你可以使用硬编码的json属性作为键，或者你可以方便地使用GuzzleHttp\RequestOptions:: json常量。

下面是使用硬编码的json字符串的例子。

use GuzzleHttp\Client;

$client = new Client();

$response = $client->post('url', [
    'json' => ['foo' => 'bar']
]);

见文档。

对于Guzzle <= 4:

这是一个原始的post请求，所以把JSON放在body中解决了这个问题

$request = $this->client->post(
    $url,
    [
        'content-type' => 'application/json'
    ],
);
$request->setBody($data); #set body!
$response = $request->send();

上述答案对我来说并不管用。但这对我来说很好。

 $client = new Client('' . $appUrl['scheme'] . '://' . $appUrl['host'] . '' . $appUrl['path']);

 $request = $client->post($base_url, array('content-type' => 'application/json'), json_encode($appUrl['query']));

对于《Guzzle 5》，《Guzzle 6》和《Guzzle 7》，你是这样做的:

use GuzzleHttp\Client;

$client = new Client();

$response = $client->post('url', [
    GuzzleHttp\RequestOptions::JSON => ['foo' => 'bar'] // or 'json' => [...]
]);

Docs

简单地使用它将工作

   $auth = base64_encode('user:'.config('mailchimp.api_key'));
    //API URL
    $urll = "https://".config('mailchimp.data_center').".api.mailchimp.com/3.0/batches";
    //API authentication Header
    $headers = array(
        'Accept'     => 'application/json',
        'Authorization' => 'Basic '.$auth
    );
    $client = new Client();
    $req_Memeber = new Request('POST', $urll, $headers, $userlist);
    // promise
    $promise = $client->sendAsync($req_Memeber)->then(function ($res){
            echo "Synched";
        });
      $promise->wait();

$client = new \GuzzleHttp\Client(['base_uri' => 'http://example.com/api']);

$response = $client->post('/save', [
    'json' => [
        'name' => 'John Doe'
    ]
]);

return $response->getBody();