Multiple queries not merged on expand to string

[DoCode]

Steps to reproduce

• Example 1:

  var result = UriTemplate.For("https://localhost:5000/api/resource{?key,value}{?id,name}")
                          .WithPartialExpand()
                          .ExpandToString();
  

• Example 2:

  var result = UriTemplate.For("https://localhost:5000/api/resource?key=mykey&value=myValue{?id,name}")
                          .WithPartialExpand()
                          .ExpandToString();
  

Expected behavior

• Example 1:

  result == "https://localhost:5000/api/resource{?key,value}{&id,name}"
  

  or

  result == "https://localhost:5000/api/resource{?key,value,id,name}"
  

• Example 2:

  result == "https://localhost:5000/api/resource?key=mykey&value=myValue{&id,name}"
  

Actual behavior

• Example 1:

  result == "https://localhost:5000/api/resource{?key,value}{?id,name}"
  

• Example 2:

  result == "https://localhost:5000/api/resource?key=mykey&value=myValue{?id,name}"
  

[letsar]

Hi @DoCode. I didn't designed the partial expand to merge such templates. Why do you need such things?

To me, you should have these templates:

• Example 1:

string uriString = UriTemplate.For("https://localhost:5000/api/resource{?key,value,id,name}")
                              .WithParameter("id", 10)
                              .WithPartialExpand()
                              .ExpandToString();
uriString.ShouldBeEquivalentTo("https://localhost:5000/api/resource?id=10{&key,value,name}");

• Example 2:

string uriString = UriTemplate.For("https://localhost:5000/api/resource?key=mykey&value=myValue{&id,name}")
                              .WithParameter("id", 10)
                              .WithPartialExpand()
                              .ExpandToString();
uriString.ShouldBeEquivalentTo("https://localhost:5000/api/resource?key=mykey&value=myValue&id=10{&name}");

You can see here that the ? operator can be transformed to the & operator automatically if we partially expand a {?a,b,c} query with any of the parameter provided.

[DoCode]

Hi @letsar,
thanks for your response. I need such things because I used this in an ASP.NET Core API for HAL links. The UrlHelper creates the links as a preprocessor for specified routes and after that, your lib expands this strings with RFC6570 templates. The best would be when the library worked out of the box with the UrlHelper ;-)

[letsar]

@DoCode thanks for this explanation. So if I understand correctly the UrlHelper creates url like "https://localhost:5000/api/resource{?key,value}{?id,name}"?

[DoCode]

@letsar sorry for the delay. No, I generate the links first, with the UrlHelper, based on the current request/response and then append the RFC6570 template parts with your libs.

[letsar]

Ok so you generate the part {?key,value}{?id,name}? Why don't you generate {?key,value,id,name} instead ?

[DoCode]

The problem is, that I don't know if the existing (pre-rendered via UrlHelper) already contains a query. Like this code snippet:

protected override Task EnrichModel(INameBaseModel content, IUrlHelper urlHelper)
{
    RouteValueDictionary routeData = urlHelper.GetRouteDataWithQuery();

    ...

    new Link(
             HttpActionVerb.PUT,
             UriTemplate.For(urlHelper.Link(urlHelper.ActionContext.ActionDescriptor.AttributeRouteInfo.Name, routeData) + "{&value}")
                        .WithPartialExpand()
                        .ExpandToString(),
             RelationType.Self
            );


    ...
}

[letsar]

Ok I understand now. UriTemplate must be a valid uri in the first place, so you will have to handle it yourself. If you want you can do that with an extension method and submit a pull request, so that it will be available for other people.