclass>

Question

I have a Search page that is not a form, and it is simplified to the following.

My model is as follows:

public class SearchCategory
{
    public string Category { get; set; }
}
public class SearchViewModel
{
    public string Category { get; set; }
    public List<SearchCategory> Categories { get; set; }
}

In my view, my ActionLink is as follows:

@Html.ActionLink("Displaytext", "Search", "Explore", new { category = "SomeValue", categories = Model.Categories }, null)

My Controller's ActionResult is as follows:

public ActionResult Search(string category, List<SearchCategory> categories)
{
    SearchViewModel SearchModel = new SearchViewModel();
    if (category == null) { SearchModel.Category = "All Entries"; } else { SearchModel.Category = category; }

    if (SearchModel.Category == "All Entries")
    {
        SearchModel.Categories = new List<SearchCategory>();
    }
    else
    {
        SearchModel.Categories = categories;
    }

    SearchCategory c = new SearchCategory();
    c.Category = SearchModel.Category;
    if (SearchModel.Category != "All Entries")
    {
        if (SearchModel.Categories.Contains(c))
        {
            //do nothing, because the categories list already contains this category
        }
        else
        {
            SearchModel.Categories.Add(c);
        }
    }
    return View(SearchModel);
}

Within my controller's ActionResult , I am adding items to the categories list, and I am able to see this as a populated list if I put a breakpoint on the ActionLink when it re-enters the view. My problem is that the ActionResult receives a null instead of the populated list passed from the view when it re-enters the controller.

What am I doing wrong? Do I absolutely need to set this search page up as a form, or is there some way to get the view to pass the populated list back to the controller?

Answer 1

Good question... you have to deal with strings (not a class) cause ASP.NET doesn't convert it to standard HTTP GET Request

I made an example. Notice this "categories.categories[@i].Category" classes

public class SearchCategory
{
    public string Category { get; set; }
}
    public class SearchViewModel
{
    public List<SearchCategory> Categories { get; set; }
}

Here is my Method

        public ActionResult Search(string category, SearchViewModel categories)
    {
        if (categories == null) categories = new SearchViewModel { };
        if (categories.Categories == null) categories.Categories = new List<SearchCategory>();
        if (category != null) categories.Categories.Add(new SearchCategory { Category = category }); // add category to the list
        return View(categories);
    }

Here is View

 @model WebApplication6.Models.SearchViewModel @using WebApplication6.Models; @{ ViewBag.Title = "Index"; } <form> @{ int i = 0; if (Model.Categories.= null) { foreach (var item in Model.Categories) { <input type="hidden" name="categories.categories[@i].Category" value="@item;Category" /> i++. } } <input type="hidden" name="category" value="Abdallah Hiekal" /> <input type="submit" name="Click me." /> } </form> <.--print--> @if (Model.Categories.= null) { foreach (var item in Model.Categories) { <div> @item.Category <hr /> </div> } } <!--end print--> <h2>Index</h2> @Model.Categories.Count()