javascript - 想要检查用户是否已经存在 MongoDB

Question

我的 promise 总是拒绝，即使我传入参数的_name并不总是与集合中的名称相同，任何帮助将不胜感激 谢谢!

    myCheckUser(_name) {
        var self = this;
        return new Promise((resolve, reject) => {
            self.db.collection("USER").find({ "username": _name }, { $exists: true }).toArray(function    (err, doc) //find if a value exists
            {
                console.log("DOC USERNAME: " + doc.username);
                if (doc) //if it does
                {
                    reject("Found user");
                    console.log(doc.username); // print out what it sends back
                }
                else // if it does not 
                {
                    console.log("Not in docs");
                    resolve("Not found continue logic!")
                }
            }
            )
        });
    };

Answer 1

如果找到数据，您必须解决 promise 并拒绝 promise 。我已更正您的代码如下:

    myCheckUser(_name) {
        var self = this;
        return new Promise((resolve, reject) => {
            self.db.collection("USER").find({ "username": _name }, { $exists: true }).toArray(function    (err, doc) //find if a value exists
            {
                if (doc && doc.length) //if it does
                {
                    console.log(doc); // print out what it sends back
                    resolve("Found user");
                }
                else // if it does not 
                {
                    console.log("Not in docs");
                    reject("Not found continue logic!")
                }
            }
            )