Question

无法将未定义或空转换为对象错误

2017-10-29

2156

javascript node.js

此处的代码我最近无法启动，因为出现错误，无法将未定义或空值转换为对象：

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，您没有向该方法传递任何查询参数，请检查是否需要传递任何参数。

如果所做的一切都是正确的，则方法将根据特定条件返回 undefined/null 。只需检查 DATA ，然后获取其键长度即可。

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);
    }
});