https://api.weixin.qq.com/union/promoter/product/generate?access_token=ACCESS_TOKEN

小程序联盟，获取商品推广素材接口求报错

{"errcode":200002,"errmsg":"pid cannot be empty rid: 6082c4eb-65f7ca31-4c3a561c"}

我POST的数据格式是：$data = '{"pid":"oBGYD5L8qqyUaFh5ZVRwHFnA0FWs_1131008663","productList":[{"productId":"2871088","appId":"wx6854bfe0efddf0f5","customizeInfo":"aaa"}]}';

这个数据格式有问题吗？