无法将未定义或空值转换为对象的错误

Question

我最近在这里无法启动代码，导致无法将undefined或null转换为object导致错误：

Utils.getCardsInSets((ERR, DATA) => {
    if (!ERR) {
        allCards = DATA;
        console.log("Card data loaded. [" + Object.keys(DATA).length + "]");
    } else {
        console.log("An error occurred while getting cards: " + ERR);
    }
});

控制台上显示的错误

console.log("Card data loaded. [" + Object.keys(DATA).length + "]");
                                                   ^

TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at Utils.getCardsInSets (/root/test/index.js:37:52)
    at Request.request [as _callback] (/root/test/utils.js:41:13)
    at Request.self.callback (/root/test/node_modules/request/request.js:186:22)
    at emitTwo (events.js:125:13)
    at Request.emit (events.js:213:7)
    at Request.<anonymous> (/root/test/node_modules/request/request.js:1163:10)
    at emitOne (events.js:115:13)
    at Request.emit (events.js:210:7)
    at IncomingMessage.<anonymous> (/root/test/node_modules/request/request.js:1085:12)

Answer 1

您的Utils.getCardsInSets返回undefined或null DATA 。 在上面的代码中，您没有将任何查询参数传递给该方法，请检查是否需要传递任何参数。

如果所做的一切正确，则方法将根据特定条件返回undefined/null 。 只需检查DATA然后确定其密钥长度即可。

Utils.getCardsInSets((ERR, DATA) => {
    if (!ERR) {
        allCards = DATA;
        var datalength = (!!DATA) ? Object.keys(DATA).length : 0;
        console.log("Card data loaded. [" + datalength  + "]");
    } else {
        console.log("An error occurred while getting cards: " + ERR);
    }
});