Can I determine if a string is a MongoDB ObjectID?

问题:

I am doing MongoDB lookups by converting a string to BSON. Is there a way for me to determine if the string I have is a valid ObjectID for Mongo before doing the conversion?

Here is the coffeescript for my current findByID function. It works great, but I'd like to lookup by a different attribute if I determine the string is not an ID.

db.collection "pages", (err, collection) ->
  collection.findOne
    _id: new BSON.ObjectID(id)
  , (err, item) ->
    if item
      res.send item
    else
      res.send 404

回答1:

I found that the mongoose ObjectId validator works to validate valid objectIds but I found a few cases where invalid ids were considered valid. (eg: any 12 characters long string)

var ObjectId = require('mongoose').Types.ObjectId;
ObjectId.isValid('microsoft123'); //true
ObjectId.isValid('timtomtamted'); //true
ObjectId.isValid('551137c2f9e1fac808a5f572'); //true

What has been working for me is casting a string to an objectId and then checking that the original string matches the string value of the objectId.

new ObjectId('timtamtomted'); //616273656e6365576f726b73
new ObjectId('537eed02ed345b2e039652d2') //537eed02ed345b2e039652d2

This work because valid ids do not change when casted to an ObjectId but a string that gets a false valid will change when casted to an objectId.

回答2:

You can use a regular expression to test for that:

CoffeeScript

if id.match /^[0-9a-fA-F]{24}$/
    # it's an ObjectID
else
    # nope

JavaScript

if (id.match(/^[0-9a-fA-F]{24}$/)) {
    // it's an ObjectID    
} else {
    // nope    
}

回答3:

I have used the native node mongodb driver to do this in the past. The isValid method checks that the value is a valid BSON ObjectId. See the documentation here.

var ObjectID = require('mongodb').ObjectID;
console.log( ObjectID.isValid(12345) );

回答4:

Here is some code I have written based on @andy-macleod's answer.

It can take either an int or string or ObjectId and returns a valid ObjectId if the passed value is valid or null if it is invalid:

var ObjectId= require('mongoose').Types.ObjectId;

function toObjectId(id) {

    var stringId = id.toString().toLowerCase();

    if (!ObjectId.isValid(stringId)) {
        return null;
    }

    var result = new ObjectId(stringId);
    if (result.toString() != stringId) {
        return null;
    }

    return result;
}

回答5:

If you have the hex string you can use this:

ObjectId.isValid(ObjectId.createFromHexString(hexId));

回答6:

It took me a while to get a valid solution as the one proposed by @Andy Macleod of comparing objectId value with its own string was crashing the Express.js server on:

var view_task_id_temp=new mongodb.ObjectID("invalid_id_string"); //this crashed

I just used a simple try catch to solve this.

var mongodb = require('mongodb');
var id_error=false;
try{
    var x=new mongodb.ObjectID("57d9a8b310b45a383a74df93");
    console.log("x="+JSON.stringify(x));
}catch(err){
    console.log("error="+err);
    id_error=true;
}

if(id_error==false){
   // Do stuff here
}

回答7:

For mongoose , Use isValid() function to check if objectId is valid or not

Example :

var ObjectId = mongoose.Types.ObjectId;
if(ObjectId.isValid(req.params.documentId)){
   console.log('Object id is valid'); 
}else{
   console.log('Invalid Object id');
}

回答8:

The only way i found is to create a new ObjectId with the value i want to check, if the input is equal to the output, the id is valid :

function validate(id) {
    var valid = false;
    try
    {
        if(id == new mongoose.Types.ObjectId(""+id))
           valid = true;

    }
    catch(e)
    {
       valid = false;
    }
    return valid;
}

> validate(null)
false
> validate(20)
false
> validate("abcdef")
false
> validate("5ad72b594c897c7c38b2bf71")
true

回答9:

mongoose.Types.ObjectId.isValid(string) always returns True if string contains 12 letters

let firstUserID = '5b360fdea392d731829ded18';
let secondUserID = 'aaaaaaaaaaaa';

console.log(mongoose.Types.ObjectId.isValid(firstUserID)); // true
console.log(mongoose.Types.ObjectId.isValid(secondUserID)); // true

let checkForValidMongoDbID = new RegExp("^[0-9a-fA-F]{24}$");
console.log(checkForValidMongoDbID.test(firstUserID)); // true
console.log(checkForValidMongoDbID.test(secondUserID)); // false

回答10:

Warning: isValid will return true for arbitrary 12/24 length strings beginning with a valid hex digit. Currently I think this is a better check:

((thing.length === 24 || thing.length === 12) && isNaN(parseInt(thing,16)) !== true)