ASP.NET Core routing with RouteValueDictionary

问题

I need to create Tag helper to generate url from form with multi select. I remember, in older mvc I could use something like this:

var i = 0;
foreach (var attribute in PaginatorFilterItems)
{                    
    foreach (var attributeFilter in attribute.Value)
    {
        routeValues.Add($"{attribute.Key}[{i++}]", attributeFilter.ToString());          
    }
    i=0;
}    

Now, I can use it in Url.Action(..., ..., routeValues) helper and got something like this:

?str=val1&str=val2 etc.

But in dotnet core I get some escape sequence. I'm not sure why:

?str%5B0%5D=val1&str%5B1%5D=val2

[] are escaped and not binded to route. How can I fix it. I need correct collection format:

?str=val1&str=val2&str=val3 ...

Thank you for your time.

EDIT:

Now it is working. But for this example I didn't use RouteValueDictionary but string list and Join method.

public class PaginatorPageTagHelper : TagHelper
    {
        public IDictionary<string, ICollection> PaginatorFilterItems { get; set; }

        public string PaginatorController { get; set; }
        public string PaginatorAction { get; set; }
        public string PaginatorTitle { get; set; }
        public int PaginatorPageNumber { get; set; }
        public string PaginatorPageAttributeName { get; set; }
        public string PaginatorAttributeCategory { get; set; }

        public string PaginatorTagName { get; set; }
        public IUrlHelper PaginatorUrlHelper { get; set; }

        public override void Process(TagHelperContext context, TagHelperOutput output)
        {
            if(PaginatorUrlHelper == null) {
                throw new NullReferenceException("UrlHelper parameter cannot be null.");
            }

            var attributeList = new List<string>();            
            var routeValues = new RouteValueDictionary();

            if (!string.IsNullOrEmpty(PaginatorAttributeCategory) && PaginatorFilterItems.ContainsKey(PaginatorAttributeCategory) && PaginatorFilterItems[PaginatorAttributeCategory].Count == 1)
            {
                routeValues.Add(PaginatorAttributeCategory, PaginatorFilterItems[PaginatorAttributeCategory].Cast<string>().First());                                    
            }
            else
            {                
                foreach (var attribute in PaginatorFilterItems)
                {                    
                    foreach (var attributeFilter in attribute.Value)
                    {
                        attributeList.Add($"{attribute.Key}={attributeFilter.ToString()}");
                    }                    
                }             
            }

            //can be <a> ,<link> or custom
            output.TagName = PaginatorTagName ?? "a";
            output.Content.SetContent(PaginatorTitle);            
            routeValues.Add("page", string.Empty);               

            if (PaginatorPageNumber > 1)
            {
                routeValues["page"] = PaginatorPageNumber;                
            }

            // create fallback for clasic filter, for example: /example?str=val1&str=val2
            if (attributeList.Any())
            {                
                output.Attributes.SetAttribute("href", $"{this.GetPaginatorUrl(routeValues)}?{string.Join("&", attributeList)}");
                return;
            }           

            output.Attributes.SetAttribute("href", this.GetPaginatorUrl(routeValues));
        }

        private string GetPaginatorUrl(RouteValueDictionary routeValues) {
            return PaginatorUrlHelper.Action(PaginatorAction, PaginatorController, routeValues);
        }
    }

回答1:

I suspect that your helper returns an MvcHtmlString, which will be encoded when it's rendered in the view. If so, simply return a plain string instead. You'll need to make sure that you URL encode your values manually but it won't be encoded when rendered.

回答2:

You can use tag helpers like:

<a asp-area="" asp-controller="" asp-action="" asp-route-property1="value1" asp-route-property2="value2">my link</a> and so on.

来源：https://stackoverflow.com/questions/42461590/asp-net-core-routing-with-routevaluedictionary