"Cannot parse server response" with HTTP 204 about siesta

[joaomvfsantos]

@pcantrell I'm having the same issue, on my side I can't do anything about the server so I was looking to do something like the work around you suggested. Seems the syntax is for a deprecated version of Siesta. I'm adding the ChangeEmptyResponseContentType transformer like the below, but still have Siesta returning me the "Cannot parse server response" error.

configure(configurer: { (configuration) in
     configuration.pipeline[.rawData].add(ChangeEmptyResponseContentType())
     configuration.pipeline[.rawData].cacheUsing(PersistentCache<Data>())
     configuration.headers["Authorization"] = self.headers["Authorization"]
})

PersistentCache is my implementation of EntityCache I'm using and the Authorization header, well, it's just an Authorization header. Any ideas?

Thank you!

[pcantrell]

This should be fixed in the next beta release.

If you’re brave and foolhardy, try master and see if it’s fixed for you already.

[pcantrell]

Wait, apologies, I mistook this for another bug. I should have looked at your log more carefully before answering.

It looks like your server is sending Content-Type: application/json even though the response is empty. That’s causing Siesta to attempt to parse the response as JSON, which gives the “no value” error you’re seeing.

A 204 should not give a content-type header, since there is no content. Is that something you have control over?

[shaneneuerburg]

The library used for the scaffolding of the API is Restler (PHP), which apparently doesn't abide by that rule. I'll post an issue with them and see if I can override that for now.

[pcantrell]

If they're unable to change it, feel free to reopen this issue, and we'll either decide to make Siesta handle it as a special case or get you a configuration workaround.

[pcantrell]

Seeing that you’ve only got a workaround from the Restler side, I’ll give you a Siesta-side workaround to choose from as well.

You can make a response transformer that assigns a made-up content-type to empty responses to suppress further processing:

struct ChangeEmptyResponseContentType: ResponseTransformer
    {
    func process(response: Siesta.Response) -> Siesta.Response
        {
        switch(response)
            {
            case .Success(var entity):
                if let data = entity.content as? NSData where data.length == 0
                    { entity = Entity(content: NSData(), contentType: "unknown/empty") }
                return .Success(entity)

            case .Failure:
                return response
            }
        }
    }

…and then, when configuring your service, make it the first transformer in the pipeline:

configure
    {
    $0.config.responseTransformers.add(
        ChangeEmptyResponseContentType(),
        first: true)
    }

That’s just a hack, but it does give you another option if the Restler patch doesn’t suit.

[shaneneuerburg]

Great, thank you!