javascript - Shippo:在其他函数中使用生成的事务的label_url变量

我希望在node中使用shippo的api有更多经验的人能帮助我解决这个问题。
我的最终目标是按下角形表单前端的按钮，创建发货事务，并使用事务的标签url创建自定义pdf。除了将生成的标签url推送到pdf模板之外，一切都正常。
首先，我将Shippo's single click label creation example粘贴到快件路线中。它工作得很好，生成事务，我可以通过ping shippo的api查看最近的事务列表并查看最近的事务。
然后，我添加了lines 102-111 of this code example并用它替换了instalabel代码中的通用错误消息生成器，因此我当前的app.js shippo事务逻辑如下所示：

shippo.transaction.create({
    "shipment": shipment,
    "carrier_account": "xxxxxxxxxxxxxxxxxxxxxx",
    "servicelevel_token": "ups_ground",
    "label_file_type": "PNG"
},function(transaction, err ){
            console.log("transaction : %s", JSON.stringify(transaction, null, 4));
            // print label_url and tracking_number
            if(transaction.object_status == "SUCCESS") {
                console.log("Label URL: %s", transaction.label_url);
                console.log("Tracking Number: %s", transaction.tracking_number);
                exports.label_url = transaction.label_url;
                exports.tracking_number = transaction.tracking_number;
            }else{
                //Deal with an error with the transaction
                console.log("Message: %s", transaction.messages);
            }

    });

我需要获取刚刚创建的事务的标签url和跟踪号，并在另一个函数中使用它，但迄今为止我尝试的所有操作似乎都会出现如下错误：

/src/app.js:88
    if(transaction.object_status == "SUCCESS") {
                  ^

TypeError: Cannot read property 'object_status' of null

我猜这是因为创建发货标签的函数没有导出shippo发送回来的响应，所以我不能在其他函数中使用它…是准确的，还是我找错树了？作为参考，Shippo的回答应该是这样的：

{
   "object_state":"VALID",
   "object_status":"SUCCESS",
   "object_created":"2014-07-25T02:09:34.422Z",
   "object_updated":"2014-07-25T02:09:34.513Z",
   "object_id":"ef8808606f4241ee848aa5990a09933c",
   "object_owner":"[email protected]",
   "was_test":true,
   "rate":"ee81fab0372e419ab52245c8952ccaeb",
   "tracking_number":"tracking_number_goes_here",
   "tracking_status":null,
   "tracking_url_provider":"",
   "label_url":"label_url_goes_here",
   "commercial_invoice_url": "",
   "messages":[

   ],
   "customs_note":"",
   "submission_note":"",
   "metadata":""
}

如何在shippo.transaction.create函数本身之外使用此响应中的值？
谢谢你的阅读。

最佳答案

传递给shippo.transaction.create中使用的回调的参数的注入参数是相反的。它应该是(err, transaction)而不是(transaction, err)。或者，您可以链接.then()并传递一个只接受(transaction)并访问transaction.messages中任何错误消息的回调。
下面是本文撰写时最新版本的shippo-node-wrapper的工作示例。

var shippo = require('./lib/shippo')('<API KEY>');

var addressFrom  = {
    "object_purpose":"PURCHASE",
    "name":"Ms Hippo",
    "company":"Shippo",
    "street1":"215 Clayton St.",
    "city":"San Francisco",
    "state":"CA",
    "zip":"94117",
    "country":"US", //iso2 country code
    "phone":"[phone]",
    "email":"[email protected]",
};

// example address_to object dict
var addressTo = {
    "object_purpose":"PURCHASE",
    "name":"Mr Hippo",
    "company":"Happy Hippo",
    "street1":"965 Mission St",
    "street2":"Suite 425",
    "city":"San Francisco",
    "state":"CA",
    "zip":"94103",
    "country":"US", //iso2 country code
    "phone":"949-123-4567",
    "email":"[email protected]",
    "metadata" : "Hippo T-Shirt Order #1043"
};

// parcel object dict
var parcel = {
    "length":"5",
    "width":"5",
    "height":"5",
    "distance_unit":"in",
    "weight":"2",
    "mass_unit":"lb",
};

var shipment = {
    "object_purpose": "PURCHASE",
    "address_from": addressFrom,
    "address_to": addressTo,
    "parcel": parcel,
    "async": false
};

shippo.transaction.create({
    "shipment": shipment,
        "carrier_account": "07280f4f96f34cc8b75e593c4835dc38",
        "servicelevel_token": "usps_priority",
        "label_file_type": "PNG"
}, function (err, transaction) {
    console.log("transaction : %s", JSON.stringify(transaction, null, 4));
    // print label_url and tracking_number
    if (transaction.object_status == "SUCCESS") {
        console.log("Label URL: %s", transaction.label_url);
        console.log("Tracking Number: %s", transaction.tracking_number);
    } else {
        //Deal with an error with the transaction
        console.log("Message: %s", transaction.messages);
    }
});

// OR

shippo.transaction.create({
    "shipment": shipment,
        "carrier_account": "07280f4f96f34cc8b75e593c4835dc38",
        "servicelevel_token": "usps_priority",
        "label_file_type": "PNG"
}).then(function (transaction) {
    console.log("transaction : %s", JSON.stringify(transaction, null, 4));
    // print label_url and tracking_number
    if (transaction.object_status == "SUCCESS") {
        console.log("Label URL: %s", transaction.label_url);
        console.log("Tracking Number: %s", transaction.tracking_number);
    } else {
        //Deal with an error with the transaction
        console.log("Message: %s", transaction.messages);
    }
});