定义时不调用函数

Question

我很确定我将实例方法定义为函数，但在调用标有 <-- 的行时收到错误 TypeError: foundProduct.toggleOnSale is not a function 。我不明白为什么会这样。

const Product = mongoose.model('Product', productSchema)

productSchema.methods.toggleOnSale = function() {
    this.onSale = !this.onSale;
    return this.save();
}

const findProduct = async () => {
    const foundProduct = await Product.findOne({ name: 'Mountain Bike' });
    console.log(foundProduct)
    await foundProduct.toggleOnSale() <--
    console.log(foundProduct)
}

Answer 1

我认为您可能想在从中派生模型 class 之前尝试在模式上定义方法：

const productSchema = /* ... */;

productSchema.methods.toggleOnSale = function() {
    this.onSale = !this.onSale;
    return this.save();
}

const Product = mongoose.model('Product', productSchema)