为什么MongooseJS不推送到数组？

Question

这是原理图

const DollSchema = new mongoose.Schema({
        firstName: {type:String, trim:true},
        lastName: {type:String, trim:true},
        stabCount: {type:Number},
        isActive: {type:Boolean},
        curses: [{type: String}]
    });

const Doll = mongoose.model('doll', DollSchema);

这里是应该将其推入阵列的代码

Doll.findOne({firstName:req.body.firstName, lastName:req.body.lastName})
    .then(dolls => dolls.curses.push(req.body.curse))
    .catch(err => console.log(err));