RouteUrl with querystring - with duplicate keys

Question

I use this extension to create an RouteUrl with the current query-string appended to it. This works fine for query-strings which does not have the same key twice or more.

public static string CurrentQueryStringRouteUrl(this UrlHelper url, string routeName, RouteValueDictionary routeValues)
{
    var context = url.RequestContext;
    var combinedRouteValues = new RouteValueDictionary();
    var queryString = context.HttpContext.Request.QueryString;

    foreach (var key in queryString.AllKeys.Where(key => key != null))
    {
        combinedRouteValues[key] = queryString[key];
    }

    if (routeValues != null)
    {
        foreach (var routeValue in routeValues)
        {
            combinedRouteValues[routeValue.Key] = routeValue.Value;
        }
    }

    return url.RouteUrl(routeName, combinedRouteValues);
}

When there is query-string keys of same name, e.g. ?id=1&id=2&id=3, this is converted into ?id=1,2,3 using the method above. Is there any way to avoid that? I wish to keep the original query-string as I am binding these values on a model list.

I am aware I can create a custom model-binder to bind the comma separated string to string[] (or int[] in this example) but I wish to avoid this as far of consistence goes.

score 0 · Accepted Answer · edited May 23 '17 at 11:59

0

You can to do this, but it is dirty hack:

string _rawstring = context.HttpContext.Request.RawUrl;
int _f;
_f = _rawstring.IndexOf('?');
string _resultString = _rawstring.SubString(_f, _rawstring.Length);

Here you can find helpful info about that problem: How to deal with more than one value per key in ASP.NET MVC 3?

edited May 23 '17 at 11:59

Community

1
1

answered Apr 21 '15 at 07:09

SpookyBookie

24
4

I just don't get why form POST and GET values is not combined as comma separated strings then. If I have a `select` element, with `multiple` set, the form submit result in `?id=1&id=2&id=3` – janhartmann Apr 21 '15 at 07:14
Try this: QueryString.AllKeys.InvalidateCachedArrays() – SpookyBookie Apr 21 '15 at 07:22
You get an array of non-cached keys. – SpookyBookie Apr 21 '15 at 07:42
1

I'll try it out on a few hours time, I return with how it go :-) – janhartmann Apr 21 '15 at 07:43
Thanks :-) WOrking on this in a few hours time and I see if I can get it to work :-) – janhartmann Apr 21 '15 at 08:19
I ended up creating a modelbinder for the string[]. – janhartmann Apr 22 '15 at 12:28

score 0 · Answer 2 · answered Dec 16 '17 at 10:03

I took a slightly different approach, because I really needed separate duplicated keys in my query string. I alter the key using a counter, and then after rendering the url string, I restore the original parameter names. I needed this for GridMvc's grid_filter queries, but you can adapt it for your purpose.

/// <summary>
/// Allows you to create or extend a collection of route values to use in a url action
/// </summary>
public class RouteValueBuilder
{
    readonly RouteValueDictionary routeValues;
    private int gridFilterCounter = 0;

    public RouteValueBuilder(object existingRouteValues = null)
    {
        routeValues = existingRouteValues as RouteValueDictionary ?? new RouteValueDictionary(existingRouteValues);
    }

    public void Add(string field, object value)
    {
        if (field == "grid_filter" && routeValues.ContainsKey(field))
        {
            // Because we can't add duplicate keys and GridMvc doesn't support joined comma format for query strings,
            // we briefly rename each new filter, and then the Finalise method must be called after the url
            // string is rendered to restore the grid_filter names back to normal.
            gridFilterCounter++;
            routeValues.Add(field + gridFilterCounter, value);
        }
        else if (routeValues.ContainsKey(field))
        {
            // Since duplicate key names are not supported, the concatenated comma approach can be used
            routeValues[field] += "," + value;
        }
        else
        {
            routeValues.Add(field, value);
        }
    }

    public RouteValueDictionary Get()
    {
        return routeValues;
    }

    /// <summary>
    /// Cleans up the final string url, fixing workarounds done during the building process.
    /// This must be called after the final url string is rendered.
    /// </summary>
    public static string Finalise(string url)
    {
        // Restores grid_filter parameters to their correct naming.  See comments on Add method.
        for (var i = 0; i < 100; i++)
        {
            url = url.Replace("grid_filter" + i, "grid_filter");
        }

        return url;
    }
}

Usage:

var builder = new RouteValueBuilder();
builder.Add("grid_filter", "value1");
builder.Add("grid_filter", "value2");
string url = Html.Action("Index", "Home", builder.Get());
url = RouteValueBuilder.Finalise(url);

Edit: Note that the comma concatenation approach actually doesn't work in the class because it gets encoded, but the support for duplication is the main taker from this example.

RouteUrl with querystring - with duplicate keys

2 Answers2