Update or add a querystring param/value

ServiceStack #Script
1

I was looking that the url filters http://templates.servicestack.net/docs/default-filters#url-handling
as I was wanting to add or update a querystring param.

so my url could be anything really, I just want to preserve and update/append a specific qs param

e.g.
/somepath?qs1=1&qs2=2

{{ qs | setParam("qs", someObj) | assignTo: newQs }}

I see the qs is a NetCoreQueryStringCollection which is readonly so can’t add params.
The existing filters are more for building a url from scratch.

Am I missing something already exsting for handling this use case?

2

The new qs and query return the Request.QueryString collection, the URL Handling filters work on strings, which you can get by calling .ToString() on the collection, e.g:

{{ qs | toString | addQueryString({ qs3: 3}) | assignTo: newQs }}
1 Like
3

FYI to improve the experience a bit I’ve added queryString to return Request.QueryString.ToString()

{{ queryString | addQueryString({ qs3: 3 }) }}

You can also use addItem to add an item to a collection, inc. a Dictionary to a Dictionary, a KeyValuePair to a dictionary, etc then you can use the new toQueryString filter to generate the queryString, e.g:

{{ {a:1} | addItem({b:2}) | toQueryString }}

{{ {a:1} | addItem(pair('b',2)) | toQueryString }} //pair -> KeyValuePair<string,object>

Although it’s easier in these cases to use the object expression support directly, i.e:

{{ {a:1,b:2,...moreArgs} | toQueryString }}
1 Like
4

Thanks. I couldn’t quite get it to work with the above so I wrote the following filter.

{{ setQueryStringParam(qs, "param", "paramVal") | assignTo: newQs }}

public QueryString setQueryStringParam(NameValueCollection queryString, string param, string value)
{
    var qs = queryString == null ? new Dictionary<string, string>() : queryString.ToDictionary();
    if(value == null) qs.Remove(param);
    else
    {
        if (qs.ContainsKey(param))
            qs[param] = value;
        else
            qs.Add(param, value);
    }
    return QueryString.Create(qs);
}
5

ok no worries, glad you’ve found a solution. I wanted to ensure this scenario is well supported so I’ve added a new queryDictionary filter to return the QueryString in an Object Dictionary (so it can be queried/modified as a dictionary) and added support for NameValueCollection in underlying Dictionary conversion APIs, I’ve also changed toQueryString to prefix the QueryString with a ? which different URL Handling APIs were checking for.

Anyway there’s now a lot of ways to achieve the same result which you can test by replacing the URL Handling Live preview with:

http://templates.servicestack.net/docs/default-filters?qs1=1&qs2=2#url-handling

{{ `?${qs}` | addQueryString({ qs3:3}) }}
{{ queryString | addQueryString({ qs3:3}) }}
{{ qs | toObjectDictionary | addItem({ qs3:3 }) | toQueryString }}
{{ queryDictionary | addItem({ qs3:3 }) | toQueryString }}
{{ queryDictionary | addItem(pair('qs3',3)) | toQueryString }}

Which all return the same string result:

?qs1=1&qs2=2&qs3=3
?qs1=1&qs2=2&qs3=3
?qs1=1&qs2=2&qs3=3
?qs1=1&qs2=2&qs3=3
?qs1=1&qs2=2&qs3=3

As they all return a string they can be further manipulated with the various URL handling features:

{{ queryDictionary | addItem({ qs3:3 }) | toQueryString | addQueryString({ qs4:4 }) }}
{{ queryDictionary | addItem({ qs3:3 }) | toQueryString | setQueryString({ qs1:5 }) }}
{{ queryDictionary | addItem({ qs3:3 }) | toQueryString | addHashParams({ qs4:4 }) }}
{{ queryDictionary | toQueryString | addHashParams({qs4:4}) | setHashParams({qs4:5}) }}

Which returns:

?qs1=1&qs2=2&qs3=3&qs4=4
?qs1=5&qs2=2&qs3=3
?qs1=1&qs2=2&qs3=3#qs4=4
?qs1=1&qs2=2#qs4=5
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