从查询字符串参数推断正确的数据类型

Question

I'd like to infer the types from parameters of a query string (using Javascript).

Example URL:

http://example.com/some/path/here/?someString=Hey&someNumber=20

I've used a couple of packages ( query-string and simple-query-string ) like so:

queryString.parse(request.url)

Where request.url is the url above. This gives the following:

{
    "someString":"Hey",
    "someNumber":"20"
}

Where someNumber above is type string . The desired result is:

{
    "someString":"Hey",
    "someNumber":20
}

Where someNumber is type integer .

The reason I want integer type is because I am performing JSONSchema validation on the parameters which specify the types which are allowed per named parameter.

I am aware that I can cast these instances, but I'd prefer if it was available from a package since it feels a lot like reinventing the wheel.

Answer 1

This should do the trick. You could potentially add more/different regex tests to supplement the simple number check that's in place now (for instance, detect dates, dollar amounts, telephone numbers etc.)

 var exampleurl = "http://example.com/some/path/here/?someString=Hey&someNumber=20" function getQueryStringData(url){ var data = url.split('?')[1].split('&'), numberRgx = /^\\d+(\\.\\d+)?$/ return data.reduce(function(obj, t){ var pair = t.split('='), key = pair[0], val = pair[1] obj[key] = numberRgx.test(val) ? parseFloat(val) : val return obj }, {}) } var obj = getQueryStringData(exampleurl) console.log(obj) document.getElementById('output').textContent = JSON.stringify(obj) 

 <div id="output"></div> 

Answer 2

Here is one method of typecasting an object's properties. if the string itself is one of the special matches in the expression, JSON.parse it, else try Number, else leave it as-is.

  function cast (o) {
    var result = {};
    for(var prop in o) { if(o.hasOwnProperty(prop)) {
      var val = o[prop];
      if (typeof val === 'object') return o[prop] = cast(val);
      result[prop] = /^(true|false|null|undefined)$/.test(val) ? JSON.parse(val) : Number(val) || val;
    }}
    return result;
  }

cast( { a: '123', b: 'null', c: 'abc' } ) returns {a: 123, b: null, c: "abc"}