Mongodb:findById() 不返回任何值

Question

即使数据库中存在 id，以下 findById() 也会返回 null:

router.get('/product/:id', function (req, res) {

console.log("product id = " + req.params.id);

//produces product id = 596161e1734d1d25634366ce

var id = req.params.id;

Product.findById({_id: req.params.id})
    .exec(function (err, product) {
        if (err) {
            console.error('Error retrieving all product by id!');
        } else {
            console.log('server product = ' + JSON.stringify(product));
            res.json(product);
        }
    })
})

数据库中的目标文档:

{
    "_id": {
        "$oid": "596161e1734d1d25634366ce"
    },
    "producttype": "stove",
    "name": "30 in. 4.8 cu. ft. Electric Range in Stainless Steel",
    "brand": "Amana",
    "model": "AER6303MFS",
}

型号:

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const ProductSchema = new Schema({
    _id: String,
    productType: String,
    name: String,
    brand: String,
    model: String,
    price: Number,
    discount: Number,
    description: String,
    rating: Number,
    sku: String,
    warranty: String,
});

var Product = mongoose.model('Product', ProductSchema, 'product');
module.exports=Product;                  

Answer 1

尝试从您的 ProductSchema 中删除 _id。 id 将由 mongodb 自动生成。之后尝试使用

Product.find({_id: req.params.id})
    .exec(function (err, product) {
        if (err) {
            console.error('Error retrieving all product by id!');
        } else {
            console.log('server product = ' + JSON.stringify(product));
            res.json(product);
        }
    })
})

或者如果你想使用通过 id 查找然后使用

Product.findById(req.params.id)
    .exec(function (err, product) {
        if (err) {
            console.error('Error retrieving all product by id!');
        } else {
            console.log('server product = ' + JSON.stringify(product));
            res.json(product);
        }
    })
})