How to add a Macro to the Laravel HTTP client facade

While working on Let Them Eat I came across some peculiar behavior. For some of the Slack web API’s, there is a requirement to send the requests as a URL encoded form object. Since all of their API endpoints support this method of access, I created a little helper on my user object to get an instance of the Laravel HTTP client, with the asForm() method already applied.

This was working great until today when I wanted to add support for blocks to one of my bot responses. While I could support sending that field as a JSON string, it felt better to change the request to be sent fully as JSON instead. I thought, that would be as simple as calling ->withHeaders() again, but unfortunately, the deep-recursive-merge used by the HTTP facade doesn’t clear out any existing values.

Http::asForm()->asJson()  

"headers" => [    
    "Content-Type" => [      
         0 => "application/x-www-form-urlencoded",      
         1 => "application/json"    
    ]
]

Obviously, the best option would be to not call the facade with multiple methods that change the same object, but in this case I really wanted to just overwrite it for this one instance.

Enter, Macros!

There are lots of places online to read about Laravel Macros so I won’t go into it here too deeply, but the gist of it, is you can add custom methods to core objects without extending them and creating new classes. This can be super helpful when you just want to add a little helper method but don’t want to go through the process of extending the class the old-fashion way. This can be especially useful to access protected properties or private methods.

I knew all facades in Laravel are macroable so I jumped into my AppServiceProvider boot method and added a lil somthin somethin.

// within AppServiceProvider::boot()  
PendingRequest::macro('clearContentType', function () {    
    $this->options['headers']['Content-Type'] = [];    
    return $this;  
});

Originally, I tried to add the Macro directly to the Http facade, but that only ended up working if I called the new method statically. To have it work in the manner I expected, I had to add the macro to Illuminate\Http\Client\PendingRequest, which is the class that is bound to the Http facade under the hood.

Using my new macro, I can easily clear out any content type headers before making a request, no matter how many times I call methods that set the content type header.

Http::asForm()->asJson()->asForm()->asJson()->asForm()->clearContentType()->asJson()  

"headers" => [    
    "Content-Type" => [      
        0 => "application/json"    
    ]  
]

Now, I suspect this is a bug, but I’m not sure. I’ll be opening an issue on Github and we shall see. In the meantime, the macro will have to do!