Ruby-on-rails – Add querystring parameters to link_to

query-stringruby-on-rails

I'm having difficultly adding querystring parameters to link_to UrlHelper. I have an Index view, for example, that has UI elements for sorting, filtering, and pagination (via will_paginate). The will_paginate plugin manages the intra-page persistence of querystring parameters correctly.

Is there an automatic mechanism to add the querystring parameters to a give named route, or do I need to do so manually? A great deal of research on this seemingly simple construct has left me clueless.

Edit

Some of the challenges:

If I have two querystring parameters, bucket & sorting, how do set a specific value to one of these in a link_to, while preserving the current value of the other? For example:
```
<%= link_to "0", profiles_path(:bucket => '0', :sorting=>?? ) %>
```
If I have multiple querystring parameters, bucket & sorting & page_size, and I want to set the value to one of these, is there a way to 'automatically' include the names and values of the remaining parameters? For example:
```
<%= link_to "0", profiles_path(:bucket => '0', [include sorting and page_size name/values here] ) %>
```
The will_paginate plugin manages its page variable and other querystring variables automatically. There doesn't seem to be an automatic UI element for managing page size. While I've seen code to create a select list of page sizes, I would rather have A elements for this (like SO). Part of this challenge is related to #2, part is related to hiding/showing this UI element based on the existence/non-existence of records. Said another way, I only want to include page-size links if there are records to page. Moreover, I prefer to automatically include the other QS variables (i.e. page, bucket, sorting), rather than having to include them by name in the link_to.

Best Answer

The API docs on link_to show some examples of adding querystrings to both named and oldstyle routes. Is this what you want?

link_to can also produce links with anchors or query strings:

link_to "Comment wall", profile_path(@profile, :anchor => "wall")
#=> <a href="/profiles/1#wall">Comment wall</a>

link_to "Ruby on Rails search", :controller => "searches", :query => "ruby on rails"
#=> <a href="/searches?query=ruby+on+rails">Ruby on Rails search</a>

link_to "Nonsense search", searches_path(:foo => "bar", :baz => "quux")
#=> <a href="/searches?foo=bar&amp;baz=quux">Nonsense search</a>

Related Solutions

Empty QueryString parameter

You can use null as the key for the NameValueCollection and it will give you a comma-delimited list of parameter names that don't have values.

For http://example.com?bar=3&foo you would use Request.QueryString[null] and it would retrieve foo.

If you have more than one parameter name without a value, it will give you a value that is comma-delimited.

For http://example.com?bar=3&foo&test you would get foo,test as a value back.

Update:

You can actually use Request.QueryString.GetValues(null) to get the parameter names that don't have values.

C# – Action with set of fixed parameters in url and a set of optional parameters either from post or from querystring

I just created sample application =>

controller:

 public class FooController : Controller
    {
        public ActionResult Bar
            (string fizz1, int fizz2, string fizz3, string fizz4, 
             string fizz5, int? fizz6)
        {
            var sb = new StringBuilder();

            sb.AppendLine(string.Format("{0} | {1} | {2} | {3} | {4} | {5}", 
                fizz1, fizz2, fizz3, fizz4, fizz5, fizz6.HasValue ? fizz6.Value.ToString():""));

            return Content(sb.ToString());
        }

    }

global.asax:

 public class MvcApplication : System.Web.HttpApplication
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            //routes.MapRoute(
            //    "Default",                                              // Route name
            //    "{controller}/{action}/{id}",                           // URL with parameters
            //    new { controller = "Home", action = "Index", id = "" }  // Parameter defaults
            //);

            routes.MapRoute(
                    "FooBar",
                    "{siteLanguage}/bar/{fizz1}/{fizz2}/{fizz3}/{fizz4}",
                    new { controller = "Foo", action = "Bar", fizz3 = "", fizz4 = "" }
            );

        }

        protected void Application_Start()
        {
            RegisterRoutes(RouteTable.Routes);
        }
    }

Results:

http://localhost:4038/en/bar/fizz1/2?fizz5=val&fizz6=1

returns

fizz1 | 2 | | | val | 1

Problem seems to be elsewhere. Are there any filters/model binders doing something?

Best Answer

Related Solutions

Empty QueryString parameter

C# – Action with set of fixed parameters in url and a set of optional parameters either from post or from querystring

Related Topic