API returning 400 Bad Request response - api

Question

I have built an API and an application that uses that API. Everything was working but now, for some reason, I get a 400 Bad Request response. I am not sure if I changed something in the code so I wanted to double check it was correct.
So my API call is this
$client = new GuzzleHttp\Client();
$jsonData = json_encode($data);
$req = $client->request('POST', 'https://someurl.com/api/v1/createProject', [
'body' => $jsonData,
'headers' => [
'Content-Type' => 'application/json',
'Content-Length' => strlen($jsonData),
]
]);
$output = $req->getBody()->getContents();
The API has a route set up correctly which uses post. The function it calls is correct, and I have changed it for testing to simply return
return response()->json(["Success", 200]);
When I test the API out within Postman, I can see that Success is returned. When I test the API within the other application I have built, I dont even see a POST request within the console, I am just displayed a Laravel error 400 Bad Request.
What could be the cause of this issue?
Thanks
Update
I have changed the request to this
$data= json_encode($data);
$req = $client->post('https://someurl.com/api/v1/createProject', [
'body' => $data
]);
If I output $data after it has been encoded, I get something like this
{
"projectName":"New Project",
"clientName":"Test Client",
}
Within the controller function of the API that is being called, I simply do
return response()->json(['name' => $request->input('clientName')]);
The 400 error has now gone, but I now get null returned to me
{#326 ▼
+"name": null
}
Request is being injected into the function as it should be. Should I be returning the data in a different way?
Thanks

Answer 1

Probably you did $ composer update and Guzzle updated.
So if you are using newest Guzzle (guzzlehttp/guzzle (6.2.2)) you do POST request:
$client = new GuzzleHttp\Client();
$data = ['name' => 'Agent Smith'];
$response = $client->post('http://example.dev/neo', [
'json' => $data
]);
You do not need to specify headers.
To read response you do following:
$json_response = json_decode($response->getBody());
My full example (in routes file web.php routes.php)
Route::get('smith', function () {
$client = new GuzzleHttp\Client();
$data = ['name' => 'Agent Smith'];
$response = $client->post('http://example.dev/neo', [
'json' => $data,
]);
$code = $response->getStatusCode();
$result = json_decode($response->getBody());
dd($code, $result);
});
Route::post('neo', function (\Illuminate\Http\Request $request) {
return response()->json(['name' => $request->input('name')]);
});
or you could use following (shortened), but code above is "shorter"
$json_data = json_encode(['name' => 'Agent Smith']);
$response = $client->post('http://example.dev/neo', [
'body' => $json_data,
'headers' => [
'Content-Type' => 'application/json',
'Content-Length' => strlen($json_data),
]
]);
note: If you are running PHP5.6, change always_populate_raw_post_data to -1 (or uncomment the line) in php.ini and restart your server. Read more here.

Answer 2

In my case I was using public IP address in BASE_URL while I should have been using the private IP. From mac you can get your IP by going into system preferences -> network.
This is with Android + Laravel (API)