Javascript 如何检查查询字符串是否在 Express.js/Node.js 中有值？
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How do I check if query string has values in Express.js/Node.js?
提问by blundin
How do I check if a query string passed to an Express.js application contains any values? If I have an API URL that could be either: http://example.com/api/objectsor http://example.com/api/objects?name=itemName, what conditional statements work to determine which I am dealing with?
如何检查传递给 Express.js 应用程序的查询字符串是否包含任何值？如果我的 API URL 可能是:http://example.com/api/objects或http://example.com/api/objects?name=itemName，那么哪些条件语句可以确定我正在处理哪个条件？
My current code is below, and it always evaluates to the 'should have no string' option.
我当前的代码在下面，它总是评估为“应该没有字符串”选项。
if (req.query !== {}) {
console.log('should have no query string');
}
else {
console.log('should have query string');
}
回答by Ravi
All you need to do is check the length of keys in your Object, like this,
你需要做的就是检查你的密钥的长度Object，就像这样，
Object.keys(req.query).length === 0
Sidenote: You are implying the if-else in wrong way,
旁注：您以错误的方式暗示 if-else，
if (req.query !== {}) // this will run when your req.query is 'NOT EMPTY', i.e it has some query string.
回答by Pranav Shekhar Jha
If you want to check if there is no query string, you can do a regex search,
如果要检查是否没有查询字符串，可以进行正则表达式搜索，
if (!/\?.+/.test(req.url) {
console.log('should have no query string');
}
else {
console.log('should have query string');
}
If you are looking for a single param try this
如果你正在寻找一个单一的参数试试这个
if (!req.query.name) {
console.log('should have no query string');
}
else {
console.log('should have query string');
}
回答by Nikhil Vats
回答by pcodex
I usually check if the variable in the query string is defined. Using the url package in ExpressJS it would be so:
我通常检查查询字符串中的变量是否已定义。在 ExpressJS 中使用 url 包会是这样：
var aquery = require('url').parse(req.url,true).query;
if(aquery.variable1 != undefined){
...
....
var capturedvariablevalue = aquery.variable1;
....
....
}
else{
//logic for variable not defined
...
...
//
}
