Laravel 5.4 won't validate JSON - json

Question

I'm using Laravel 5.4 and trying to validate JSON in my POST request however the validator fails stating that the JSON isn't valid, even though it is. I'm assuming I'm not understanding the validation rules correctly and my implementation is wrong, rather than a bug or something else.
I have a simple POST endpoint which has both the Accept and Content-Type headers set to application/json.
In my POST request (testing using Postman) I'm supplying RAW data.
{
"only_this_key": { "one": "two" }
}
In my controller method I have the following:
// I'm using intersect to remove any other parameters that may have been supplied as this endpoint only requires one
$requestData = $request->intersect(['only_this_key']);
$messages = [
'only_this_key.required' => 'The :attribute is required',
'only_this_key.json' => 'The :attribute field must be valid JSON',
];
$validator = \Validator::make($requestData, [
'only_this_key' => 'required|json',
], $messages);
if ($validator->fails()) {
return new APIErrorValidationResponse($request, $validator);
}
return response()->json(['all good' => 'here']);
The error I get back is The inventory field must be valid JSON even though it is!
Passing in the raw data using Postman
{
"only-this-key": {
"item-one": "one",
"item-two": "two",
"item-three": "three"
},
"not": "wanted"
}
When I use dd($request->all()); within the method
array:2 [
"what-i-want" => array:3 [
"item-one" => "one"
"item-two" => "two"
"item-three" => "three"
]
"not" => "wanted"
]

Answer 1

The problem is with how Laravel is interpreting the raw data in the request. If you run dd($request->all()) in your controller you will see this output:
array:1 [
"{"only_this_key":{"one":"two"}}" => ""
]
Your entire JSON string is getting set as a key with a value of an empty string. If you absolutely must send it as raw data, then you're going to have to grab that key value and save it to an array with the key that you want. This should work (instead of the intersect line).
$requestData = ['only_this_key' => key($request->all())];
Alternatively, you can just send the body as x-www-form-urlencoded with your entire JSON string as the only value for one key.