[#705] remove_url_params supports multiple params

Sometimes is useful to remove more than one parameter from the URL to
clear a filter. This change does not modify any logic, just adds support
for the first parameter being a list instead of a string.

The value and replace parameters only will apply to the first element of
the list (or the provided param if key is a string)

ckan/lib/helpers.py

@@ -1129,13 +1129,16 @@ def add_url_param(alternative_url=None, controller=None, action=None,
     return _create_url_with_params(params=params, controller=controller,
                                    action=action, extras=extras)
 
-
 def remove_url_param(key, value=None, replace=None, controller=None,
                      action=None, extras=None, alternative_url=None):
-    ''' Remove a key from the current parameters. A specific key/value
-    pair can be removed by passing a second value argument otherwise all
-    pairs matching the key will be removed. If replace is given then a
-    new param key=replace will be added.
+    ''' Remove one or multiple keys from the current parameters.
+    The first parameter can be either a string with the name of the key to
+    remove or a list of keys to remove.
+    A specific key/value pair can be removed by passing a second value
+    argument otherwise all pairs matching the key will be removed. If replace
+    is given then a new param key=replace will be added.
+    Note that the value and replace parameters only apply to the first key
+    provided (or the only one provided if key is a string).
 
     controller action & extras (dict) are used to create the base url
     via url_for(controller=controller, action=action, **extras)
@@ -1144,14 +1147,20 @@ def remove_url_param(key, value=None, replace=None, controller=None,
     This can be overriden providing an alternative_url, which will be used
     instead.
     '''
+    if isinstance(key, basestring):
+      keys = [key]
+    else:
+      keys = key
+
     params_nopage = [(k, v) for k, v in request.params.items() if k != 'page']
     params = list(params_nopage)
     if value:
-        params.remove((key, value))
+        params.remove((keys[0], value))
     else:
-        [params.remove((k, v)) for (k, v) in params[:] if k == key]
+        for key in keys:
+          [params.remove((k, v)) for (k, v) in params[:] if k == key]
     if replace is not None:
-        params.append((key, replace))
+        params.append((keys[0], replace))
 
     if alternative_url:
         return _url_with_params(alternative_url, params)