将JSON查询字符串解析为JSON对象 [英] Parsing a JSON query string into a JSON object

问题描述

关于API的查询的结构如下:

The query on the API is structured like this:

../myapi/products?_q=genre,retail_price&_a=g,p&p.gt=10&p.lt=20&g.eq=POP

有两个数组:_q列出查询参数，_a列出相应的别名.所以p-> retail_price和g->类型

There are two arrays: _q which lists the query parameters and _a listing the corresponding aliases. So p -> retail_price and g -> genres

我可以将其解析为:

{$and : [ genre: { '$eq': 'POP' }, retail_price: { '$gt': '10' }, retail_price: { '$lt': '20' } ]}

快高兴了.但是这种方法存在两个问题: 1.'$ eq'等而不是$ eq等 2.数值现在是字符串'10'

Almost happy. But there are a couple of problems with this approach: 1. the '$eq' etc instead of $eq etc 2. the numeric value is now a string '10'

我认为(2)令人讨厌.由于服务器无法识别类型(也许应该是'10'而不是10).

I consider (2) to be a nasty one. Since the server cannot know the type (maybe it should be '10' instead of 10).

因此，我想尝试另一种方法.并将其全部解析为queryString，然后使用JSON.parse()进行转换

So, I want to try another approach. And that is parsing it all into a queryString and then convert that with JSON.parse()

首先，我放入一些查询字符串并在外壳中尝试它:

First I put up some query string and try it in the shell:

db.products.find({$and: [{genre: { $eq: 'ROC'}}, {retail_price: {$gt:7}}, {retail_price: {$lt:10}}]})

像魅力一样工作.

然后我尝试了此操作

var queryStr = "{$and: [{genre: { $eq: 'ROC'}}, {retail_price: {$gt:7}}, {retail_price: {$lt:10}}]}";

and :(产品是猫鼬模型)

and: (Product is a mongoose model)

Product.find(JSON.parse(queryStr), function(err, product) {
    if (err)
        res.send(err);

        res.json(product);
    });

令我惊讶的是，它根本没有用.

To my surprise it did not work at all.

也正在

console.log(JSON.stringify(JSON.parse(queryStr)));

不将输出写入控制台.

Does not write output to the console.

这是怎么回事?

推荐答案

第一件事是queryStr无效 JSON .您所拥有的是一个看起来像对象的字符串.但是您可能会问不是JSON吗?".简短的回答:不.长答案:由于JSON是一种轻量级的数据交换格式，因此它必须可由多种语言(而不仅仅是Javascript)读取.因此，引号是实现此目的的必要条件:

The first thing is queryStr is not valid JSON. What you have is a string that looks like an object. But you might ask "isn't that JSON?". Short answer: no. Long answer: since JSON is a lightweight data exchange format it has to be readable by a variety of languages (not just Javascript). So quoting keys is a requirement to make this possible:

var json = '{"foo": true, "bar": 123}';
var str = '{foo: true, bar: 123}';
console.log(JSON.parse(json)); // Object {foo: true, bar: 123}
console.log(JSON.parse(str)); // SyntaxError: Unexpected token f

因此，您可以 stringify 将查询对象转换为JSON，然后解析它，然后再将其传递给您的猫鼬方法:

So, you could stringify the query object to JSON and then parse it before passing it to your mongoose method:

// On the client
var queryJSON = JSON.stringify({$and: [{genre: { $eq: 'ROC'}}, {retail_price: {$gt:7}}, {retail_price: {$lt:10}}]});
// On the server
var query = JSON.parse(queryJSON); // Object

也就是说，回到您最初的两个问题:

That said, back to your original two concerns:

1. 引用的键名:它们在这方面的影响为零，因此它们根本不应该成为问题.
2. 不正确的值类型:看来您已经有一个将查询格式化为正确对象的过程，因此您可以使用 查看全文